How To - Rebuild a KTM TBI Top End

Jeff walks us through a top end rebuild for the TBI KTM, Husqvarna and Gas Gas two stroke dirt bikes.
Find the parts you need for your rebuild at Slavens Racing.
Vertex Pistons: slavensracing.com/?s=vertex+p...
EZ Top End Kits: slavensracing.com/shop/ez-top...
High Compression Cylinder Heads: slavensracing.com/?s=cylinder...

[@leootero6101]

Thank you for the video. Love hearing your 30 year thoughts on important and not so important things. And then the advice like Putting a new piston in an old hole…nothing to break in. Thanks again

[@ryanstewart1521]

Looking forward to seeing a power valve rebuild video on a tbi, haven’t found one on KZbin yet.

[@bobbywinn6548]

Excellent video!! Thanks again for taking time to share!!

[@slaverace1]

Thank you.

[@Jitkoa1]

The most impressive thing for me is how clean the bike is. I have done a lot of engines but wasn't able to get it as clean as new.

[@slaverace1]

Hello: I use Gunk spray on the engine.

[@philipsmith6152]

Great video, luv the condensed version and the no BS advise about break-in, torque settings etc 👍

[@slaverace1]

Thank you.

[@byronstuck8875]

Great video quality (lighting, tracking your work, etc) ... thanks for the improvement ... and thank the guy that helped you too!

[@slaverace1]

You're welcome.

[@olliechristopher467]

You are one of the good guys Jeff. Even though I'm on a Beta, I find your tech videos very helpful. I don't think the average viewer remembers all those engines you ported and built way back when. Hundreds if not thousands. It's mind blowing. I figure you are semi retired so I would call this a "retirement project". LOL Thanks my man!! I'm pausing it now and coming back to it.

[@slaverace1]

Thank you.

[@code4performance]

Thank you, Jeff!

[@slaverace1]

You're welcome.

[@Danman1972]

Great video! Just a note. I love the old school wooden handle screwdriver. At one point or another I think everyone over the age of 40 had a set of those! I think they were in my first tool box that I got from my Dad. I have a new driver set, but I think one of those is in my bin of "tools I can abuse". I can bend or grind on them for specific things or just use in an abusive way to beat on. My gas gas didn't come with the plugs, but I bought them. The factory air filter wash cover has little molded cutouts to store them in the ridge which is nice. Not a torquealollic, but as long as you don't make the wrench handle any longer you can use an adapter without math. The "bottle opener" in the KTM tool kit is actually for that. Just put the wrench end 90 degrees to the handle and its done... that it. You didn't change the leverage on the wrench no issues.

[@slaverace1]

Thank you. I still prefer the wood over plastic.

[@CreekLifeTV]

Greatly appreciate the video , thanks! Ride on!

[@slaverace1]

You are welcome.

[@hoosk125-wm5bp]

Dr. J in the house. Nice. Old guys rule (I'm 64 on a '23 TX300) Good supplemental visual to the Factory Manual. Especially break-in on a used motor. Couple fast-slow heat cycles, burp the head, she's ready. Never runs better than "new". Good advice on the Plated bore recon. Leave it the heck alone. Clean up with SB is OK, IF, ya have the jug completely bare first. Never try to [hone] it- cuz ya can't at home. Ya just can't. Plain n simple, lots of reasons, and ya just dont have "the machine" or the tech to do it. Got some allum in there? Drops of muriatic take it away, completely, SB, 3x wash in hot soapy water, paper towel test, re-assemble. If it's scored or damaged, replate or replace. You simply cannot save a plated bore at home no matter what once it's boogered (finger nail test), period. Jeff-O is doin it....still. You young guns? Take a note. Braaaaaap!

[@slaverace1]

Thank you.

[@richardhartley1705]

Nice one 👍

[@slaverace1]

Thank you.

[@KyleShane]

thank you , for covering the piston sizing A or B , I am guessing once you get the max time on the B size piston that the next step is to have the cylinder recoated and go back to a A size , ?

[@slaverace1]

Hello Kyle: When your cylinder bore specs become out of tolerance, go back to the A piston size.

[@hkk210]

Thanks for a great video! I learned two things: How to change the top end AND not to buy a used bike that someone else have changed the top end 😅

[@slaverace1]

Glad to help.

