KTM Cheese Cams Issue

[@Adv_Charlie]

Absolute legend! I knew you were the right person to give my head to and find the issue. Sorry you can’t go any further but £2,500 ish is a lot of money that I’d like back. I hope KTM pay everybody back that had to pay out for this issue. Why they thought they could hide it when we have the power of the internet and clever people like Matt around i don’t know. Thanks again.

[@fuzzy1dk]

Toyota/Lexus just recalled 100k cars to have the engine replaced because it eats one of the main bearings, so they would be in good company

[@56Model30]

Excellent detective work and good explanation

[@gafrers]

Thanks for sending it to Matt for this.

[@gordo5863]

Made In Austria?

[@To_who_knows_where]

That'll be a big chunk of money to get back for your travels Charlie.

[@Brad-RB]

It all depends on how deep the jets screw in. It may be more of an issue with inconsistent counterbore depths. I'm a mechanical designer, and cross-drilling manifolds with offset centerlines is a common practice. The intersection produces an elliptical feature. As long as the jet does not thread in so far that it blocks the "ellipse", it should be fine.

[@mcqcjc8409]

. I'm a mechanical designer, and cross-drilling manifolds with offset centerlines is a common practice. I am not an engineer but i would like to ask why would u want to cross-drill with offset? Sounds seriously stupid.

[@Brad-RB]

@@mcqcjc8409 , usually, it's because there is not enough room. That is the case on the KTM head. If they lined up the holes, the oil jet would not have directed the oil to the center of the cam lobe/follower. If you want a compact and light engine, this is the trade-off.

[@MotoDuoMedia]

Exactly what I was thinking.

[@mcqcjc8409]

@@Brad-RB So its not lack of the room - its a design fault.

[@Brad-RB]

@@mcqcjc8409 It might be, but it's more likely inconsistencies in the machining process. There are a lot of variables in play.

[@emefff]

When I applied for a job at the KTM factory a few years ago they asked me: "Are you a moto rider?" "Sure" "Which make do you ride" "Yamaha" (the then new MT-07) The conversation went on and the head honcho of quality told me: "We know the Japanese do their high load engine approval runs for 1000 hours. But we think 100h is enough." Any more questions??

[@emefff]

I want to add that this guy also, with sincerety, talked about glueing instead of welding the truss frames. I don't want to say it's impossible, but it's a bit far from reality as basically everybody knows: there are no glues for parts with 100°C (the frames get a bit hot). Except this guy 😂

[@Omar411269]

This hypothesis is all dependent on how deep the jet screws in. If it doesn't occlude the intersection then it should work fine. Fluid doesnt really care about hole alignment. Under pressure, as long as the boundary layer at the edge of the flow isnt too turbulent then all you need to worry about is pressure. And oil is specifically design to be less turbulent. Source: Biomedical Engineer who did a lot of fluid mechanics projects

[@sadeqalbana]

I'm not a mechanic or a scientist but the oil used in these engines is relatively thick, not sure if it makes any difference

[@Omar411269]

@@sadeqalbana Not really. Hot motor oil is only about 2-3x as viscous as blood and the smallest oil passages in a motor are as big as the largest arteries.

[@lauraiss1027]

You are correct about jet depth still, if we take in account the given facts that cams are chewed and they are hard enough, then only other possible issue is not enough oiling. That's it, there is nothing more, it's whether oiling or cheese cams. One might even argue that the fact cams are chewed still being hard enough for the purpose is enough evidence that the jets are screwed as far as to block the passage. Only other possibility is that there is not enough oil pressure in head unit to begin with which I doubt, since it's only some of cam lobes chewed down to that ridiculous level and other components like journals and such seems fine (based on pictures from other sources), meaning the issue is in particular oil paths. So at the end of the day, while you are correct, issue stated in this video is the logical reason behind failed product.

[@Omar411269]

@@lauraiss1027 I disagree. Valve train design is pretty complex. It can be anything from bad alloy used in manufacture or bad cam chain tension, to intricate stuff like bad design of striking angle for the cam lobes. In fact I would gamble that the oiling is absolutely fine. Why? There should be obvious overheating signs like bluing where-ever there is oil starvation and I havent seen any examples of that. My best guess is the cam is either made of bad alloy or it was not properly treated for sufficient hardness. That's about as much as I know about materials tho.

[@scotttaggart]

Well, it's a theory but maybe not a good one. First, as others have mentioned, if the jet doesn't bottom out, then the first part of your theory is 100% wrong - the jet would not be cutting off part of the flow. For the moment, let's assume the jet is not bottoming out... Now, you might keep arguing that the cross-drilled holes don't line up so the flow is restricted there. Nope, it ONLY matters if the flow in the reduced cross drill hole is less than the jet's designed flow which it probably is not since the jet opening is VERY small. The JET is the smaller of the holes so it matters little if some of the cross-drilled surface area is not entirely open - it only matters that the cross-drilled area is somewhat larger than the jet opening (which it most likely always is). Let's say the jet is 1mm^2 and the cross drilled are is 2mm^2 (but in theory, under ideal drilled situations should be 5mm^2). Using these numbers we see the 2mm^2 hole will have little or no effect on the flow because the "gate" is the jet at 1mm^2. You theory on the oil "backing up and squirting out on the journals" would ONLY apply if the cross-drilled holes were, for the most part, smaller than the jet hole sizes. I will admit that I don't know the smallest cross drilled sizes in the real world (and you probably don't either) (since, as you say, they differ from head to head) but unless you can show in some definitive way the holes are substantially blocked by the drilling being offset or the jets themselves are bottoming, your theory is largely unsubstantiated and unproven (and unprovable). Assuming for the moment that the jets are bottoming (which I do not concede), a simple fix would seem to be to shorten the jets slightly on the threaded end and/or drill a bigger hole in the bottom of them to increase the opening size where it meets the bottom of the threaded hole.

[@christoforostalaklis3185]

There is an easy way to confirm your hypothesis without cutting it . Screw the jet, put a light into the feeding hole and it would be very easy to confirm the actual size of the oil passage between the oil jet hole and the cross drilling hole

[@mattseaman5397]

I hope Charlie gets his money back. Actually he should get even more for all the shenanigans.

[@Adv_Charlie]

That might be wishful thinking. If there is a chance i’ll take it.

