Having issues with starting while at operating temp

(I believe the bike is a ‘82 xj750) The issue I’m having, is when I got to start it up on a cold start, she fires right up after maybe 2 or 3 cranks and sounds great. She’s rides extremely well and has no issues. But after I’ve ridden a while and I shut it off, if I go to start it while it’s hot then the stater sounds super crunchy like it’s not making full contact. It’s sounds like it’s catching for a half second, then is super crunchy. I’ve tried this with 2 known good starters and known good batteries. After I let it sit over night (or let it cool completely) the issues disappears and the bike fires right up. Any advice is helpful

 

That noise is the starter clutch failing to engage. Common problem. Gets worse with time and heat.

Start here:
https://www.xjbikes.com/forums/thre...building-your-slipping-starter-clutch.130438/

Unfortunately, reviving the starter clutch is no small task - at a minimum you need to pull the engine and split the cases to get to the starter clutch. Once you go that far there is a lot of other "while you're in there" things you could do.

I just rebuilt one over the winter and installed new springs in the starter clutch. Haven't had it out a hot day yet (have had no hot days yet), but so far so good. Here is my story:
https://www.xjbikes.com/forums/threads/shell-rotella-t6-15w-40-synthetic-oil-experiment.132471/

 

I read the thread about the other things it MAY be. I haven’t noticed any drive clutch slipping at all. I can probably give the Seagram treatment a go and see what that does. But if all else fails, do you happen to have a link to a thread that takes me through the steps of splitting the case and replacing the old starter clutch?

 

Yes, @Jetfixer did a thread on it: https://www.xjbikes.com/forums/threads/dreaded-starter-clutch-replacement.130190/

Also, get a Haynes manual (or similar).

While you're in there, you will 100% want to replace the primary chain guide.

Then you have to decide how far you want to go and what your budget is - personally, if I'm getting that far into it I would at least want to hone the cylinders and lap the valves. All the gaskets and o-rings and stuff isn't free, so you need to budget for it.

 

The downside to the Seagrram treatment is that you can get over the legal BAC limit quickly........

Using Seafoam is a lot less risky.

 

what oil are you using in the engine? , is it motorcycle oil?, and is it the correct viscosity.
not using the correct oil could produce the symptoms you have, before you go tearing into the engine, if you dont know whats in there, flush it out and refill with correct oil

 

Hey all quick update. I went to see what oil I was using and sure enough, it was some full synthetic stuff that I’ve read is no good for these bikes. So I quickly drained the oil, replaced the filter, and went and got me some rotella t4 15w40. I let it drain over night and refilled this morning. I put just about 2 cap fills of Seafoam in along with the oil. On the first button press I got the can of rocks, but on the second it fired up with is pretty typical. I let it warm up for about 10 minutes or so and went on a ~10 mile ride. I immediately noticed my clutch is MUCH more responsive almost as if just a sudden boost of torque compared to how it was, and it seemed to run better over all. I got back, shut it off for a just a minute and held my breath to press the start button again. To my surprise, absolutely zero can of rocks sounds. She fired up so nicely. I’ve ridden one additional time since then with no issues. If anything changes I’ll update but for right now it seems the issue is resolved. I’ll run the seafoam a little longer and then do a fresh oil change. But so far I’m very pleased with the results.

 

That’s great news. I wouldn’t run it too long without changing it again- oil is cheap, engines (and labor) are expensive