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H series 220. Bike died on me, luckily I was less than 100 yards from the truck!

Woodruff key is sheered. Crank looks ok since I shut the bike off right away (well, it basically died.) I’ll be able to clean up the swarf easily. The flywheel MAY clean up on my lathe.

Looking at the flywheel, the rivets that hold the inner section to the outer weighted part, are loose. As in, the flywheel is able to rotate a couple degrees fore and aft relative to the part held to the crank with the nut.

Can I replace those rivets? TIG Weld the inner to the outer maybe? Or should I be shopping for a new flywheel?

Haven’t heard of this happening before. Has anyone else run into this? Thanks fellas!

I'd buy a new flywheel. Welding with magnets close by can create some challenges. It can be done, but it can make the arc wonder around sometimes making it more of a challenge.

Molly's 70 wrote: 01:52 pm Apr 07 2021 I'd buy a new flywheel. Welding with magnets close by can create some challenges. It can be done, but it can make the arc wonder around sometimes making it more of a challenge.

Good point. First step I'm going to drill those rivets out and see if I can clean up that inner bore on the lathe. If it will, might be able to machine some new rivets for the two sections and press them together.

What material would you use to machine new rivets?

Got the two parts of the flywheel apart. Luckily all the wear was limited to the rivets themselves, both sets of holes are still round and true. Old rivets measure 0.250” at the base (which isn’t worn) so I’ll look for some press-type rivets tomorrow. I was able to get the crankshaft cleaned up nicely as well as the flywheel bore. Picked up 3 woodruff keys from the dealer as well.

As a final step, I’m going to use some lapping compound and lap the flywheel taper and the crankshaft together to each other for an even more perfect fit.

Wow. Good luck with it. That is not a common failure at all!

KDXGarage wrote: 06:24 pm Apr 07 2021 Wow. Good luck with it. That is not a common failure at all!

I was pretty surprised! Especially with how anal I am about torquing everything to spec (I even paint mark the bolts after!) I’m sure it was torqued. I suspect the flywheel rivets being worn led to this.

Yes, I know I can throw a new (used) flywheel on, but I like machining things and what’s saying it wouldn’t do the same thing eventually? I’ll take this opportunity to upgrade.

Was the woodruff key that sheared factory Kawasaki? or a hardware store version?

I don’t do generic “hardware store” parts. It was genuine.

Definitely an odd failure. I've never hear of the '89+ bikes having flywheel failures other than the woodruff key. Please let us know what you do to fix it.

Side note, I see you're still running your homemade high output stator. Still got mine as well but haven't installed it. Might try some night riding this summer so I need to finally get it done. Thanks again for your excellent thread on how to do it! I know it encouraged a lot of KDX owners to do the same.

Haha yep! That’s still the original one going strong!

Bike got a complete rebuild 2 years ago and has only had 2.2 hours put on it since... Didn’t get to ride at all for close to 18 months but she’s minty! I’ll do a rebuild thread one of these days I have about 500+ pics! Even replated all of the hardware!

Nice!

Damn, Nick, she is way too pretty to ride now! Most excellent!

Thanks fellas! I didn't get much time to ride last year so it sat under a cover for about 18 months! SS, I was so busy ferrying my airline's planes down to Pinal last year (your neck of the woods!) due to COVID that I had no time to ride!

Back on topic, I'm going to source some rivets for the flywheel today and press them in, I have a solid rivet mandrel somewhere around here... Once that's done I'll lap it onto the crankshaft for good measure, install a new KAWASAKI flywheel key, and loctite the nut for good measure once it's torqued.

Keep us posted! BTW, my main riding areas is only a few miles from Pinal Air Park. You gotta sneak your bike in there some time and we'll meet up and ride!

I have read more than one person over the years on the internet (not here exactly) that used a hardware store woodruff key. I wondered about it, but didn't ask. I am glad to hear you had a "real one" in there.

Alright fellas, got the new rivets. For anyone who needs the info, they’re just a standard 1/4” solid rivet.

I used a diamond grit lapping compound to lap the flywheel taper to the crankshaft. Used my flywheel puller to hold it. Oh man what a job it did! After everything was clean, I was able to grab that flywheel center with my hand and turn the bike over using the taper alone. No woodruff key, no nut. Holds like it’s supposed to.
After that, I couldn’t just put the old flywheel back on, so I decided to bead blast it, and then electroplate it and the hardware. The center got blue chromate, the flywheel and hardware got yellow chromate after the zinc plating.
Tomorrow once everything is set up, I’ll press the two halves back together with new rivets, install the flywheel, and give’er.

More pics of the electroplating.

WOW!!

You always go the extra mile. Looks awesome!