[@TwoWheeledPotato]

@@Adv_Charlie Always worth getting your money back if possible. it's a shame you've ended up with a lemon

[@markmenzies4218]

I have to agree, the KTM 'fix' putting a filter in the head is just plain stupidity. what are they thinking the oil filter is breaking up? then the head filter clogs & destroys the whole head?

[@PotatoeJoe69]

It will slow down the cam wear and keep bearings safe 🤪 It's stupid. It's not fixing anything, it is just making a smaller repair bill. They need to make cams with better metals, make the oil passages to the cams bigger, and put an oil pump that moves more volume with more pressure.

[@ItsJustJussi]

They might have had heads with a clogged jets, meaning that shavings (or something) got into the cam follower jets and clogged one or more and caused a cam failure. They might have honestly thought this was the main issue. Hard to say. With the filter not resolving anything definaltely more work and investigation should have gone into how the jets are fed. Problem is, that if they pulled 50 heads off a production line and tested them, the might have all passed. I am not defencing KTM by any means. They did a horrible job with this issue. Seeing how this was done it looks like a design issue that doesn't take tolerancing very well. There shouldn't be a oil feed failure if machining is off withtin tolerances from just the design basis already.

[@sharg0]

As a CNC-technician I don't think it's the offset that's wrong, more likely that the counter bore is made to deep and/or the thread on the nozzles to long. But just my 2 cents. I sure hope that the guy gets his money back and that KTM dives into the issue if this isn't a one-off.

[@latemnf]

I was wondering if it could be a combination between using too long of a drill bit to clear their fixturing or something then not changing the tool out often enough and getting a good amount of drift while doing the Z axis drilling operation.

[@A.Doll.Fiddler]

@@sharg0 My thoughts exactly, if the jet was shorter/chamfered in the inner diameter/positioned further outboard, the threads wouldn't be blocking where both bores intersect. The misalignment isn't ideal but could've been mitigated with a simple tweak

[@sharg0]

@@latemnf Most unlikely. Carbide drills are almost the only thing used in production these days and they are very stiff so they break well before they show any noticeable amount of drift. So while no hole is perfectly round nor straight the deviation is within µm.

[@rkatz1000]

A misalignment of this magnitude in today’s machine world is unacceptable.

[@mastergivenn]

I am tempted buying a 790 Adventure 2024…this analisys doesn’t encourage me…The tesd ride I have done, showed me a noisy engine..I wonder if a 2024 790 twin is fully reliable or not.

[@ShaneVerhoogt]

Machinist here. Great break down and synopsis of the issues, however KTM has a bigger issue with that head, oil passage ways and squirter nipples. Conventionally speaking probably due to cost and production limits the machining process was incorrect. So with a Conventional drill bit long shank [which was probably used due to the bevelled upside down triangle in the bottom of the passage way] this causes a vortices as the oil get pressurised highest at the bottom then has to come back up the the spray jet/nipple and due to being offset and swirl it can't be sprayed out at regular pressure... If KTM had reamers, which I'm sure they do [but cost and absolute fortune] a flat bottom passage way would pressurise better without vortices. Even if it sprayer/nipples weren't offset it still wouldn't be right.... Great video though 👌 Thanks brother 🙏

[@cliftonsr]

Showing signs of lack of oil lubrication due to the darkened and charred look on those badly worn lobes, and Matt I believe you are on to it with your brilliant analysis.

[@GazBromley]

Never buy KTM.I test rode the 1290 duke, brilliant bike...i then spoke to other duke owners at pubs etc and they all said they cost big to repair. On top of that, i put on the KTM superduke page that i was interested in buying one. I had dozens of messages of guys trying to sell. mmmmm. Alarm bells. I decided to buy an MT-10, guess how many guys messaged me trying to sell when i put the same post on the MT-10 page....NONE. No one wanted to get rid. I bought an MT-10. 2 years of ownership and it still blows my mind. Ive spent money on tyres, MOTs and services. It toured the scottish highlands, i made panier brackets. 1033 miles in 4 days. I red lined it so much, Loch Ness To Skye 100 mph bends. Ive abused my 2016 MT-10 to hell, and used it daily to work, what a bike. Still sounds like new.

[@Jonathan-L]

MT10 is one machine that I lust for. They're rare in my part of the world, and that's another reason why they're so cool.

[@fs5866]

My Africa Twin 2020 will do close to 1000 miles in under 24 hours, so try to beat that, departing is tomorrow, destination is Uk to Italy.The stallion has 60k miles on the clock and just had a brand new clutch plates and springs put in, gonna be redlined at every opportunity on the way.

[@sonny9608]

So you’ve never owned a Ktm yet bash them incessantly… moron

[@hipposnakeyo]

Yep. I could pick up a 1290 for less than my mt10 sp but I still went for the Yamaha. Marginal performance gain is nothing for a road bike when compares to trouble free ownership experience

[@Delerium82]

Thanks Matt, I own one of these bikes and have been eager to see your analysis. KTM should give you a check for figuring out their quality control problems.

[@bigding4507]

They know what the problem is but are keeping their heads in the sand

[@mavbike]

Excellent video. As a machinist, it gives me several ideas of how to help longevity if I do one of these for a customer. This is the kind of stuff I look for when doing a engine.

[@Shahar_C]

TBH, it doesn't look like the root cause to me. The jets will have to block the flow path in order to be the cause, and they are just not that deep in the drilled hole.

[@villiamo3861]

Why? Partial blocking might well be enough ( *if* that's what you're arguing against), and the guy sounds entirely plausible in saying there's enough misalignment for such partial blocking. Although a smaller (but still somewhat open) effective jet would give a load of pressure (when converted back from speed on the far end of the jet), if there's not enough volume being supplied as well (and the 'final' pressure will never go up enough to compensate entirely for the lack of volume) then there's a concomitant lessening of designed/expected flow, and there's a problem. Were it otherwise, Mikuni, Keihin et al might as well have supplied the same size main jets (and indeed airbores) for all carbs used in all engines of differing power, as they'd always be passing it all through; and we could still be flying in tourbojetted rather than turbofanned airliners (whose engines also partly deal with the same question of overall flow). Though we do want a pressure difference, sizable jet/bore etc cross-section is surely required to be 'sufficient' as it counts to the necessary & required *volume* of 'new' oil delivered every second.

[@Shahar_C]

@villiamo3861 Because he looks at it from a top view from a 2D perspective. When you look at the cross section of the intersected area between 2 drills in 3D perspective, you'll see that there is no blockage issue, and this is more than enough diameter for good flow.

