Part 4- 2017 KTM Bottom End Overhaul- Crankshaft Runout & Truing

This is a series of videos which show how I overhauled the bottom end of my 2017 KTM 250 EXC engine with 456H. In this part I show how I measured the runout and trued my newly rebuilt crankshaft.
Dial Gauge- Mitutoyo 2109SB-10
Dial Gauge Extension (50mm)- Mitutoyo 21AAA259F
Stand- Noga NF61003
2017 KTM 250 EXC with Keihin 38mm + STIC & RK TEK Head
Webshop: www.tokyooffroad.com/
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Facebook: / tokyooffroad

[@essm8443]

If you ever want to buy a used dirt bike, get one off this guy 😅👌

[@a.kq8984]

Indeed

[@EC-xo4ti]

Master Machinist; excellent attention to detail and patient sequential approach to achieving precision, very much benchmark. There isn't another engine rebuilding tutorial filmed on youtube approaching this level. Thank you!

[@vegasromaniac]

dude, love the video, this is way beyond what youtube was designed for , there are like 100 people in the world that are willing to take this task , you are quite unique !

[@jerseyjeeper1575]

Says a 2T hater... 😂

[@Dsm152]

100 people in the world that can true a crankshaft? Lol where did you pull that fact from? You’re a flog.

[@daneng2335]

Finally someone who knows how to do it right! Very good instruction video!

[@mixalis6168]

He is by far the best on KZbin and on any social media!!

[@TheMillwright1980]

Glad to see you pre-loaded your indicators equally at .367" 👍

[@milspec1]

Really glad I found your crank rod replacement videos. Excellent work.

[@TokyoOffroad]

Pleased to hear that you enjoyed the video.

[@kimojon9665]

I've never seen anything like that, just so impressive and quite beautiful! Amazing instructor. Now I know exactly what's in the bottom end of my 2019 XC-W 300 and how well it's built.

[@meckanicall]

The very best crankshaft truing video on KZbin. Many thanks

[@jimmydacey3]

Mark, I can't tell you how much I enjoy your videos, and your products! I have one of your oil drain tools for my KTM, works like a charm! Thank you, and keep 'em coming buddy!!

[@TokyoOffroad]

Will do and thank you. Pleased that you enjoy the videos...

[@AndrewBoundy]

Excellent video. I'll never do this to be honest, but knowing how and why is great knowledge to have - even if only to talk with the shop or provider doing the work. The investment vs. requirement doesn't work for us regular fellas, but for shops and experts - I can see it does. Thanks for making these videos which must take a lot of time.

[@themotobarn702]

My gosh, this was so well done and extremely thorough! I'd like to try my hand at this sometime. Thank you for being so detailed. Great work!

[@jamesbramblett3346]

This video is ACE. Thanks. You sir are an excellent instructor!!🙌🏻

[@TokyoOffroad]

Thanks and pleased you enjoyed the video!

[@MetaloMan007]

The best tutorial about crankshaft truing. Thank you very much great work.

[@R.B_B]

Great video!! Technical videos about 2 stroke stuff always is good.

[@alangreen5858]

Excellent video; I have just used your advice and technique to true up an old maico crank .Got it to 0.02 mm. Once you get over the apprehension of the seemingly brutal technique that is needed and develop a feel for how much to hammer or squeeze the halves it doesn't take too long about 20 to 30 mins in my case. Thank you.

[@tangjason6382]

Yap , REAL Professional skill ......., well done ! Your test gauges also are REAL using in factory , really nice and well done !!

[@syncrosimon]

This is such a well explained resource, good effort and thanks👍🇬🇧🇬🇧🇬🇧

[@TokyoOffroad]

Thanks! I'm pleased that you enjoyed it. It's quite a bit of work to make the videos, but makes me happy if people find them interesting.

[@kungdewe3888]

@@TokyoOffroad Boss ask WhatsApp number

[@aaronjackson3631]

You are perfectionist!

[@jerseyjeeper1575]

Thank you for this. Much appreciated.

[@kelceyv]

Nice work!!!!

[@vince5946]

Great video. My OCD would never let me leave until I was at .0001" LOL.

[@Wyrmidion]

thanks to this video i may actually dare to tear down and rebuild my 450 SX-F myself since it's supposed to be very similar :)

[@Avantone]

Thank you - now saved for reference!

[@fabiofadda6650]

Thank you for editing such a detailed video. Not sure at the workshop they waste so much time!

[@TokyoOffroad]

Pleased that you enjoyed the video. With these videos my aim is to include details of all the steps, tips and tools required, without fluff. Some people like them, others don't, but I know no matter what you do not everyone is going to like it...