[@DDRDK]

@Slavensracing so your ring gap inwas told the 300s need .30mm-.40mm gap I think it was. Mine from the factory were .25-28mm and I thought that was a bit tight but you're saying .12-.25 should be okay?

[@The_Snowbike_Channel]

The KTM manual is vague and says .40mm or less. Vertex has a tighter tolerance recommendation. I treat the .40mm as a absolute out of spec threshold.

[@DDRDK]

@@The_Snowbike_Channel I was worried but been riding the piss out of it and it's been the great. Crazy bottom end with a tsp medium head, IRK, tune, and Z set to zero with some C12/90 mix. So much bottom end I had to tune it back down a bit it's almost unruly.

[@slaverace1]

Hello: I said to set it at .012" to .014". Those are thousandths of an inch, not metric.

[@shaneburesh9173]

Power valve motor just goes back on straight away? Probably suggest “resetting” power valve with wake up dongle? Thanks for vid!

[@hoosk125-wm5bp]

If ya don't mess with the PV, you MAY be OK, but just check/reset anyways...take 2 mins. It's easier than filling the tank. Braaap!

[@bushhboii70]

​@@hoosk125-wm5bp What if i dont reset the power valve

[@bushhboii70]

​@@hoosk125-wm5bp What if i dont reset the power valve

[@tomjoad4168]

On the power valve actuator, is it possible to remove it and tie it out of the way without unplugging it? I seem to recall that it would cause an FI light flash when plugged back in. I’ve had two updates since buying the bike in 10/22 so that issue might have been rectified by now. Thanks

[@slaverace1]

Hello Tom: I think it's possible. I unplugged it and had no negative consequences.

[@kristinchrishadley936]

Do you ever check the deck height or piston throw , squish, etc.? I understand that the KTM spec is 0 “zero” above the deck.

[@slaverace1]

Hello: From the factory they have a zero deck, but I often change that spec for increased low-end torque.

[@mark_Hershey]

You said your doing another vid and using the piston in it, would that be by chance a vid on the 300 piston skirt thing?

[@slaverace1]

Hello Mark: Yes, stay tuned please.

[@mark_Hershey]

@@slaverace1good, my 2023 300xc with 28 hr is bogging bad.

[@waynemodesitt3445]

Jeff, would the silicone use on the case seams be the same for a 19 KTM 250XC? I didn't notice any the last time I did the top end. Haven't had any issues with coolant leaking.

[@slaverace1]

Yes, it should be done on you XC.

[@Mostviews111]

Don't do it.

[@Freestylematt139]

Jeff - any advice on dissembling the power valve? Ktm refuses to admit their faulty cylinder issues that many have encountered and now I am forced to replace the cylinder. Top end is straight forward, but now I have to swap over all the power valve parts. Older models were not bad. No videos or info out there on how to do the new ones.

[@slaverace1]

Hello: Sorry, I have not yet made that video and probably won't until winter. What are you calling "faulty cylinder issues"? We have not encountered any issues.

[@Freestylematt139]

@@slaverace1 Jeff, cracked cylinders. There are many people on 250’s and 300’s with the issue and elko cylinders. There’s an entire fb group that has many people with the problem. Some have been lucky enough to get a good faith warranty. Ktm/husqvarna denied replacing mine twice. Bike has been eating coolant since the first 5-10 hours. Only has 40 now. Ktm claims on the 23+ models they won’t even consider helping you unless you change your top end at the “new” intervals of every 15 hours which is insanity. I am happy to send you photos of what I am talking about as well as proof from many others. I personally know a shop owner here in Denver/littleton area that had the same exact problem. Our cylinders are cracked in almost identical along with everyone else. The water jack ports get hairline cracks causing back pressure in the coolant system and coolant goes out the overflow. It doesn’t get past the first inner oring under the head so bike still runs fine. I documented everything in addition to fay Myers here where I bought it brand new. They still told me and the dealer to pound sand.

[@lketter450]

​@@Freestylematt139I have a 23 TX300 with a cracked cylinder. Where did you source your new cylinder from?

[@oldvet79]

Quick question I am doin a 40hr top end on a 300SX, I noticed you didn't rebuild the power valve, any reason? What would you recommend for when to rebuild?