[@SkinPeeleR]

​@@Shahar_CSo, what caused it then?

[@richardjones3112]

It was always going to be an oil supply problem with that amount of lobe wear.

[@villiamo3861]

@@Shahar_C Nice answer and I get what you are saying. But I still think just the '2D misalignment' enough to cause a problem with the flow. The system, perhaps designed by KTM to flow just enough, say, but put out of alignment in production, will (in my opinion) provide ensuing pressure differences reflecting through the flow-bore such that the potential/expected flow is not achieved, and the real flow of material/oil is through a narrower internal channel of fluid in that flow-bore than the cams etc were designed for - ie with the other, hindered, oil becoming relatively static, changing its speed for pressure (worse, perhaps causing eddies) - in the way a relatively sharp turn in a valve intake port of a (normally arranged) combustion engine has the gas-fluid refusing to turn/flow around, for example, the outer corner pocket of the turn at the same time as the rest of the gas flow: it cannot do that much work - and the 'barrier' can be almost defined as being anything other than a gentle curve: though only partial and, in a way, at a distance from the source pressure, it backs up some of the (in this example) outer flow to some degree, so reducing the supplied volume of that fluid. And is what is actually supplied then enough for your demands?

[@jozefsk7456]

Hi Matt, thx to your channel I will be able to repair an old scooter. You mentioned the method of finding old OEM part numbers first on the manufacturers website, then ordering them through ebay - its a life saver, also skimming the service manual first helps. Cheers.

[@B5anto5]

KTM790 Adventure 2019 owner here, ~52000 KMs under the belt, last trip to the Pyrenees did around 3000KMs in 5 days, no issues, love the bike.

[@eqaulo]

Thanks for this Matt, well explained! I have a '19 790 AdvR, with about 20k km's on the clock and has been running fine so far. Will have mine checked during winter time, fingers crossed.

[@robsnodgrass915]

Worked last year at a KTM stealer ship. They come in like crap, I was surprised. They require twice the work to assemble, cost more than everything else, and warranty work piles up. Looks like the marketing is working better than the reality of the product.

[@motozz8258]

Has done for two decades , the marketing of a polished turd is the title of that reality , our local stealership had to expand workshop area and employees to meet the needs of Warranty and the out of warranty KTM offroad bikes . That was back when they had Blue ktms , the HusabergKtm. They are like Presidents you dont ever get to know the truth, but it is finally being seen .

[@billyarsenault1970]

Jeez I really feel for anyone saves up to pay top dollar for a flashy new bike and then it blows up in a month or so. Riding Red might not be Ready to Race but at least you will be riding instead of crying

[@motozz8258]

@@billyarsenault1970 The fake redktm white one and orange are so far from ready to race it is laughable . First up the Suspension needs to Fixed out of the box , all the reliability issues from brand new the factory teams swap out the dodgy bits , fuel filters that crack and drop pressure , fuel pumps that fail and near kill you on a double , 5 hr bike . Ride Real Red for sure

[@hunterssports]

As a experienced former mechanical engineer. What you are pointing out is a restricted port of flow. Given Pascal's law: (Blaise Pascal, 1623-1662). Every force acting on a stationary fluid generates a pressure that propagates in all directions with the same magnitude. As you have stated the flow rate possibly may be compromised even if the pressure is consistent.

[@AceCarleton]

I do think that a lot of the problem is the oil Drain interval and the oil experiencing high temperature shear and losing viscosity. Guys were testing their oil at 5000km and it was testing as a 10w30 viscosity. As viscosity breakdown occurs oil pressure drops off. No pressure = poor squirting. The motorex oil has the worst high temperature Shear value i have seen reported. Simply switching to an oil with better high temperature shear and changing it more often may save the Cams.

[@hunterssports]

@@AceCarleton Generally I do change out my toys oil with full synthetic and filter at or before 5000km. Oil dilution is a big factor. Gas blow by past piston rings. Burning scorching of lube, foreign contamination like condensation. Also the KTM issues that I've looked over, are in my personal opinion is a lack of sufficient lubrication. eg some talk about soft metal used in manufacturing of the camshaft.. If so, the cam may warp, twist and may experience loss of rotational alignment. Their has been no evidence of that characteristic. So lubrication issues are what I feel is the cause of this epic failure. Remember the purpose of good oil lubrication is to keep the metal surfaces from comming into contact with each other

[@sadeqalbana]

@@AceCarleton I can confirm that, I've used motorex once and I'll never use it again, I live in very hot climates and motorex just don't hold well

[@Jipeskripes]

​@@AceCarletonis Motul 15w50 5000 ok for ktm?

[@iceclimb1897]

MATT .... The miss alignment is creating a non-engineered limiting valve. What it needs is a flow test between good and bad lobes. These valves are used in big, outside, Hot Water systems. They protect the system from over pressure, from Mains Pressure, which varies on how far you are from a pump. They are a simple small hole through a plate. No matter the pressure before it will be the listed pressure. When it's water to water its a limiting valve. When it's water to air it's a spray nozzle or jet. I think there is a pressure drop and the effected cam lobes are not getting the engineer designed correct lubrication. Also the turbulence in there if the jet is lower pressure. Got down to a hardware store, plumbing section, and and look at simple limiting valves not the more complex hammer protection combination. put that great mind of yours to work. Love your work. Been following you since your Yam T-Shirt days with the white board in you old place ..... Good luck mate :)

[@cliftonsr]

I would like to see the oil squirting out through the jets at idle and all different rpm ranges to really solidify your finding on this. Brilliant work on these findings and this could be the best analysis to date on the 790/890 KTM camshaft problems. And your videos are why I subscribed and become a member of your channel Matt.

[@AllAverageAdventures]

There have been videos of people with worn cams showing the oil squirters working fine with the engine running off the starter alone. So I don't entirely agree with these findings.

[@A.Doll.Fiddler]

Makes sense but devils advocate here, maybe I'm misunderstanding: If the thickness of the threaded shoulder on the jet was 2mm and you're saying that is reducing the already reduced intersection at the cross drilling then surely the jets would have to be butted up fairly close to the intersection. By eye, Im thinking the jet would have to thread in maybe ~20mm deep which sounds unreasonably long doesn't it? Also if this is the cause then surely the easiest fix is to either chop the jet shorter or chamfer the inner diameter on the threaded section of the jet

[@dirtygarageguy]

20mm... no, the threaded hole is not 20mm deep. The feed hole is intersecting just the corner of the hole, not bisecting it. The two nozzles are both feed by the same feed and they do not connect to each other.