[@fabiofadda6650]

@@TokyoOffroad of course I wrote "waste" ironically! You did the meticulous job as any professional should. Crank balancing and run-out accuracy affect high performance engine such as modern 2 and 4 stroke. Keep up with your sharing, thank you

[@pacop3759]

good job!

[@RaksasaMentawai]

Awesomeness ❤

[@TokyoOffroad]

Pleased to hear that you enjoyed the video

[@benyaminnaseri6612]

Very nice .

[@goodboyringo9716]

The run out part would stop me dead because of the tools needed but nice to see how you are doing it. I'm wondering if a new KTM crank assembly would be trued up as good as you did this crank.

[@Chris-uh3cm]

Aweosme vid 👏

[@TokyoOffroad]

Pleased that you enjoyed it

[@brianp7938]

You lost me after "Part 4" - amazing video though, so well done.

[@seanwilson5429]

Thank you for an awesome video. I am in the process of rebuilding my 2013 KTM 250 EXC with around 500 hours. I live (now stuck) in Vietnam and have to do all work myself, but never did a bottom end (that doesn't sound right...). Anyway, I shipped in a Cylinder Works Big Bore and Hot Rods Stroker bottom end kit and now kicking myself for not buying OEM after seeing your video. Unless there is easier way, I don't think I will be able to do measure the run out or end play. The kit didn't come with any compensating disks and there is one on the left side of the old shaft. Should I install a new compensating disk of same size as old on new shaft and pray that everything will be ok? Also, it didn't come with the woodruff keys and there is little on internet showing how to correctly put them in. Any help is greatly appreciated.

[@sbennettyt]

Blows my mind that cranks are make this way. How does it not fly apart????

[@giwtwm]

damn mate i wish you were close so i can get my crank worked professionally

[@palmpilote]

Good job and nice video. I am curious about if the whole new crankshaft from the KTM is within this limit. It seems the truing may be changed easily when transporting from the KTM factory to the customer.

[@TokyoOffroad]

Good point. If the crankshaft was dropped, yes it's possible. If you can measure the runout before installation to check it would be best...

[@krp6147]

Sweet 😎👌🇬🇧

[@grant31781]

What keeps the crank from moving out of adjustment once its back in the engine? It doesn't seem like it takes that much force to change the alignment.

[@alfonsoguzman2099]

Would you recommend welding the pin to prevent it from happening again?

[@PurpleShadowDragon]

did the hit the flywheel side crank web at directly above when the right side gauge read high to lower the reading to better spec?

[@roncoburn7771]

when you hit the web or press them together don't the flywheel just come right back out of true again after time. I work on Harleys so i was just curious .

[@paulwilliamson8684]

brilliant ,you certainly know your shit, just hope it ran again lol

[@2stroke1971]

I really have a conceptual problem with pinch and spread. The crank I am working on (the first one I have attempted) shows that it is pinched. Im getting an even needle swing now after hitting it a few times with my brass hammer to move the webs around to match each other......but the needles move .005-.006 high with the pin down, so "pinched". I have beat it with an aluminum 1/2 inch rod with the tip ground into a wedge and it is not budging a bit after several good smacks. What about a 10 ton press fit pin is going to move to "adjust" pinch and spread? I get the concept...but something would have to MOVE, or GIVE in order for the distance between one side of the webs and the other to be affected. The pin is not gonna bend. There is no clearance between the pin and the webs to permit the pin to move, or the webs to move on the pin perpendicularly to the pin. I mean really. ????????????? Ill try making a wider wedge tool at some point.... but still...an assembly such as my crank (from a 1970 kawasaki) should not have ANY room to flex or move in the way it would seem to need to. What moves with pinch or spread? Something would have to deform or bend in my estimation in order to change it.

[@endurodz]

When truing my crankshaft an expert says that using a lathe is not the best way because the rotating side has bearings and there is always play in bearings. But like always a wounderfull videos there, wish i had this when i rebuilt my engine bottom-end last year

[@jaker1160]

How does your expert suggest that it be trued?

[@TokyoOffroad]

A bench center is best for runout measurement, but I don’t own one. If anyone has one which they don’t need I’ll gladly accept it. My experience is using dead centers in the lathe works well and my runout measurements were very repeatable. Note the the lathe head (which has two opposing taper bearings with preload) does not rotate during the measurement and is simply holding the dead center in place. If the inaccuracy the lathe head bearing was introducing had been large I would not have been able to repeatedly measure the final runout on the clutch side of less than 1um. As such I do not consider the lathe head bearing (on my lathe) introduces enough error to be concerned about in this application.

