XJ750 clutch/starter/engine issues

Hey all,

Been lurking the forum for a bit and getting most of my questions answered based on searches, however I've come up against something that I can't quite seen to find an answer to.

First off, a little rundown... I've got a 1983 Maxim XJ750. PO pulled the carbs and exhaust and left it sitting for about 2 years before I bought it. I subsequently left it sitting for about 5 years before I started trying to get it back on the road due to these gas prices.

The clutch was sticking, so I rebuilt that. I've just pulled the starter to rebuild that, but I'm waiting on the kit to complete it. Most everything is back together aside from that starter, but I'm finding that my clutch is still stuck. Also, I'm unable to turn the engine by hand even thought I've observed the pistons moving, so I know it's free.

Before I pulled the starter, I would hit the switch, get a satisfying click from the solenoid, but nothing else. I hear the starter spooling down after I release the button, so the starter is engaging but not cranking the engine.

I'm a little confused about what's going on. The engine is free but can't be turned by hand, and admittedly the starter was most likely an issue because when I pulled it apart it was just filled with carbon and the commutators were pitch black, but I still don't understand the cranking issue.

Could there be an issue in the transmission? I kind of doubt this because when the wheels spin in gear, it drives the crank and the pistons. Any ideas?

 

are you sure the starter is spinning the right way, they can run the wrong way if the components are'nt assembled correctly.?
what do you mean by ,the engine cant be turned by hand, how are you trying to turn it?

 

I've got the left hand side cover off and trying to turn the square nut with a 19mm wrench. Gives about 1/8" in both directions, but that's it.

 

Assuming it is in neutral and spark plugs removed?

 

I'm no Yamaha Certified Mechanic, but that can't be good.

 

Doesn't make sense if the crank will turn with the rear wheel while in gear.

 

What about the starter alternator Hi Vo chain guide breaking up? Are their any black plastic bits in the engine oil? Have you removed the cam cover to make sure nothing is wrong with the top end of the engine, cam chain etc?

 

Correct, in neutral with plugs out. I have not taken the cam cover off yet, and no plastic bits in the oil.

I'll not be able to get back to it for a couple days, but I'll take that cam cover off and take a look inside.

 

It may be worth it to mention that I did a complete, ground up wiring harness, as the PO had hacked it to the point of being completely unserviceable. I eliminated all safety switches, only keeping the low oil switch in place. Did I eliminate something that is completely necessary for this bike to start?

 

Why did you remove the safety circuits? If you understand how they work, you should have left them in, since they do make the bike safer. If you took them out because you don't understand how they work, then you may have removed something that is necessary for the bike to start or run.

However, I don't understand how several of the things you said can all be true. You said you can't turn the crank with a wrench on the timing nut, but you can see the pistons moving. Those two don't seem to go together.

You also said the starter is now spinning when you press the starter button, but the crank doesn't move? Is that correct? If so, reversed starter rotation, as mentioned, or maybe the starter clutch is shot. Or maybe something with the primary chain, but then I couldn't see the pistons moving... at least not much.

Overall, I think not being able to crank the engine around by the square nut, while in neutral, is a bad sign. Maybe there's something broken or jammed in the clutch basket that also explains the "sticking" clutch...

 

So update... Clutch was rebuilt and is now moving freely. I rebuilt the starter and installed it. I followed several tutorials, so I'm confident it's operating correctly. Still only a loud click when the starter button is pressed. Before it was rebuilt, I would hear a click from what I believed was the solenoid, but nothing else until I released the starter button, then I would hear a slight whining from the starter motor, like it was winding down. The same can be said after the rebuilt, although the click is more definitely coming from the starter motor than the solenoid and the same slight whining/winding down coming from starter after button is released. It sounds like it's trying to engage the starter clutch but is unable to move it.My thoughts were the starter clutch was shot but I haven't had opportunity to try and bump start it yet to see if I can at least start it and have it run that way.

Still unable to turn the crank by square nut.

I removed the safety circuits because I don't feel the need for a side stand relay and all the other various but ultimately not very useful switches that prevent the bike from starting, especially if I was going to have to completely rebuild a wiring harness. The only possible thing that I could think that would be absolutely necessary for the bike to run would be the neutral switch. Thoughts?

 

My main thought is still that being unable to turn the engine by the square nut is a big red flag.

 

Me too. That doesn't smell right.

 

I hope you don't have a dropped valve. Crank not turning with a wrench on the end of the crankshaft it not a good indication. I have never seen an XJ with a dropped valve to date.

 

didnt you try the starter motor after you rebuilt it, before fitting it, ?
by hooking it up to a battery, ==negative lead on the motor casing, positive lead on the large motor terminal.
that would prove one way or another, if your rebuild was correct, before you delve into solenoids, starter clutches, etc