Repeatedly shearing flywheel key

[martyestes]

Hey y'all.  First time lurker here.  I've been rebuilding a '96 K5, and it just came back from a mechanic who replaced the crank bearings, seals, etc. Low hour bike, but was drinking trans fluid at a rapid rate and smoking like crazy!  Since it came back, on initial start-up, ran for about 1-2 seconds, then died.  Then really strange backfires, kickbacks, but wouldn't start.  Searching here - figured it was woodruff.  Correct.  Replaced it.  And the EXACT same thing happened. Two things at work here:  Bottom end work and I also installed a Steahly flywheel weight.  Pretty sure I installed it correctly...but dunno. Not sure if the timing is radically off BEFORE I started it both times, or only after the key sheared.  Looking at the stator vs. pictures of other bikes, etc...it isn't radically off visibly. 

Possible my guy installed a flywheel off another bike or is there a way to do the crank wrong and have it be off?  Any ideas?

Thanks, I'm scratching my head here.  And yes - I searched first!   

[kxpegger]

I'm just guessing but either the key slots are out of spec or it's a poor quality key. You may be able to find an oversize key and file it down for a nice snug fit?

[Motorrad]

I'm just guessing but either the key slots are out of spec or it's a poor quality key. You may be able to find an oversize key and file it down for a nice snug fit?

flywheel key doesnt hold on the flywheel.. the taper does...     Keyway is just for alignment.


Lap your flywheel to your crank..  Valve lapping compound works great.

[martyestes]

Thanks.  I have been searching all over and think that I probably did not have the assembly on secure enough.  Both times.  I will try once more, then break out the lapping compound.  Thanks for the replies.

[alward25]

Torque is key, it must be torqued to spec.  Use oem keys too, one that looks good enough will not be.

[mxaniac]

If it is a tapered shaft then the key is for alignment only.  As mentioned it needs lapped and properly torqued.

[kxpegger]

I'm just guessing but either the key slots are out of spec or it's a poor quality key. You may be able to find an oversize key and file it down for a nice snug fit?

flywheel key doesnt hold on the flywheel.. the taper does...     Keyway is just for alignment.


Lap your flywheel to your crank..  Valve lapping compound works great.

No more just guessing posts from me! Lol!

[martyestes]

Just an update.  I gave up on the Steahly weight, carefully cleaned the end of the crank and inside of the flywheel and added about 10% extra torque with the torque wrench.  Viola - it worked.