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Discussion Starter #1
Last practice session I heard my bottom end get a little noisey. I pulled it in and shut it down right away. I tore it down and found I lunched the clutch side bearing. This is the second time. First time the crank pin twisted. I had it welded and trued, and it's lasted well over a year of riding about 2 to 3 practice days a month.
I was suprised at the uniformity.
I'll have it checked for twist, but the welds are clean.





 

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Yes, what engine size? Do you know what crank axial play was whan installed? Before dissassembly? Seems to me like the cranks spread. Measure width of crank webs at pin and straight across from pin. Welding does help this though. Has the piston touched the head? Maybe you have just established the service interval for main bearings. Do you have a guess at time on these bearings? Is there a ball or roller on the left side?
 

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Discussion Starter #6
It's a 450, stock setup. There is no other damge to anything. The webs are straight. The crank twisted after it's first 12 hours, and KTM techs rebuilt it after having the crank welded and trued. I cant say what the endplay was when they assembled it, but it was zero upon disassembly. They wont be touching it this time. I found three items they did wrong, so I'll be doing this build. My riding is mostly kart tracks, not a lot of time over on the same side. The tracks I run mix it up a lot. I'm glad I heard it and got it shut down before any real damage occured. This is getting off cheap.
 

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Same thing happened to my 525 after installing home made big bore kit, porting and a cam. I hav'nt had another bearing failure since the first time about 40 hrs ago but I dont ride road courses with long sweepers anymore. Ktm rebuilds are pretty easy if you buy a few tools. I have done mine several times. Good luck. Took mine to local shop for them to listen they said it was definiatly not a bearing and to keep running it till it got worse. I took it home and tore it apart and found the same thing you did. That is when I lost faith in shops.
 

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Discussion Starter #8
Same thing happened to my 525 after installing home made big bore kit, porting and a cam. I hav'nt had another bearing failure since the first time about 40 hrs ago but I dont ride road courses with long sweepers anymore. Ktm rebuilds are pretty easy if you buy a few tools. I have done mine several times. Good luck. Took mine to local shop for them to listen they said it was definiatly not a bearing and to keep running it till it got worse. I took it home and tore it apart and found the same thing you did. That is when I lost faith in shops.
What do you use to pull the bearing race off the crank? These is very little room for anything to grab that thing.
I too have lost faith in shops, and do all my own work now.
 

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roamer, the short answer is KTM tool 58429037037. Retails for about $75. It is a aluminum band with handles that you heat up. I also freeze the crank. Then placing this tool around bearing race transfers heat into race while you twist/pull and off it comes. (still not easy, but it does work, act quickly) Only possible from temp difference between crank and race. I have heard you can just run a bead of weld on the race and the heat will allow it to slide off. I have not personally tried that, but should work. Installing is very easy as with parts seperate, it is easy to get temp diff between crank and race. Heat race/freeze crank and it will slide right on. Be sure to press it on firmly untill it cools to be certain it is all the way seated. They like to float out a few thou of an inch. The problem is when you put the races on then measure axial clearance. If clearance is off, you must remove one race (without damaging it, welder trick is out) and change the shim behind it. Now, you have to use the tool. Unless, you are feeling lucky and shim it right on first try. Hey, it could happen. Just make sure you have too much clearance, not too little. I woud use no less than .010" and probably shoot for .015". Some say even more than that, but I think .015" is pretty good, and .020" is about all I would run. OK, pretty big window there, but you get the picture.
 

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What he said. You can get the old race off if you are careful using heat and two wood chisels as pry bars but you must be careful not to damage shim under race. Once you get the old race moving they come off easy.

roamer, the short answer is KTM tool 58429037037. Retails for about $75. It is a aluminum band with handles that you heat up. I also freeze the crank. Then placing this tool around bearing race transfers heat into race while you twist/pull and off it comes. (still not easy, but it does work, act quickly) Only possible from temp difference between crank and race. I have heard you can just run a bead of weld on the race and the heat will allow it to slide off. I have not personally tried that, but should work. Installing is very easy as with parts seperate, it is easy to get temp diff between crank and race. Heat race/freeze crank and it will slide right on. Be sure to press it on firmly untill it cools to be certain it is all the way seated. They like to float out a few thou of an inch. The problem is when you put the races on then measure axial clearance. If clearance is off, you must remove one race (without damaging it, welder trick is out) and change the shim behind it. Now, you have to use the tool. Unless, you are feeling lucky and shim it right on first try. Hey, it could happen. Just make sure you have too much clearance, not too little. I woud use no less than .010" and probably shoot for .015". Some say even more than that, but I think .015" is pretty good, and .020" is about all I would run. OK, pretty big window there, but you get the picture.
 

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Discussion Starter #11
I saw that tool in the parts book and wondered what it was.
I stopped into the local dealer this morning and they popped them off for 15 buck while I waited. Now I'm just waiting for the big brown truck. Thanks for the info.
 
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