[@jacktupp1427]

Sorry, I'm not convinced that is the issue, "alignment". Of both drillings. You have not given any measurement or depth of said jet, when seated. The jet cavity clearly goes down and past the depth (width) of the vertical drilling. Clear space for fluid travel. So unless the jet nozzel goes down past the vertical drilling and then bottoms out, restricking the flow ( in to or out of the vertical drilling) you have a mute point. As a fluid under pressure will flow, even if drillings are offset, providing there is a space. Further, a top & bottom view of said jet would be useful to understand how it functions as a whole. You stated the flow is down the vertical drilling. So then how is the jet feed? If on your further statement, "the jet uses fluid dynamics to increase pressure, through it's nozzle"? This would then be flow in the opposite direction and up the vertical drilling or did I miss something? Also, you have not given us a look at all of the remaining drillings (offset or not) for comparison. Is that four per cylinder?

[@justmyself1000]

@@jacktupp1427 The vertical and horizontal are not lining up....because they are not lining up...the horizontal (where oil jet is screwed in) is partially occluded. Because of the occlusion....the proper volume and pressure is not coming out of the jet, especially under higher RPMs.

[@C_R_O_M________]

@@justmyself1000 building oil pressure should push oil through the jet, offset or not. Now if that nozzle is narrower or wider than it should that's a different issue. I honestly don't know.

[@justmyself1000]

@@C_R_O_M________ It's not just a matter of pressure, but oil volume.....But if the passageway is partially occluded, it will not only affect the volume, but the pressure.

[@leonplummer-g1f]

Simple exercise screw in a jet put oil in a syringe see what comes out and how much pressure is needed to get it through

[@hardyeleonore]

Ok so why cant they shorten the thread on the jet protruding into the oiler hole or taper the back side of the oil jet to get a little more volume where its cross drilled for a fix.

[@Bristolcentaurus]

the problem is the misalignment of the 2 holes there is not enough area because one hole is offset relative to the other to put sufficient oil through to create a big enough squirt to get sufficient oil to the lobe

[@Thebowber]

@@Bristolcentaurus This miss alignment is only a problem if the bottom of the jet covers the area of the cross drilling, if the jet isn't long enough to reach the cross drilling then you just have a cavity feeding the jet and alignment doesn't matter. If the oil feed problem is to do with this miss alignment then a shorter threaded section would help, even adding a countersink to the back of the jet would help.

[@hardyeleonore]

@@Thebowber Thats what I was thinking.

[@Bristolcentaurus]

@@Thebowber how much cross sectional area do you have ? how much oil can that cross sectional area flow ? any reduction in cross sectional area is a restriction to flow and a restriction to flow is a restriction to flow

[@RT-tn4ry]

EXACTLY !!

[@mateuszkasza]

If nozzle plugs the oil passage with the thickness of the thread area simply adding a countersing to back of the nozzle I think would do the work.

[@rkatz1000]

As someone mentioned already, a tapered inlet on the rear of the the jet maybe all that’s needed to prevent flow restriction

[@gercole1651]

Enjoyed watching that. Not got a clue about the inside of engines, nice to see what goes on inside them.

[@byrnestuff]

It’s not so easy to visualise the issue, I sort of can, but if the jet screws too far in, and that causes oil flow to be blocked, that implies either the jet or head could be at fault. I guess the main point is that if your engine has this issue the cams will be damaged and parts will need to be replaced. There is no point fixing the issue by modifying parts as the damage will already have happened. Another issue is that metal particles will have circulated around the engine, and although the filter should capture these there is still the possibility of bearing damage elsewhere. Obviously if you had the jets and knew which jet went in each hole you do a flow test to get a 100% diagnosis.

[@billboilermaker8733]

if this is the problem, I cross drilled holes not quite lining up and the thick edge of the oil nozzle obscuring full oil flow surely a simple solution would be to use some sort of countersinking tool and flare the back end of the nozzle

[@cbuzz2371]

This explains why a new head was fitted to Charlie's bike, KTM know where the fault lies.

[@richardjones3112]

100%.

[@SuperbikeSurgeryTV]

I think as others have already alluded to, this theory only stands up if the threaded section of the jet is too long in relation to the depth of the hole it's screwing into (bottoming out). it's a shame the original jets weren't included with the head. The theory works well when drawn in two dimensions, but when modelled in three, there's likely enough of a pass through for the oil so as not to cause any restriction in flow 🤔

[@ondrejskorunka9333]

But if there is a cavity behind the nozzle there is no restriction to the oil flow. For the flow to be restricted the thread of the nozzle must be blocking the vertical channel... Simply put if the crossdrilling for nozzle is longer (more meat for the drilling needed) so that the thread of the nozzle do not restrict the vertical hole by its thread it must work correctly even drilled by this manner. Am I right or got it all wrong?

[@prydzinski]

you are right, but if the holes are misaligned significantly the crossection area where both holes meet are the limiting factor.

[@g.w.3816]

Watched this just out of curiosity too see what going on with ktms, very informative and easy to understand 👍

[@albundy6057]

What would happen if the oil pump isn't creating enough pressure at low revs?

[@mihaicrenganis2943]

If the oil is good, the camshafts are well treated, and the valve/camshaft tolerances are within specifications, no problems will arise for sure. There are videos on KZbin where you can see that the alignment of the lubrication channels is not the issue. The pressurized oil circulates absolutely everywhere, regardless of alignment! Very important is checking the camshaft/valve clearance/tolerance.

[@ktm525gp]

Alighnment or not. It still gets oil thru it. Alignment could be an issue with flow. It can be fixxed and redrilled and modified. Also. Proper alignment on the jets aiming at the area between cam and follower. I also feel it maybe loosing oil psi do to now seal between cam cover and head. Yes its machined but can still leak thru. Personally id love to get my hands on a head and modify it for bearings on the cam. And redoing the oil feed. Id reassemble it and hook a pump to it and run it on a bench in a oil bath. Id be curious on the cross drill if it can be ported to align the flow. Great video. Another thing i believe there could be a binding issue with follower to valve. If rockers is under lobe and pushing on valve but not sliding across it.

