XS750 question, starter not engaging neutral

[cbarter]

Hi, hoping the cross knowledge here is applicable to the 750s, or just general understanding and troubleshooting. This bike has been running for the 3 years I've owned it, seems like something has quit and I need to repair it. 79 XS750S

Started the bike with the electric starter, was running, then cut out with a small sound. Now the starter just free spins, not engaging in neutral to crank the bike. The kick turns the pistons a bit, but not firing, seems weak... If I put it in 1st or 2nd the starter and the kick both engage and move the bike forward. The sound of the starter in neutral has no clicking or clunking, just free spinning. I am having trouble finding the information to learn about how the transmission assembles and works to think this through. My inclination is something is wrong with however the trans cranks in neutral as the starter is engaging in gear. I don't know if this is something to do with a stuck starter clutch that lead to some other damage. I am probably going to go take off the crank cover before waiting for a response here but I'd really appreciate any insight or direction to information regarding how the transmission is designed.

The real thing here pushing me away from what I've read online about the starter clutch and or battery, is that it was running fine until an acute moment where something quit, but also that when in gear there is power through the drive train.

Thanks in advance,
Appreciate it.

 

[Bruno_c]

Hi, hoping the cross knowledge here is applicable to the 750s, or just general understanding and troubleshooting. This bike has been running for the 3 years I've owned it, seems like something has quit and I need to repair it. 79 XS750S

Started the bike with the electric starter, was running, then cut out with a small sound. Now the starter just free spins, not engaging in neutral to crank the bike. The kick turns the pistons a bit, but not firing, seems weak... If I put it in 1st or 2nd the starter and the kick both engage and move the bike forward. The sound of the starter in neutral has no clicking or clunking, just free spinning. I am having trouble finding the information to learn about how the transmission assembles and works to think this through. My inclination is something is wrong with however the trans cranks in neutral as the starter is engaging in gear. I don't know if this is something to do with a stuck starter clutch that lead to some other damage. I am probably going to go take off the crank cover before waiting for a response here but I'd really appreciate any insight or direction to information regarding how the transmission is designed.

The real thing here pushing me away from what I've read online about the starter clutch and or battery, is that it was running fine until an acute moment where something quit, but also that when in gear there is power through the drive train.

Thanks in advance,
Appreciate it.

Maybe a broken timing chain?

 

[jpdevol]

I don't know if this is something to do with a stuck starter clutch that lead to some other damage. I am probably going to go take off the crank cover before waiting for a response here but I'd really appreciate any insight or direction to information regarding how the transmission is designed.

I'm not very experienced with the 750, but I'll try to help.....
There's an idler gear and a sprag clutch in there (after the start motor) that may have issues

 

[cbarter]

Maybe a broken timing chain?

It was indeed a broken timing chain. Just came to post the update. Thanks for the thought! You were spot on.

Any advice on that job let me know.

Thanks!

 

[Bruno_c]

I think you will have to remove the complete top end to pick up the broken chain fallen in the bottom of the crankcase.
Maybe you will find also damaged valves.