barker Posted November 11, 2010 Report Share Posted November 11, 2010 My bike keeps eating flywheel keys. I just took the motor completely apart to make sure the crank was all tight, it is just like brand new. so we put in a new woodruff key and torqued everything back down. I also put a top end in because I already had it apart and my compression was a bit low anyways. Today I went to the pit and maybe 20 minutes into breaking the bike in, it starts sputtering and knocking and then stalls out. Took off the flywheel cover and the nut had backed off so much that it spun off by hand and of course the flywheel chewed up the key. Has anyone else had this problem? and how do I go about fixing this? Tomorrow im going to grab another key and try to locktite the nut on. any other suggestions?? Thanks Quote Link to comment Share on other sites More sharing options...
tripledsracing Posted November 11, 2010 Report Share Posted November 11, 2010 (edited) you need to get some lapping compound and lap the flywheel on the crank then take some red loktight on the key to the crank and then apply it to the nut and torque the nut on and you should be good to go..always worked for me.. Edited November 11, 2010 by tripledsracing Quote Link to comment Share on other sites More sharing options...
tripledsracing Posted November 11, 2010 Report Share Posted November 11, 2010 (edited) oh yea i like your avatar..lol..does me the same way Edited November 11, 2010 by tripledsracing Quote Link to comment Share on other sites More sharing options...
barker Posted November 11, 2010 Author Report Share Posted November 11, 2010 (edited) what kind of lapping compound did you use? and where might I be able to get some? haha yeah nothing gives me a chubby like a garage full of 2 stroke smoke! Edited November 11, 2010 by barker Quote Link to comment Share on other sites More sharing options...
J-Madd Posted November 11, 2010 Report Share Posted November 11, 2010 None of my motors have had that problem, but I have seen one that did exactly what you described. Start it up in the pit, and can't even get to pre stage before it dies. REPEAT x 3. I think he finally put lots of red loctite on there and torqued the hell out of it. I've heard that you can put an extra nut on there to jam it on. Quote Link to comment Share on other sites More sharing options...
tripledsracing Posted November 11, 2010 Report Share Posted November 11, 2010 what kind of lapping compound did you use? and where might I be able to get some? haha yeah nothing gives me a chubby like a garage full of 2 stroke smoke! any local shop should have it..i agree with j-madd put 2 nutts on it and that should help also..but when u go to take it bac off you will need to heat it up to break loose..good luck and i cant wait til saturday to smell some smoke myself..lol.. Quote Link to comment Share on other sites More sharing options...
fck55mph Posted November 11, 2010 Report Share Posted November 11, 2010 just FYI...DO NOT use a hardware store woodruff key...my buddy kept shearing them off on his harley...bought a hardened one from HD and it worked fine. I would make sure that you are using a hardened woodruff key Quote Link to comment Share on other sites More sharing options...
Snopczynski Posted November 12, 2010 Report Share Posted November 12, 2010 You need to lap the flywheel onto the crank with lapping compound and put an oem key back in it. Quote Link to comment Share on other sites More sharing options...
BigMatt Posted November 12, 2010 Report Share Posted November 12, 2010 I sheard a key once because I torqued the nut down and it turned out the threads were messed up on the crank from the last tard, So it read tight but was in fact loose, they were messed up just enough to wear I couldnt see it. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted November 12, 2010 Report Share Posted November 12, 2010 once you lap it, it should hold on there real good, and it shouldn't make a difference how hard, etc the key is. the key isn't supposed to have any load on it. it's just for installation allignment. at work, we put the taper seat gear on the 2cyl compressors and just a dab of blue loc-tite on the threads. zap it with an impact and call it good. there is no key, and they handle 10x the load.... i have had my flywheel come loose without loc-tite, but never made a difference between the napa key and stocker. Quote Link to comment Share on other sites More sharing options...
barker Posted November 12, 2010 Author Report Share Posted November 12, 2010 is there a certain brand or grit of lapping compound I should get? Quote Link to comment Share on other sites More sharing options...
barker Posted November 12, 2010 Author Report Share Posted November 12, 2010 also, what if I used a teflon or nylon locking nut on the flywheel? Quote Link to comment Share on other sites More sharing options...
Rotax Raptor Posted November 12, 2010 Report Share Posted November 12, 2010 Just go to the auto parts store and buy a can of valve lapping compound and work your flywheel around the crank for a while til all of the pitting or marks are gone. Make sure your threads aren't damaged. Clean it up real good, put the key in it, tap on the fly wheel by the crank with a hammer (I said tap), put lock tite on it and hit it with an impact lightly and you should be good. This happened to a buddy of mine last weekend and the fix worked perfect. Just be careful, you don't want to srew up your crank. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted November 12, 2010 Report Share Posted November 12, 2010 you don't really want to do more than laping......it will stick on there like super-glue once you tighten the nut down....and may not want to come off later, lol.........i know that it will not go anywhere if you heat it up before you put it on....not a huge amount of heat...like a couple min with your wife's' blow-dryer. you don't want to use anything but the shoulder nut. a nyloc and hard washer won't hold well. you might be able to find a shoulder pinch nut, though. Quote Link to comment Share on other sites More sharing options...
shoopie Posted November 13, 2010 Report Share Posted November 13, 2010 happened to me twice when i first got my bike running. i put a lock-washer before the nut and had a friend help me hold the flywheel tight while i cranked down on it with everything i got. hasnt come off since. i do have a question though. is it possible to shear the key without the nut backing off? would the flywheel spinning alone have enough torque to break a key? -Ryan Quote Link to comment Share on other sites More sharing options...
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