(XJ750J) Starter Clutch Noises Gone After Starter Swap

Hey all, this is my first post, it's nice to finally have something worth talking about with you. I've been lurking and reading various threads for different issues and have been able to get a lot out of the already created posts. I haven't seen anything about a starter swap reducing/resolving starter clutch issues though, so I thought I would post my thoughts and bike history.

I got the bike not too long ago, as I wanted a project bike to tinker on in the garage, as a way to be a bit more active rather than sitting at the computer all the time. So far, I'm having a lot of fun working on various issues and while it has been kind of slow going, I'm happy with my progress and also haven't been able to ride due to horrible bi-polar weather even if it was road-worthy.

When I got it, the PO said it would not always catch when you try to start it, and sold me the bike with a newly rebuilt starter, a full spare engine (in questionable shape, at worst it will be a good practice engine to tear down and rebuild without the possibility of ruining a running engine), and a "brand new battery". The battery was dead and unable to be saved, so I had to get a new one. When I put the rebuilt starter on it, it was spinning backwards and freewheeling instead of cranking the engine. Once I swapped the new starter with the old one he also gave me, it cranked but definitely had the "box of rocks" starter clutch noise and wouldn't always crank, like he said.

After running a can of carb cleaner through my carbs based on advice from my dad (because cylinder 1 and 3 were running colder than 2 and 4), I decided I should go ahead and pull and clean my carbs. My bike apparently didn't get the memo that the carb pull was supposed to be hard, because the rack came out quite easily. The bike had sat for a year with the same gas in it, and the PO didn't drain the carbs so there was definitely some varnish. I was told I could use acetone to dissolve the varnish and it seems to have done a good job. I put the carbs back in, it ran with a lot of white smoke, but the bike no longer chugged when I twisted the throttle so the carb clean seems to have gone well. Next on my list is checking my valve clearances. It's been done at some point in the past, since there is a nice oozed orange seal around the cover, but who knows how long ago that was.

I got around to checking out the rebuilt starter tonight and it turns out the rebuilder used the wrong brush plate, causing the stator to rotate the wrong way. I was able to make a working starter between the old one (took the plate and brush cover) and the new one (put new brushes in old plate, used all other new parts but the insulator plate, which was in pieces somehow). After installation, the start clutch noises seem to be gone, at least for as long as I cranked it. It's about 25 degrees here right now, so the cold blooded 750 doesn't want to start, but it cranked with no issues.

Could it be possible that the old, worn out starter was not able to crank fast enough or with enough torque to properly engage the starter clutch? Or is that wishful thinking and me dreading a full engine teardown to find a broken starter clutch?

 

Yes.
Typically we recommend that people make certain that the electrics are working properly before diagnosing the starter clutch as being faulty.
Your other starter motor can be rebrushed (by you) to function like new.
Replacing your starter motor brushes w/ pics

 

The po had the brush plate clocked wrong if it was spinning backwards ( even I did that once) the starter clutch slipping effected all the manufacturers of jap bikes to varying degrees on the 4 cylinders ...Suzuki had a better design that could be replaced without major surgery. My 750 does this when engine gets hot , and I rebuilt the starter and went to 20w50 oil it helped . There are some threads on splitting the case and replacing the starter clutch on the forum and go to top of page to xj4ever the information overload hour. At some point I will have to tear down my engine to do the deed on mine , I recently bought another engine either to swap in or rebuild have not had a chance since winter won't let go and unheated garage conspire against me.

 

I'm pretty happy to hear that, because while I have a desire to learn more about bike mechanic work, a full engine teardown is definitely above my paygrade for now. The issue was that the rebuilt starter plate was not the right one, so the brushes were rotated 90 degrees and Positive and Negative were backwards as a result. I've kept the spare parts worth keeping from the unused parts. Thanks for the reply!

 

It was actually the wrong brush plate altogether, and had no way to sit in the correct orientation. If I start having more starter clutch issues, I might try moving to a heavier oil since you said that. A case split is something I'll have to gain some more confidence (and tools!) to be able to do properly, but I know exactly what you are talking about with an unheated garage - I actually have 2 space heaters trying to bring up the temperature today so I can try to start the bike and do some more checking after my carb clean