[@endurodz]

@@jaker1160 by luck his work is calibriate and true rotating equipement and he have all tools to do it. We use a bench center we work in the same turbine maintenance company

[@endurodz]

@@TokyoOffroad yes i am very impressed with the result you had. Mine was near 1μm too

[@sbennettyt]

I totally understand the twist adjustment. But why the vise squeeze adjustment? Is this because the press fit can be cocked? I guess that must be the answer.

[@TokyoOffroad]

Yes, that's right. Note that the dimensions being measured are very small...

[@tedmagnum6968]

Excellent video. But how much do you trust your lathe to use as dead centres for such a small run out ?. The run out on a crank is generally only measured on the bearings journals..

[@TokyoOffroad]

The height and offset of the dead centers relative to the lathe bed, or relative to each other are not critical for this measurement. What is very important is that the dead centers don't move during the measurement and provide a fixed, stable reference axis for the crank shaft to rotate about. The lathe is very stiff which minimizes any movement of the centers. The crank run out readings I see when using my lathe in this way are very repeatable, suggesting the measurement error due to the dead centers moving are insignificant.

[@barkeep25]

Sent mine out for rebuild to crankworks here in the states. Should I test mine for run out before installing when I get it back?

[@TokyoOffroad]

If you have the necessary equipment to test the runout then yes, it’s a good idea to measure before installing it.

[@carlosaguilar4172]

Muy bien explicado, Uno de los cigüeñales de motocicl eta mas pequeños que yo llegue a rectificar y valancear haste el mas grande que me toco rectificar en Mexico en los años 80s el mas grande fue un D,13,000 6 cilindros en linea, 6 pies de Altura. Saludos cordiales desde Dallas.Tx...🤚👋🤚👋

[@MikheilZhizhilashvili]

Hi Mark, Please let me know how did you adjust dial gauges at zero, which position is there start point and how you dicade it that was really zero and start point. Thanks,

[@TokyoOffroad]

The absolute adjustment of the dial indicators is not important. For the video I had them adjusted so the zero was approximately in the middle as it's easier to understand what's going on. But its the peak to peak reading of each gauge which is important and they don't need to be zeroed to measure this.

[@MikheilZhizhilashvili]

@@TokyoOffroad Clear, Thanks a lot!

[@neiljohnson9686]

So how important is the alignment of the centers to each other? I have an old craftsman lathe and my crank will fit on it…I’m sure it’s not the most precise alignment in the world and I will try to put centers in the Chuck and the tail and see if I can get them to touch point to point…. Other than that I thought of building a stand with some long threaded rods that ended in a point (points made on a big lathe at work) ….then supporting the crank between those. I’d guess since the crank halves each have an indicator on them it wouldn’t matter if the crank was off level end to end or nearer or further left to right ??

[@daviddanielstephenson2833]

Any decent lathe can act as a set of bench centres, as long as it is not worn out, remove the chuck and use a solid dead centre point, same as the tail stock, try to lock the head stock so it cannot turn, this will stop any end float that might be there, or buy a set of bench centres for maximum stabiity.

[@mxcollin95]

As you begin to squeeze the crank webs in a vise wouldn’t it be more beneficial to somehow have a dial indicators setup between the vise grips/crank webs so that you can accurately measure the precise squeezing moving required by the vise in order to push the crank webs together in a controlled, target amount in order to maintain the utmost precision in crank web alignment process? This seems like it’d be a much better and a more accurate way to push the crank webs into their exact desired position as opposed to just re-squeezing the crank webs in a trial and error fashion which may leads to the weakening of the crank pressfit joints. Do you think this is how the factory teams go about dialing in their cranks for maximum precision. I would love to get your thoughts on the approach I mentioned as I am a completely new engine builder hoping to do the best job I possibly can. Any guidance would be hugely appreciated!!! 👍 (sorry if these are dumb questions!)

[@TokyoOffroad]

The ultimate goal is to press the crank webs into the correct position first time and not require truing afterwards. A good jig really helps with this. However, the runout spec is pretty tight so you'd have to be quite lucky to hit the spec with no adjustments. The adjustments required are very small tweaks. You could certainly set up a dial indicator to measure the amount of squeeze in the vise (if that's the adjustment you need to make) and would need to calculate the scaling factor. However, I do it by feel, a little bit at a time, trial and error, remeasuring the runout after each adjustment as shown in the video and it really doesn't take that long.

[@sidecarbod1441]

Very interesting! I've been around 2 strokes for most of my life, I find it hard to believe that the crank does not just go out of true as soon as the engine is fired up! I used to run a 'mega tuned' RD 350 LC on the road, the crank had to be welded up after being trued in order to keep it in spec. (Although I suspect the welding process may have messed up the run out to a degree). You should have given the crank one final whack with the hammer to get rid of that 18 micron runout!...Easy for me to say whilst sipping a cup of tea.