[@ktm525gp]

Also lack of valve adjustments can cause the where to cam faster do to lack of valve clearance. So oil cant lubricate properly. Like mechanical flat tappet camshafts. Wonder if running a bigger gap would help. Or if valves are stretching to much.

[@MarkOneMoto]

Great video Matt, KTM should give you a consultancy payout for that 😀..very well explained 👏🏼

[@karachaffee3343]

You could use close fitting pin gages in the bores and measure the distances to the edge of the casting to get an idea of the centers of the bores.

[@williamdillon7708]

Go back two weeks to "Dirty Garage Guy" Cheese Cams. He explains in detail the problem isn't the density of the cams but the failing oiling system. He spells it out so thoroughly, I think he should be called as an expert witness: )

[@claran9393]

Brilliant analysis. It’s absolute shambles from KTM to make people pay and claim it’s “user error” or lack of servicing. Clear as day that it’s a manufacturer default well done for proving it

[@gefragop]

Great finding. Thiw could be solved by boring the vertical holes to a larger diameter.

[@clivelockwood3236]

I'm not sure if that would be the problem, only if the threads bottom out.

[@rafaellastracom6411]

I thought the same thing initially BUT I believe he has hit the nail on the head actually. You would be correct IF the threads extended all the way down to the other drilling which looks to be anywhere from 40-50mm deep. That is not the case. Why would you drill a threaded hole 40mm when all you need is 10mm max for thread engagement? You wouldn´t. As such, the only hole that reaches the other cross-drilling is the actual smaller diameter. In the end the contact area is defined by the overlap of both smaller diameter holes and they need to be very, very accurate. If they are not dead on the orifice will be starved by insufficient feed pressure and then say goodbye to your cam. I think he´s got it.

[@64faffi]

Reminds me of the first generation Viragos/XVs, where the banjo bolt for the oil lines going to the cylinder heads had not been drilled fully through. There was a tiny hole, but not the intended 4 mm. Result was the same; cams (and rocker arms) destroyed.

[@jaromor8808]

I'm Czech and I was told KTM stands for "Každej Tejden Motor" ~ "Engine Every Week"

[@mariohabinger378]

In Austria there is a saying KTM stands for "Keine Tausend Meter" (no 1000 meters (between repairs)) 😜 but i still love my ktm!

[@warwickscram1656]

In England 'Keeps taking money'.

[@mariohabinger378]

@@warwickscram1656 🤣

[@peterbonivart6818]

In Sweden it's "Knuffa Till Mål" - push to the finish line.

[@mariohabinger378]

​@@peterbonivart6818 Nice to see that KTM is internationally known for its reliability 🤣 Still love the bikes.

[@timwhiskerd2133]

It all depends on the thread length of the jet. If it covers the vertical drilling then there is a problem but if its short then there should be no issue. Validate be making flow checks.

[@Jonathan-L]

Not only do casts on legs help when you jump out of a car at the point arriving at the workplace, but you can paint them to make them look like Fox/Gaerne/Sidi/Alpinestars etc!

[@maxpool162]

I wonder why they made it more complicated to machine comparing to big twins, where oil jets are installed directly on the cam bridge and these motors have zero issues with cams and have even higher rev limiter.

[@butunercouk]

I'll ask for a complete cylinder head. Current distributor is my close friend, I think I can get a sample.

[@layersoftruth8115]

Great analysis, thanks to Charlie for sending you the head and thanks to you Matt for the video. The KTM head filter "fix" lol what a joke they obviously know there is a issue with the oil getting to the cam lobes. They can easily correct this manufacturing defect, unfortunately however their reputation with how they handled it not so easy.

[@stevewalker2028]

The fault analysis is unimpeachable, well done Matt. Obvious that those spray jets need a steady supply with good flow and decent pressure, or they'll just uselessly dribble oil which never reaches the cam faces.

[@richardsimpson3792]

I've seen a video of one of these bikes being started without the cover on the head...and there's a patheric dribble of oil out of the jet that doesn't even reach the cam lobe

[@attilavakan1746]

Hey ! great vid! on the topic of why they suspect crap to be getting through the oil filter, I have an idea. During an inspection i was recommended to use the OEM filter instead of the one installed as the OEM has a bypass valve to keep pressure in case the filter gets clogged.

[@cameronmale83]

Glad you two got in touch and smashed them!

[@luddite6239]

"I hope that makes sense..." yes, it makes perfect sense. Fantastic analysis - it must have given you a huge sense of satisfaction to crack this one.

[@daviddemarneffe4210]

Legit question by several commenters: does the nozzle screw all the way down to block the top feed drill hole? You didn't make that part obvious in the video

[@orange1666]

Absolutely , without the jet his assumptions are guess work - the only way to prove his theory is to have a flow test at each exit nozzle all at the same time to see if there is a imbalance of flow/pressure , so all 8 jets in place and readings taken altogether , anything else is simply “i think” which is not good enough especially if you are trying to prove in court . Not to mention he has only one head to draw conclusions on ! To clearly identify the problem you need to establish a pattern with many heads and the background history of each bike , as a moto sport engineer with over 30 years experience at world championship level I am convinced it’s an oil flow / quality issue so he maybe on the right path , obviously the design is not bombproof as there are many examples now and they cannot be all customers neglect , maybe the design is weak and therefore cannot tolerate extremes but there are many high mileage examples now without issue , maybe it’s poor quality control - for sure KTM will now know but don’t want to admit because it’s going to cost them a lot of money , they for sure give limited knowledge to their dealers and tell them to say it’s not any issue as they all say oh that’s the first time I have seen that problem 🤦🏻 , it’s not just KTM most manufacturers are in denial when they don’t have a solution , can’t afford the fix or don’t have the replacement parts ready - I have worked with most of them and know they do this , otherwise their admission would be a nightmare and customers could rightly demand a full refund on their bike/car if an immediate and satisfactory solution could not be delivered . For anyone doing a top end job then I recommend spinning the motor with the rocker cover off - it will be and should be a messy affair but you should see good oil flow and equal flow from each jet onto the cams , this design is tried and tested in their enduro and MX bikes but for some reason is occasionally failing on this model , the flow rate is absolutely critical for good service life , those cams last minutes in an MX bike if the flow is restricted !

[@dirtygarageguy]

@orange1666 this has already been done, there are videos on KZbin... and yes, I would love to have this head for longer, but that's just not possible...

