Maintenance & Technical > KX500 Original

Flywheel keys

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RoostDaddy:
Right key, no flywheel weight. 
Maybe the first time it just wasnt lapped enough.  Hopefully it is this time.
I just wasnt too sure if there was something else other than them not being mated together.  But this seems to be the verdict by all.
Thanks for the input!

kaw rider:
recommend new nut thats not gail up and torque down to manual spec.

Polar-Bus:

--- Quote from: RoostDaddy on May 17, 2009, 01:22:19 AM ---A buddy of mine has sheared 2 flywheel keys within the last 2 months on his K5.  I told him to clean the pieces out of the flywheel and off the crank.  Then use a piece of emory cloth (lightly) just to make sure everythings smooth.  A dab of valve grinding compound and mate the flywheel and crank.
 
If this continues does anyone have a better suggestion? 
And what would cause it to shear the keys?  My thought was too much timing, but it was set @ stock.

--- End quote ---

I work a lot with tapered fits and keyways on industrial fluid pump shafts, and I can share what i've learned. If you have experienced a sheared key, that means that counter-rotational forces from the flywheel was hammering the key, which in turn was hammering the primary output crank taper keyway slot. My thinking is that there is a slightly "raised" area parallel to the slot on the crank taper, and this is causing the flywheel to have a less that ideal fit. I would try to carefully file down the area all around the keyway slot. Also make sure the key has a clean, and snug fit within the crank keyway. It's hard to pinpoint this issue without actually running a dial indicator around the area of the keyway, but it's a thought... good luck, hope you get it squared away!

hughes:
Crank tapers and the flywheel inner hub is an interference fit. It's mechanically locking tapers. The flywheel key is just a locator for the flywheel. The flywheel nut when torque presses the two tapers together. It's very important that the inner hub of the flywheel and the crank tapers are cleaned with contact cleaner before install. Once the flywheel is installed correctly you could remove the flywheel nut and run the bike with no issues (not recommended).

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