HELP! - 1981 KZ750(E1) Starter Clutch Issues

Hey guys! Still looking for some help!

Starter clutch was slipping.

Starter itself is fine. I replaced the large starer clutch gear, as well as the rollers and springs.

Starter is still slipping. My uncle is doing his damndest to find the issue, but we've no ideas as to what to work on/replace next.

He took apart the piece where the rollers were housed in, and i've uploaded it for your review. Is there something wrong with this piece?

I've tried to inquire for access to the archives, and I haven't had a return email as of yet .

Thanks so much for your help!

Humm. Hard to imagine what the problem could be. Did you buy OEM replacement parts or aftermarket?

Yeah we're stumped. I'm almost without hope, as my uncle is an experienced japanese bike mechanic

I looked them all of my parts by their parts numbers, and most of them came from Bike Bandit, or similar things. All were new/looked good.

Hard to imagine a company staying in business selling parts that didn't actually work on bikes, though, right?

Can you bump start the bike? Might be useful to try since there could be some other more significant problem present.

Yes the bike does start. The engine is fine. Completely rebuilt during this work/job.

Its just the starter clutch.....So 0 ideas what the culprit might be?

Thanks all!

Some pics of the starter clutch gear, part #19?

Hey Scirocco!

That is indeed the gear we have replaced. Unfortunatley, I do NOT remember those grooves on it, as in the top most picture.

Is there a reasonable argument to assume that would be the culprit? How confident are you?

Thanks so much!

How have you determined which parts are actually turning and which parts are not turning?

Do you have the oil pan off so you can see gear #10 and #19 turning?

A metal to metal traction and/or form closure need a specific pressure/surface roughness to engage together. Low pressure = more roughness / High pressure = less roughness!
It is to get the right balance of both, plus the oil medium need a specific grip additive to support this.
Pics of the gear???

I passed that along to my uncle. I'm sure it will resonate with him.

Sounds like it might have to do with how "tight" we put it on there or something. We honestly barely understood how the mechanism even "grabbed" the other one....with only rollers!

I'll reach out to my uncle to see if we have those "notches" on the gear...I have a feeling we do not

I don´t know if your starter clutch gear is new or used but a little sanding can act like a miracle.
Pics be before sanding please....

If the gear is new I don't understand what could be wrong with it.

I agree with pulling the oil pan and spark plugs, and then hitting the starter while watching what happens.