[@rogerwilliams2902]

Must admit, other videos of yours critisizing other channels are over the top, but this one is different. In my view , your description of the fault is very well thought out and described , leaving probably no doubt as to the cause of the cam destruction. So, well done !

[@dirtygarageguy]

Over the top? Thanks for the review.

[@timmybaker206]

Thanks for this video... I am unfortunately an owner of one of these problem engines... Bought brand new and my problems started 15 months ago, at 6000km my clutch has burned out. I was not convinced it was rider related, but nonetheless dealer and KTM pointed finger at me. This bike has been in for 15 warranty claims in the 19 months I have owned it. The most recent being engine overheated and then the oil pressure warranty was persistent. This is after since about last year this time I have been complaining I get the oil pressure warning blimp everytime it starts, sometimes for a second and others for a bit longer however not long enough to get a phone out and take a photo before its gone. Additionally I have has horrible cold start issues and exceptionally noisy engine. Well its at the dealer now and the water pump seal has blown and deposited water into my engine which subsequently forced the issue of checking out the other bits which have been found to have been damaged too. Bike is under warranty (4 months left) and I am waiting to see if they will replace the parts or the engine or give me the middle finger like in the past.... My bike currently has 19600km on the clock...

[@glossblack1098]

Great detective work. It would be good if you could get hold of another example and do that flow test you mentioned, to see any lack of oil flow from the various jets, matches the differences in cam wear. Cheers

[@MrAranhaman]

Very well explained.I do however have one question,did you measured the oil pressure and checked if the oil pump is doing what was supposed to?

[@sk2283]

interesting theory, difficult to say how deep the nozzles seat / if they actually go far enough back to block the passage at the junction - the only real way to confirm this would be to fit some nozzles and test with oil flow really, like you say even a small reduction in oil flow would starve the cams and generate friction & heat = premature wear. good work investigating

[@vincemarshall8550]

good find ! would never assume such a basic design fault in the head ,so new cams would be pointless without alignment , wicked mate

[@wibblywobblyidiotvision]

Do the squirters / jets bottom in their cross drillings, or cross the feed drilling, or what? If they don't bottom, and the jets aren't blocking the cross drilling / drilling intersection, I'm having trouble seeing how the jets are blocking the feed. Not saying you're wrong, mind, it's more a question of how you're explaining it I think.

[@stiffybrian]

Agree with your last conclusion, that any pre-restriction approaching the size of the jet cross section in the supply will reduce the pressure increase at the jet and cause oil to dribble out rather than spray and miss its target. Der, sorry obvious.

[@fuzzy1dk]

afaikt the only way for the jet to cover the cross drill is if it bottoms out in the threaded hole, which I don't see how it could unless they found way to thread a blind hole all the way, what am I missing?

[@prdoohan]

My thoughts too. I've contacted a mechanic I know has done several under warranty and hoping to get a head from him. He's got two old ones he swapped 3mo ago under warranty. If it all works out, I'll bandsaw and mill out the head like Matt intended...

[@dirtygarageguy]

The jet just makes things worse, the main issue is the alignment. The intersection is on the side of the jet hole, not the back.

[@rogercrier9115]

I first came across this squirter system on my Husqvarna FE250, and it scares me no end that the oil can be contaminated with clutch debris and the jet holes are tiny. If they are going to filter the oil supply to the head, they need to make the filter a centrifugal one like Honda does/did with the crank oil on their small bikes. My 2019 125 Monkey has centrifugal filtered oil going to the crank and also the cam where’s the newer monkeys now only have a paper filter☹️ The centrifugal filter collection cavity on these bikes is good for thousands of miles, and is a brilliant idea that has been in existence on Honda C50/70/90 et al since I were a lad………

[@dirtygarageguy]

@rogercrier9115 but there's a 5 micron oil filter... like all bikes today.

[@rogercrier9115]

But surely, if there is a filter blockage and the filter starts bypassing, then any supply to the crank/ head is compromised. A centrifugal filter cannot get blocked! It can get “full” but that would take tens of thousands of miles

[@Mr.Bearded.Mechanic]

There are some theories about the 790/890 cam issues. Like low to no valve clearance/lash, clogged oil squirter(s), and weak/damaged oil pump. People are now trying to change the oil pressure relief valve spring from a 2.5 Bar to a 3.5 Bar one, trying different oils (not Motorex), and more frequent oil changes. This is new to me that the cross drills are not aligned correctly. I have spoken to a dealer mechanic who said that some new/replacement 790 cylinder head was dirty from the manufacturing processes with lots of manufacturing residue/metal dust, and needed to be cleaned thoroughly before being put on the cylinder. The revised ones are clean now. KTM also revised the lifter to a wider one, along with the cylinder head with bigger oil squirters. KTM is now taking goodwill actions on damaged cams even if the bike is out of guarantee. It differs from country to country. I have a 2019 790 Duke (with 13 000 km) so soon I have to peek under the cylinder head cover on what is going on. That little filter screen issue is similar to what Subaru did with the turbo oil feed banjo bolt. Subaru put a little screen on the banjo bolt and over time it killed the turbo because of the lack of lubricant. Also did this with some solenoid valves that actuate cam positions hehe.

[@ritid69]

But does the nozzle screw all the way down to block the top feed drill hole?

[@stevewalker2028]

"KTM is now taking goodwill actions on damaged cams even if the bike is out of guarantee." This was the obvious and necessary solution all along. Have the integrity to say: "Our engines shouldn't be failing like this. There's a clear pattern which points to design or manufacturing error, so we'll own this and put it right" KTM's denialism has hurt their brand reputation. Who would trust them after this?

[@dirtygarageguy]

Yes

[@dirtygarageguy]

The vertical feed hole is drilled after the jet hole. You can see the thread profile intersect the feed hole

[@thediddly]

Cheapest fix for a layman or a workshop would be a countersunk rear oil feed no? I mean yes ktm should take accountability though

[@FatBikeRacer]

The nozzle doesn't go in that far to block off that opening.

[@noggintube]

Doesn't need to fully block it off though, just enough to restrict flow and cause premature wear due to an inadequate oil supply. Shame he has to send it back as would be good to have got some KTM jets and cut it open to see if theory is right. It certainly looks like a very plausible reason and would make sense for this specific failure.

