Breaking flywheel keys

[92f150300six]

Ok when I bought this blaster it had a broken flywheel key. So I bought a new one. Rode the quad about 3 times maybe 10mins each and now I have another broken key. What gives the slot both in crank and flywheel look perfect. The taper on the crank looks good the taper in the flywheel is scratched pretty good now. Not sure why it's doing it or why.Any help would be great.

 

[Blaaster]

You may need to lap the flywheel.

Lapping the flywheel consists of putting some fine valve grinding paste on the taper of the crankshaft, placing the flywheel on, ( without the key), and revolving the flywheel back and forth.

When the flywheel turns more freely as the paste gets broken up, take off the flywheel, wipe out the used paste and inspect.

The grooves should now be flattened out.

If there are still grooves, repeat the operation until good mating surfaces are made.

Be sure to wash off all, and I mean all of the grinding paste.

I like to finalise by using a Duco cutting compound No 3 for the final lap.

Tension the nut to 53 ft lbs, some use Loctite but I never do, it is not the nut that holds it on, it is the pressure applied to the tapers.

 

[scotj77]

go to an auto parts store and get you some valve grinding compound. put some on the crank then slide the flywheel on without a key. work the flywheel back and forth over and over until when you clean the two surfaces off they both look to be completely sanded to fit each other. the actual contact from the flywheel to the crank shaft is what holds the flywheel still. the key is mainly for timing.

make sure you have the flywheel all the way on when you bolt it down. you do have the spacer behind the nut when you torque it down right?

 

[92f150300six]

Spacer is behind the nut. And I'll be honest I smacked the nut on with my impact. Never thought about lapping the flywheel make sense . Plus I already have some grinding compound so that makes this that much Easyer.now I'm guessing like on vavles I should work corse to fine on the compound?

 

[dksix]

Yes, course to fine. Like said before, it's the taper that locks the flywheel to the crank, the key is just for alignment. When you install the flywheel you want everything clean and dry, any form of lube impedes the taper lock.

 

[92f150300six]

Yeah the Jacobs taper holds it in place just as it does on a tierod. Maybe this weekend I'll get to work on it.

 

[Blaaster]

Spacer is behind the nut. And I'll be honest I smacked the nut on with my impact. Never thought about lapping the flywheel make sense . Plus I already have some grinding compound so that makes this that much Easyer.now I'm guessing like on vavles I should work corse to fine on the compound?

If you have smacked the nut on with an impact, it may pay to see if the threads are not stretched.

I always use a No 3 cutting compound for the final lap.

 

[92f150300six]

If you have smacked the nut on with an impact, it may pay to see if the threads are not stretched.

I always use a No 3 cutting compound for the final lap.

I'm willing to bet that is exactly what I've done. I was in a rush and the gun was right there. Knew I shouldn't but did it anyways. You know the old saying don't have enough time to do it right but I have enough time to do it twice. Lol I'll check it out better tomorrow.

 

[92f150300six]

Well so far so good. Haven't got to ride it much but I did successfully run it out of gas and that was just awesome lol. I want to say thanks for all that helped.