[@sidecarbod1441]

@Northwest Connection I don't think the casing would have enough 'stiffness' to hold the crank true, for starters the bearings actually have a clearance value (could be C3 or C2, I can't remember which). I have cranks twist whilst they are inside an engine due to a failure of one sort or another (piston seizure, that sort of thing). I had a crank even break the welds that were holding it true when a drive chain snapped which jammed up the gearbox, it broke two teeth in the gearbox and totally twisted the crank up. I was young and stupid, I should not have let the drive chain get so warn out, I should have replaced it. Anyway my point is that the cases won't hold a crank true.

[@mxcollin95]

Great video!!! Question, if starting the truing process with a new crank, would it be best to start with getting the webs aligned as perfectly as possible in terms of being in aligned rotationally first, then attacking the parallelism of the webs next?

[@TokyoOffroad]

My recommendation is the same as I showed in the video and start the truing with whatever is the largest type of mis-alignment. Small corrections and a remeasuring runout is key to monitor your progress.

[@mxcollin95]

@@TokyoOffroad thanks for your responses! I’ve really enjoyed and learned from your videos! I really like your cardboard bolt template idea…super simple and super effective. 👏 Also, I really like how meticulous and organized you are when executing your maintenance work and also how you explain things very clearly yet succinctly. It drives me nuts in videos when someone explains the right way to do things and then immediately skips doing things the right way saying that “it’s not really required this time.” All these pro qualities are actually hard to find these days in good KZbin tech videos so well done sir. 👍 With so much precision, are you a machinist by trade?

[@TokyoOffroad]

@@mxcollin95 Pleased that you enjoy the videos. I'm an Electronic Engineer by trade.

[@linus5699]

Maybe I am an idiot, but in the end, clutch side almost 0,0, but the flywheel side has runout. How do you adjust when 1 side has runout, and the other does not?

[@naveedaka]

Will the trying required be opposite if dial indicator is kept at the edge of the shaft in some other Crank shaft??

[@naveedaka]

Truing"

[@TokyoOffroad]

No, it'll still be the same required method. However, the measured runout will get smaller the closer you get to the supports. For this reason, as discussed in the video, it's best to take measurements as close to the crank shells as possible as the measured runout will be larger.

[@michail1963]

what kind of metal wedge can i use not to damage the crank?

[@TokyoOffroad]

Aluminum works well

[@Drottninggatan2017]

Now you must be aware that the centers in the shaft can be damaged. If someone has hit the end of the shaft or used a puller on it then there can be a damage to the actual center.

[@TokyoOffroad]

Yes, if someone has been hammering on the end of the crankshaft the centers could get damaged. But IMO, there is never a good reason to hammer on the end of the crankshaft, so this should be a non-issue for most.

[@Halikati-mu5sc]

✌✌✌

[@250race]

Thank you for showing all of us how these cranks cum when we buy a new Chinese crank from Wiseco hot rod all ways buy a Stock oem crank And your gap should be no bigger than .025

[@TokyoOffroad]

This is all stock KTM OEM parts as discussed when I rebuilt the crankshaft in part 3. What gap (0.025) are you talking about and what units (mm, or inch)? If you're talking about the conrod axial play, I measured that in Part 3 and it was greater than 0.6mm (0.0236") and less than 0.7mm (0.0276") which is within the KTM spec (0.6mm to 0.7mm). I remeasured this after truing and it hadn't changed.

[@JohnDoe-iu5xi]

9:26 That's strange. I would think intuitively that if the Webs were spread opposite of the pin (away) then there would be a high reading when the pin is at the top and low reading when the pin is at the bottom. It looks like the Web spread away from the pin would angle the crank down not upward... wth.

[@TokyoOffroad]

If the pin is at the top and the webs spread out away from the pin the the crank will be high on both sides if measured from the top (as in the video). If you have two set squares it’s easy to visualize what’s happening...

[@JohnDoe-iu5xi]

@@TokyoOffroad I just made a crude drawing. I think I see it. So when the pin is at the bottom the crank ends would flex the pin up?

[@250race]

Is this the first time you ever put a dial indicator on a crank to see what the run-out was? It should be at .00 on both side.less bearings and less chance to have a leaky crank seals

[@TokyoOffroad]

I'm not sure what units you are talking about (mm, or inch)? All measurements in the video were metric. If converted to inches the clutch side runout was 0.00004" (1um) and the flywheel side was 0.0007" (18um). The KTM runout spec is

[@llewvirtue861]

No need to remove the crank, use A G clamp

[@in-sani-ti]

this is where I dont understand a word he's saying.. but not to say that this is not a good video..

[@cinogilo6362]

How to get left right 0 straight