[@justmyself1000]

It's not a matter of how far the nozzle goes in....The hole where the nozzle goes in doesn't line up with the vertical hole that feeds the horizontal hole where the nozzle / jet is screwed in.

[@gregburls3699]

Thanks, Matt! Its fun to watch someone do a job(video) they are well suited for. They have obviously figured it out also,but those people were getting paid by the hour to figure it out. I hope they stand by the mistake and make things right for all,you cant sell something with a built in failure point that fails before you can factor in normal"wear and tear" bs. Auto manufactures have people who go to work everyday to figure out longevity of their parts to help keep them in business(I was told personally by someone whose job is that),but this looks like a design flaw. Oops happen,so make it right ktm.

[@jongreen9113]

A very thoughtful analysis, thank you. thinking on from where you led... Would not increasing the diameter of the vertical feed-drilling by 1-2mm open up the intersection with both of the spray-drillings more easily? At the same time counterboring the back of the jets with a tapered-countersink would reduce obstruction due to the thickness of the threaded collar whilst retaining as much thread surface error as possible.

[@StructEng12]

This definitely seems to be the likely culprit. Also explains why some bikes/cams/lobes are affected while others are fine. Given this alignment issue, add a tiny bit of manufacturing debris in the oil galleys to the mix and the passage cold be nearly completely cut off the oil flow. Doesn't matter how hard the cams are or how often you change your oil, it's not going to matter. The cams are on borrowed time.

[@GadgetMart]

Great video but it makes far more sense to drip oil from above than it does to jet from below.

[@Jonathan-L]

I disagree. Oil squirted under pressure should still reach its target, rather than rely gravity.

[@closedcasketcustoms]

Makes sense, definitely think you're on to something mate. This is 100% an oiling issue and not "soft cams" you can see the affected cams are burnt up just by discoloration of surrounding areas. Not a good look for KTM and abysmal handling of this. From what I've read, they are just adding more surface area for contact. Don't think that's going to solve this issue alone.

[@yorkchris10]

It's the first time I've heard of using squirters on camshafts. I'm always intrigued by how an oil circuit works in an engine.

[@Jonathan-L]

Yes good point Chris. I wonder what other manufactureres have used in their engines over the years.

[@justmyself1000]

Have mercy! Reading many of the comments below....either some didn't listen carefully or are not understanding! I get it! I'll try ....you have a vertical oil feed passageway. Then supposed to be coming off the vertical feed are horizontal passages that feed the jets. The vertical passageway that is feeding the horizontal passageway to the jets are not lined up properly causing the intersection to be partially occluded. Because of this occlusion...the proper volume and pressure of oil that is supposed to be squirted from the jet to the cam is not happening. Great job! This makes 100% total sense! So KTM's dumb stuff about blaming dirt ingestion and/or not proper service intervals is false witness! The wider followers and dumb oil screen in the head is NOT the fix! And their whole thing of not honoring a goodwill warranty because one didn't all their services done at the KTM dealership is more garbage! KTM....now the cause has been found....DO THE RIGHT THING!!!

[@bencodunedin6634]

As several people have stated it depends how deep the base of the jet screws in, if it doesn't bottom out at the down hole but leaves a cavity between base of jet and down drilling a misalignment won't matter

[@justmyself1000]

@@bencodunedin6634 Whether it bottoms out or not....the horizontal passageway is still partially occluded because it does not align with the vertical...the occlusion causes less volume and different pressure.

[@steveleader4570]

@@justmyself1000 And that occlusion will not only restrict flow but the pressure increase caused by the smaller passageway will have the effect of directing the flow that was meant for that particular jet to somewhere else in the head, (path of least resistance) 100% agree with your diagnosis 😊

[@peterdouglas4073]

Wow, that view down the jet hole is a great picture. Instead of two circles meeting. The two drill points meet and form a triangle. Add the it's blocked. Solution 🤔 bottom holes out with an endmill or square off a drill ? Could you re-aline the holes with an endmill, or would there be too much deflection? Q: what is the jet targeted at ? Is actually aimed at the cam lobe or is it hitting the springs/spring cap ?

[@BarryJTaylor]

I dont think the jet thread is long enough to start lessening the size of the opening from the vertical hole. Aligning the intersection as they have would open up a pretty big hole between the vert and squirter passages. Id more be worried about cleaning out all swarf in suc a set up.

[@zweispurmopped]

That makes a load of sense, I agree you found the issue.

[@firestorm755]

Very clearly explained. I think you've found the problem for sure

[@prdoohan]

Is the jet length thread deep enough to interfere with the cross drill hole? Because if it stops short of the hole it would be OK?

[@shortattentionspangarage1312]

YES! He didn't take that measurement before casting blame on KTM.

[@prdoohan]

Until we actually measure up a jet. We don't actually know.

[@ronskisadventuresinbackyar8013]

This video is simply nonsense, and I'm glad you asked the key question. The length of the threads on these jets is 4mm, while the center of the cross-drilled hole is 10mm away, so no interference is possible.

[@richardsimpson3792]

@@ronskisadventuresinbackyar8013 That's not what he said. The jet isn't obstructing the flow, the misaligned intersection of the two bores is. An insufficient volume of oil reaches the jet for the jet to function properly and squirt it onto the cam lobe.

[@MrJeffyjohnson]

Great video. I wonder what “lemon law” looks like in the UK. Really KTM should offer customers to buy these bikes back at the purchase price. I would hate to sink more money and time (even if they reimbursed me) into a bad design I may only get another 10k miles out of. My 2004 Honda hornet 919 just turned over 65k miles and when I did the valve adjustment at 64k the valves were still in spec and had minimal wear

[@Chambers36TheEnter]

Even with this fault fixed the 790 engines suffer with coolant and oil leaks. Then you have the dodgy electronics on them that can randomly stall the bike. They are basically junk. The 790 Adventure was a £10500 bike now they go for as little as £5-£6k with less than 10k miles. The guy was a bit crazy to pay KTM 5K to repair the head in my opinion.

[@Bavenbushcraft]

Are these the engines built by CF Moto? Also, a potential easy fix... Washer around the head of the jet... Then it wouldn't screw down as tightly at the crossdrill intersection and would give more space for the oil?

[@dondle2]

First class analysis bud, good on you.

[@AvenEngineer]

Just watched a YT vid called "Design Holes for Machinability" by adam the machinist. Very instructive content about pitfalls evident in this KTM design.