[@slaverace1]

Hello Old Vet: I did not service my PVs because the engine has low hours and I use Amsoil Saber @ 100:1 and it does not leave much carbon. If you like to constantly over-rev like many MXers, 40-50 hours is a good service interval. If you run it at low and mid RPMs you could extend the service intervals to 75-100 hours. For MX applications (high revving) we recommend the Wossner forged piston. slavensracing.com/shop/wossner-top-end-rebuild-kit-for-ktm-hqv-gg-250-300-tbi/

[@Rubberducky95]

Would you recommend removing the oil injection system on the xcw models? Kinda on the fence about it.

[@slaverace1]

Hello: I removed mine to eliminate a possible failure point. slavensracing.com/shop/tpi-tbi-oil-filler-removal-kit-for-ktm-hqv-gg/

[@Jay3809]

Isn’t the .40mm base gasket going to reduce the squish to much? What squish do you end up with on that base gasket?

[@slaverace1]

Hello: If you have an O.E.M. head the squish is approximately .080", which gives you plenty of room to make changes. Mine has an aftermarket head insert but still had room for improvement for the high elevation I ride.

[@SwormCycles]

When would you want to use a C piston? Thanks.

[@slaverace1]

Hello: Usually if you need a C piston for correct clearance, you need to have it replated.

[@grutzmac]

do you notice any difference in engine performance after pulling the injection system off?

[@slaverace1]

Hello: The oil injection has nothing to do with performance.

[@motofamily461]

Jeff I have a question for you. You said you did an oil delete and run 100:1 on your gas oil mixture. I did an oil delete on my 21 Husqvarna TX300i TPI and did a split injector relocation kit. I run 60:1 with no oil at the pipe. Is that ok?

[@hoosk125-wm5bp]

If ya make a drastic change to the "envelope"? Always test it and verify it. Read the plug, yank the pipe, check the Ex side of the piston. Trail ride? Motul 710 50:1, Full race? Motul 800 32-45:1. More oil = leaner AF ratio. Test n tune. Verify it. It's up to YOU. Braaaaaap!

[@motofamily461]

Ok. I’m a little confused. If I’m running 60:1 which is more oil than 50:1 it’s running leaner instead of rich. I thought more oil was ok as long as it’s not pouring out the back of the pipe. How does he run 100:1 wouldn’t that be a bunch of oil? I use to run my old carbureted 2 stokes 40:1.

[@motofamily461]

Sorry I got that backwards 50:1 is more oil. My bad.

[@hoosk125-wm5bp]

@@motofamily461 no worries. The dif between 50 and 60:1 is minor unless one is on the very cusp of lean. If my bikes are a bit fuel rich, but running spot on otherwise with no mechanical issues, I'll add more oil to the mix to get the plug color where I want it (fine point tuning) and re-test 3 times to verify. Amsoil is one of a couple if not the only oil maker recomending100:1 for small engines (chain saws etc) and super slow use trail bikes. I would not use that ratio for anything other than first gear all day HE stuff. I use Motul 710 for trail/HE or 800 for fast/race exclusively. Never scuffed a piston or bore with it. Super clean and super slick stuff. Regardless- Just read the plug, ignore the spooge, do what works for your engine/riding conditions, not someone else's. Unless you are track or wfo XC racing, trail riding will usually result in some spooge when the pipe/crank case loads up then gets cleaned out wfo. Re-packing your muffler often helps control it. Spooge is simply a fact of life on most 2T's if one is not wfo on the pipe all the time. If your setup is clean and the plug reads good/safe, you got it right...Enjoy! Braaaap!

[@motofamily461]

Thanks for the help.

[@davidgrunklee8407]

Isn't a forged piston better than cast?

[@slaverace1]

Not necessarily. Both have their strengths and weaknesses. I have a video in the queue about forged and cast pistons. Please stay tuned.

[@eamh2002]

I wonder why KTM uses the flimsy upper end on their rods, a 2002 300 is fully closed with no holes and works great. Very sturdy.

[@slaverace1]

Hello: Slotted rods (for more lubrication) have been used for many years on many brands without negative consequences.

[@chestertownelectric6290]

Why are rods copper plated?

[@slaverace1]

Hello: Copper draws heat away from the base metal it is clad to.