Starter clutch(?) Sticking

Friends ;
Perhaps someone can help me with some advice...
I have a 1981 Yamaha XJ650.
The engine is not original,I believe it is off of a SECA,perhaps. The reason I say this is because the shifting lever is a cantilever contraption,and my original engine had a solid shift arm with no linkage.
Anyhow...
The problem is a bit hard to describe but here goes..
The starter motor engages,cranks the motor and it starts. Sometimes,something sticks,does not release,etc.
The starter motor doesnt keep cranking,that stops. However,there is an unusual noise by the starter that won't stop- unless I get the bike up to speed,stop the engine,and while still rolling dump the clutch and 'bump-start' it.
When I turn off the motor while coasting,I can hear something release inside. This does not always happen,but it worries me.
Any ideas ?

 

When was last time oil was changed ? You might try some sea foam in the crank case , ride till engine is hot , then drain oil , I recommend refilling with Shell Rotella 15/w40 . See if it makes any difference. I have the opposite when my engine gets hot the starter clutch slips . I have a spare engine when it gets bad enough ,I will swap it out and do the deed of splitting the case and fixing the starter clutch.

 

Thanks so much for a reply! It is funny you say sea foam,I just saw a Scotty Kilmer video and he spoke pretty badly about sea foam,but mostly about it messing up catalytic converters...
I JUST changed the oil a few hundred miles ago. I don't ride much so that does not help either I am sure.
If the purpose of the sea foam is to clean sludge out of the engine,I could just make a mix of kerosene and oil and idle the engine with that in it for 10 mins and drain,then put in fresh oil and filter. (I've cleaned dozens of car engines like that)
Let me ask you something else. I am fuzzy on this but are there actually 2 oil drain plugs on these engines? I think I read that but I never found the second oil plug. It was supposed to be lower than the front drain? Maybe you know?
What could happen,can the clutch or chain break and wreck the engine? Is this a warning that it may break big-time? It has to be the clutch contraption,or could
it somehow be the starter motor? (Perhaps I will 'borrow' the starter off of my XJ700X and see if it acts differently)
Thanks for any help or advice!
Ronald

 

There is a drain for gear box ...DO NOT TOUCH IT . Yes the seafoam will help break up deposits. I to have used diesel in the the crank case , no sure what this might do to the clutch plates is only concern. DO NOT use synthetic oil as this can cause starter clutch slippage possibly . If yours is dragging it is possible you have build up and springs and roller are hanging up. After you change oil ,ride at least 25 miles combination low speed as well as high speed 55-70 , pull over shut down , and try restarting see if symptoms change. .

 

I appreciate your reply. I am pretty good about changing the oil,in other words I think it is unlikely that the engine is dirty at all,let alone dirty enough to gum things up-but what the heck,flushing the crankcase,giving the engine a good rinse is never a bad idea. (if you use the right stuff...)
Thanks for the heads-up on the second oil plug,I will forget all about finding it!
I joined this site in 2013 but was never able to actually log in and use it from my phones for some reason. I tried many times over the years,with different phones as I updated them. I finally gave up until recently,and BINGO! I'm finally in!
I took the long way.
You have a good day,new Friend !
Ronald

 

the starter clutch (sprag bearing) is directly connected to the starter on one side and the crank on the other. if it were to jam the starter would spin really damm fast when the engine gets to 5k rpm.
i doubt it would last a few miles.

how do we know that?
try disconnecting either small wire in the solenoid and jump the two large terminals to start it,see if it still acts the same.
or don't use the kill switch, just stall it with the clutch in the driveway, see if the starter is still running
i think your solenoid is sticking

 

Thank You. I will get a new starter solenoid.

 

Friend;
The sticking starter was indeed an electrical problem,not a mechanical problem.
Suffice to say that there was some sort of backfeed to or through the solenoid.
I changed the wiring and have had no trouble since. Thank You for pointing me in the right direction !
Ronald