[@rokerius94]

Very interesting find. I fully agree with the putting the additional sieve to the head oil galley is absolutely stupid “fix”. Eventually KTM is going to have to make some sort of decision about a recall/service campaign. And I’m quite sure that this finding of yours is going to be one; or one of the remedies applied. I don’t own a twin cylinder, but a single cylinder 690 lc4 and I’m still having nightmares about having this camshaft issue eventually. Possibly the cause being the same?? Anyway we’ll see how this problem gets resolved eventually, keeping more noise about these issues puts more pressure on KTM which is good.

[@RichardHinks-c1h]

What year 690 do you have? No known issues on the later engines with cam wear so that's good news for us

[@rokerius94]

@@RichardHinks-c1hsvartpilen 701 my.2019. Actually checked the valve clearance recently when servicing the bike. Light “marks” that could be seen with eye in the cam lobes did caught my attention. However no cam wear, at least not something that could be felt with fingernail. I’m not too worried about it now after check, but I am going to keep checking them in upcoming services just in case. Not sure if the newer lc4 with twin balancer shaft is better. But this is also what I’ve heard

[@nzseagull]

Has to be the oil supply to the cams they just don’t turn to dust like that. I’ve been around motorcycle for ever it’s the 1st time I’ve seen cams in that state. You need that oil wedge to maintain zero friction 😊

[@2Wheels-Adventures]

@2Wheels-Adventures 29 minutes ago Excellent analysis and diagnosis Sir! The cross drilling of the oil passage being perfectly aligned with each other is not important. Remember that we are talking about oil, it is fluid. What is important that the intersection of the cross drilling has no restriction due to the nonblending of the miss aligned cross drilled passage. The flow must stay constant in volume until it reaches the jet nozzle. One must understand Bernoulli's principle where velocity and pressure are inversely proportional to each other. I own many KTMs and very disappointed in the engineering and quality control in their manufacturing process. Is the bottom line answer to the question of outsourcing the manufacturing of what used to be top quality machines, ie like the Boeing aircraft I have worked on for the last 36 years? Just saying, "Wake up KTM."

[@AnonAmouse-em4mf]

excellent stuff matt, thanks.

[@h.nguyen4193]

I think KTM has more than one solution for this problem but their still trying to find the most cost effective way to perform the recall. In the meantime everyone is in limbo on what their decision will be. Replace or recall. I believe the quarterly report was a major facture into the long decisions.

[@NK-dl2nc]

I don't think that the oil feed system is adequate. The labrynth of oil gallerys around fasteners etc is a good idea from a manufacturing perspective but given the flow required to hit the lobes I would say that the gallerys are inadequate. People have suggested increasing jet size, but this would reduce flow to the cam journals as fluid takes the path of least resistance. There have been many instances of journals getting destroyed as well. Let's not overlook the aggressive cam profile. I would say that the followers are poorly designed in they don't have enough contact area on the lobe. This is increasing the contact loads and shearing effect. The oil maybe can't cope with this and so you start to get metal displacement which results in rapid breakdown of the contact surfaces. They should be roller followers. KTM aren't very good at those either from what I remember? Probably better to combine it with a spray bar off the cam cover which would give better lube at low rpm where loadings are high and oil pressures are lower combined with wider followers which would probably give an extra 25% contact area. KTM Ready to Race & REBUILD😂

[@EliteHydronics.]

Excellent video. fire up the lathe matt !

[@esp_explorer]

Great work Matt. Well explained 👍

[@latemnf]

Someone I'm sure has a head they'd be willing to put on the bandsaw. For science. Great job Matt. A cylinder head of course not a human head.

[@prdoohan]

Trying to get my hands on one.... I have 2 lined up that were warranty jobs a few months ago. But will be a month before I can get to them

[@cliftonsr]

I would like to see a comparison of the casting and oil passages with a new head that KTM is replacing them with. I also agree the filter in the cylinder head is really stupid.

[@Slayerofmothers]

I love this breakdown and explanation. It was very easy to understand!

[@wernerxldata]

So in the end you want a complete head with jets and test the oil flow... You should be able to see if some jets fail. Not being aligned holes could be a reason for problems but it doesn't have to be. As long as there's enough oil pressure for the oil to flow through the smaller crossing points there's no problem. But I suspect the boring isn't very consistent, if that's the case there's heads where it all works great and there's some that don't properly feed the oil through the jets. Sounds like it's possible a machine shop can fix such an issue. Is it always the same cam lobes that have the problem or does it differ in cases ?

[@ioandragulescu6063]

I think the problem isn't necessarily the width of the thread of the nozzle but the depth of it. Looks like half a cm or so ? And when it goes in, because the holes are misaligned, it ends up obturating the vertical tube. Now I don't know how deep the horizontal hole is though ... but if it's just slightly longer then the depth of the nozzle thread then well, bingo. Because otherwise, if there's enough space there for the liquid to fill the volume and reach the nozzle, the misalignment won't be an issue. I assume that oil has a reasonable amount of pressure, right?

[@gafrers]

Quality analysis as always. Thanks Charlie

[@brendanmccabe8769]

I can't see how the intersection of the holes has anything to do with the nozzle. That intersection looks to be about 40-50 mm down from the c'bore while the thread on the jet looks like its about 10mm long. The mismatch between the angled, outlet holes and the vertical feed hole may cause an issue but possibly not, presumably the 2 angled holes intersect each other and the vertical hole will cut into the side, the combination of the 3 may give quite a large flow path and may be deliberate. I would have thought all holes would be drilled in a single operation so difficult to get wrong unless they are using third world manufacturing processes. Would be interesting to CAD out the relationship between those passages. Either way the bottom line is there is a manufacturing issue and it should not be down to customers to live with this or prove why failures are happening.

[@wilsonisme1]

Nice explanation . I wonder how many heads have been affected by it. Lot of time putting that right for customers on KTMs part if found to be thousands of them not in alignment. Its always an issue if you cant squirt where you need to or at the right pressure. 😂

[@Boogz-gd3lo]

Maybe screw all the jets into place and compare what pressure each one takes to pump oil through. 🤔

[@richardsimpson3792]

Excellent diagnosis & explanation

[@RobertKehl]

Why couldn’t you just shorten the threads on the jet so it’s not blocking the vertical drilled hole. I could also see if the vertical and the side holes are to far offset that would also limit the cross connection hole.