Kickstart Shaft Snapping

Got an issue that I can not seem to figure out and hopefully one of you can sort me out.

I have had 2 kick start shafts snap in half on the first kick attempt after putting them in.

I am at a loss to figure out what I could possibly be doing wrong when I re-assemble the inner and outer gearbox. Everything fits perfect, the outer cover bolts in perfect, the pawl on the shaft is perfectly aligned in the gear and the shaft pokes out of the outer cover perfectly and allows the kickstart assembly to perfectly fit on.

I test the shaft and assembly first using the clutch to allow for free movement to ensure it turns, then I do it by hand under compression to ensure it will pull proper and as soon as I kick it, it snaps.

As soon as I kick it over, it snaps and the assembly still is attached to the now broken shaft and of course, it swings down with the peddle now below the pipes.

I can not figure out how with all covers and parts fitting perfect, this could be happening for the second time. Is there something I am missing?

Any suggestions would be appreciated.

I had a similar problem. Norvil sent a visually perfect shaft that broke immediately. I sent photos and they replaced it fast without trouble.

The problem is the manufacturing of the shaft. The bushing should be top-hat shaped. If the bushing is straight on the OD, the shaft wall thickness is too thin, and becoms brittle after case hardening.

If you have straight bushings, your shafts are junk, and the vendor should replace them. The manufacturer bored his shafts oversized, and made straight bushings to compensate. They break.

Buy the shaft and bushing separately and press the bushing in yourself.
A reputable shop should replace your bunk shafts for free. Take the parts manual to prove how they should look.

Good luck.

oh my, you would not have a good picture of a good one would you?

Sorry. I don't have a photo. The parts manual and and service manual both have fairly clear exploded views that show both the shaft and the stepped, top-hat shaped, bronze bushing.

You cannot tell if the shaft is correct unless the bushing is removed, or the shaft is broken. If your broken shafts have internal bushings that are NOT top-hat shaped, you have received a defective shaft assy. If the bushings are top-hat shaped with a fairly thin stepped wall section, there is some other problem.

Does this help?

super advice as usual from this forum, since I have two broken now I will examine both.

Thanks again. I will discuss it with my parts provider....

Resolution on this:

The Kickstart shafts were brittle and machined slightly off tolerance levels. The good folks at Motoparts Inc. in Edmonton found a non brittle one and machined it down to fit on the layshaft and the bike is now back on the road.

Dian said:

Resolution on this:

The Kickstart shafts were brittle and machined slightly off tolerance levels. The good folks at Motoparts Inc. in Edmonton found a non brittle one and machined it down to fit on the layshaft and the bike is now back on the road.

Click to expand...

I bought my MKIII from those guys. They (John) seemed like an alright bunch.