Hey guys I'm in the process of shimming the crank after I got it rebuilt and now I'm running into 2 issues. First of all, it says To shim only on the ignition side in the manual. That doesn't seem to make any sense to me but maybe that I'm wrong. Anyway the point is I figured out that I need .5mm worth of shim on the crank. Would it be OK to add a .30mm shim on the ignition side and two .10mm on the right side? Also one of the .10mm shim has a dent in it can I still use it? Here's a pic
i didnt notice motor type or size but it may not matter as it relates to my general answer. your bent shim in photo should not be reused as the kinked bent area will be thicker than surrounding surface. shim has to be flat. you cannot hammer it flat again(trust me here) once its kinked its no longer flat and true.bent metal gets work hardened when bent,and reforming it by hammering it flat just stretches the surrounding metal. and now your round shim is egg shaped and not round. and if it did fit in the bore again it is still not flat and true.
you should also follow manual instructions exactly as it relates to shim placement unless you can be sure your method is correct. there may be a reason the lateral movement is only supposed to adjust in one direction.
i can think of lots of reasons why the engineers may have suggested this procedure (internal clearances, ignition rotor alignment, incorrect bearing thrust transfer..)but i wouldnt want to be the one to experiment unless i was sure i had all that stuff figured out first. i would suggest you play the safe bet and do it their way.
good luck with your motor work.
i didnt notice motor type or size but it may not matter as it relates to my general answer. your bent shim in photo should not be reused as the kinked bent area will be thicker than surrounding surface. shim has to be flat. you cannot hammer it flat again(trust me here) once its kinked its no longer flat and true.bent metal gets work hardened when bent,and reforming it by hammering it flat just stretches the surrounding metal. and now your round shim is egg shaped and not round. and if it did fit in the bore again it is still not flat and true.
you should also follow manual instructions exactly as it relates to shim placement unless you can be sure your method is correct. there may be a reason the lateral movement is only supposed to adjust in one direction.
i can think of lots of reasons why the engineers may have suggested this procedure (internal clearances, ignition rotor alignment, incorrect bearing thrust transfer..)but i wouldnt want to be the one to experiment unless i was sure i had all that stuff figured out first. i would suggest you play the safe bet and do it their way.
good luck with your motor work.
Bike is a 250sxf. I just gave my ktm dealer a call and he said the exact same thing than you. I ordered a new shim at the same time. What's weird about shimming only one side of the crank is that the bike came shimmed equally on both sides from the factory so it's like if ktm's service manuals and factory builders were not working together...
I tend to think as you did. If I found shims on both sides I would be inclined to return them.. correct?? But here is a lesson I learned. Your factory may have had a production run of out of tolerance parts purchased and the cheap *** bean counters and engineers got together and say use what ya got and make it work, thus you got extra shim to make it fit. And the replacement parts division and aftermarket suppliers make the part to correct tolerance. And then we get a post that starts with “my new crank turns hard” or
“My rebuilt motor ran great until....” This was learned by experience with British bikes during their dying days when they had poor quality control and a bike built on Monday afternoon couldn’t interchange parts with monday mornings production. You can’t always trust those manufacturers to care about quality when it cost their profits, I’m not sure of KTMs reason to do this to this motor. Just sayin
You've got a point there. I'll rebuild the engine as per the manual says. I've seen numerous of the posts that you mentionned and it never happened to me and there's no way that I'll let that happen. I'm new to ktm as this is my first one and I believe there's no better way to learn a new brand than stripping the whole bike and rebuilding everything so that you know how it's put together. BTW thanks for the input.
I know it’s a old post but I’ve got the same on my 09 ktm 250 sxf.shims equal on both sides! so was unsure if when I rebuilt the crank with new prox to put the same shims on but my manual only says to use compensating disks if the axial clearance is too large??♂ Is this what the shims are for?
Cheers
If the space in your engine cases from one bearing shoulder to the other side shoulder is larger than the crank bearing shoulder you would add the shims as outlined in your instructions. It seems to want you to add shims only to ignition side only if needed. Your original crank may be slightly different dimensionally and this could explain one reason why you found yours set differently. I would be comfortable installing it as per your included instructions, but if you wanted to be certain, maybe call your customer service tech line of your crank kit to verify before installation. If shims are required you can use a smear of grease in the bearing bore to hold it in during installation. Grease will not hurt anything inside motor
I have on old road 4 strokers "cheated" and added shims on the outside of the bearing after the engine is reassambled and I find that after all is assembled I am not happy with the sideway movement of the crank. Have not had any issues as result.
Clearly an old Honda V twin, where the parts are heavier and bigger and that on the road would run around 3 - 4,000 revs, is a different situation than a racing engine that revs to over 10,000 revs. I wonder how the wear is moved if one shims a racing crank on only one side instead on both sides. Logic would say that by having the conrod always being more on one side of the piston would change how the piston rubs the cylinder. But perhaps a minor shimming will not affect this that much?
The shim is required in some instances to restore bearing end play clearance. Often split equally to both ends but this instruction posted here indicated a preference to ignition side case. I suspect this could be the suppliers method of using one similar part to satisfy several applications. This was common in the 70s when one rod kit would fit several engines with the prescribed thrust washers. I think the RM and CR125s shared a rod and big end bearing kit and included instructions for both.
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