Confirm my suspicion - dying starter motor

Topper wrote: Apologies for the bump. I'd really like to take care of this today or tomorrow. Hoping someone can advise me on whether or not roughing up the race on the starter clutch gear with sandpaper or a file is a really bad idea or not.

I don’t think filing or roughing it up would be a good cure. If you cannot find a NOS one you may be better off taking it to a machinist and having him turn it (but not remove hardly any metal) to smooth out any irregularities in the surface. He may be able to impart a finish similar to the original. The original finish has very light machining marks about 120th inch apart. The first picture below shows a NOS KZ650 starter gear – you can see the finish I mentioned (the surface is 7/16” wide). The second picture shows a used KZ650 starter gear that was causing the ooooga horn sound they can make when they need replacing. Maybe show the first picture to a machinist and see what he says he can do to match it. Ed

Ed, that's really helpful. Mine definitely looks more like the second picture.

Time for disassembly (again) and some pictures.

Motor Head, I'm watching those ebay auctions already! There's just no way to know if they're any better than what I've got.

Z1 doesn't have and can't get the starter gear. Ron Ayers lists one on their site, it's about $200 shipped. I may call them and make sure they really have it.

Any ideas what having my starter gear machined is likely to cost? I've never had any work like that done.

Cost would vary greatly. Maybe 30-100, depending on the shop. Some of the members here could do it for you, but then you would have to Mail it back and forth. I wouldn't take off very much on the gear journal. It will make the rollers be even father down the groove with Less Spring Pressure.

Ronayers is a very good place to buy "Active" Kawasaki parts, and I have bought from them at least 6 or more times. However, my experience has been if the part is no longer available they won't have it even though they list a price for everything. Ed

Disassembled and reassembled the starter clutch again and this time I've had moderate success. I've had several successful starts now but I did hear the starter clutch slip once. So I won't say it's 100% fixed and I'll be adding a NOS starter clutch gear to my parts wish list.

I did a couple things differently this time around that I think made the difference. First here's a picture of the clutch on the starter clutch gear.

Motor Head asked about where the rollers were riding. Do they look about right?

Here's the journal (is that the right word?) on the starter clutch gear.

This looks pretty worn compared to what Ed showed of the original new part. I'm going to look for a NOS part. If this all fails again before I find one, then I'll try taking the gear to a machine shop to have it resurfaced more like the original.

Last photo, here's the underside of my rotor.

See all that wear from the rollers? That was something I couldn't see before because I couldn't get the starter clutch off the rotor. A little persistance with a rubber mallet and I finally got it loose.

I took some emory paper to the back of the rotor and really tried to smooth out that wear. There were definite ridges I could feel with my finger and I think those could have interfered with the rollers and kept them from grabbing.

I took the same emory paper and tried to rough up the journal on the starter clutch gear. It didn't really look like it did any good, though it might have provided a little more friction for the rollers to grab.

I liberally cleaned everything with brake parts cleaner, put it all back together and it seems to be working.

The starter clutch mechanism was a bit of a mystery to me before I did this, so I made a video to help anyone who may be similarly confused about how they work.



As always, many thanks for all the help. I hope this has done the trick at least for the time being.

It looks to me the rollers are setting a little "High", rubbing where they shouldn't. Is there any deposits in the roller pockets preventing them from sitting deeper? Also what type/kind of engine oil being used?

You've probably read this before:

JASO OIL SPECS:
Find an oil that shows the JASO-MA rating on the bottle; there are plenty of them available both dino and synthetic.

The ingredients in oils have changed over the years. For example, today's Castrol GTX oil (and pretty much all other AUTOMOBILE oil) is not the same as it was in the 1980's. Back then it worked great in KZ bikes. But, things have changed. Early AUTOMOBILE oils contained zinc phosphorus compounds (ZDDP) to protect engines from metal to metal contact. This was good for engines, but it was found to be destructive to catalytic converters. Consequently, in AUTOMOBILE oils ZDDP was virtually eliminated and replaced with different chemistry generically referred to as "Friction Modifiers."

These work fine and offer good protection for normal AUTOMOBILE engines. However, today's AUTOMOBILE oil "Friction Modifiers" are destructive to wet clutches. KZ bikes (and many other brands) have wet clutches. As a result of these oil chemistry changes a distinction needed to be made between those oils which are suitable for wet clutches and those which are not.

That distinction was documented by the Japanese Engine Oil Standards Implementation Panel (JASO). JASO developed a number of different oil specifications for different applications. The specifications that apply to 4 stroke motorcycles fall under the "4T Specifications." Within the 4T specifications the JASO MA class oils are specifically formulated for 4 stroke motorcycles with wet clutches.

Using oils that are not designated as meeting the JASO-MA standard may be destructive to KZ clutches. Here's a link that may be helpful:

www.oilspecifications.org/jaso.php

Topper,
It looks to me as the Rotor is worn, the rollers will bind against the worn areas of that rotor. The rest actually looks fine as far as I can see from the picture. I think the rollers end up bound up on that worn surface of the rotor. Then they can not apply the force down onto the Gear Journal. I think I would replace the rotor. Check and see if those rollers have lateral movement at the worn spots on the rotor/ side to side movement.

Motor Head, thanks for confirming my suspicion about the wear on the rotor. That photo is the "before" shot. I was able to sand out the high spots pretty easily. I'm not sure it's a permanent fix, but fortunately good rotors/flywheels are a lot easier to source than the starter clutch gear.

From looking at the starter clutch on the gear, you think I'm OK there? The rollers are positioned about half way in their grooves. If they cross the halfway point and get on the down slope of the gear journal will it still work?

Topper, I think the rest looks pretty good, rollers in the halfway position should be fine. I think the problem lies with the worn area on the rotor.

Thanks again for all the help. That's one issue resolved, just a couple more things to do and I'll be in good shape for some spring riding!

so I have the same issue, as it sits on the bike there is looks like there is wear on the front and back but it is not able to be perceived by my finger, however on the top or bottom where the roller sits with gravity there is perceivable wear, its not terrible wear just barely noticeable grooves, do I need a new rotor or can I just use new stronger springs and attempt to sand the grooves out with fine grit sand paper. Or do I need a new rotor just because of the damn grooves?

and sorry I don't mean to steal your thread, but we frown upon unnecessary new threads.