Yesterday I went out to start my connie and it turned over one rev then stopped.  Further pressing on the started button just gave me a click.  I though it may be the battery so I went and got my starter battery which is fully charged. No -go. It just clicks. It's not hydro locked because it dont have carbs. It's fuel injected.  Just guessing but maybe the starter chain broke? 

Any guesses?

if the chain broke id imagine the motor would still spin. have you tried jumping the contacts on the starter relay? just because it clicks doesn't mean its good.

A dirty side stand switch would prevent it from trying to start.

Ride safe, Ted

solenoid wouldn't click though.  .02

Dirty starter solenoid will click but not conduct any voltage to run the starter. Easy to verify and diagnose and easy to take apart to clean the contacts

The C10 starter motor drives the alternator shaft via a centrifugal clutch.
The alternator shaft then turns the crankshaft via the alternator chain when starting the engine.
If the tensioner for the alternator chain breaks, it can jam against the clutch basket preventing starting.
Easy enough to check. Just gotta remove the clutch cover.

We didn't think of the most obvious.
Are the Battery leads clean and tight?

Ride safe, Ted

I'm regretting that I ever bought this bike.
I'll short the solenoid and see if the starter turns.
 If the fails I will pull the clutch cover. Any chance of reusing the gasket?

Im in luck , I think. I stuck s screw driver across the solenoid, big spark. Now it starts every time. 

yup. a new solenoid would be a good idea at this point.

I'm regretting that I ever bought this bike.
I'll short the solenoid and see if the starter turns.
 If the fails I will pull the clutch cover. Any chance of reusing the gasket?

I've reused mine many times and no leaks.
I just smear a thin layer of Blue Hylomar on it and bolt it up.
Glad you got it sorted.
Yup, new Solenoid needed.
They are horribly expensive though 
https://www.ebay.com/itm/363327143252

I'll order one today just incase it happens again.
Finally got all 4 of my bikes running.
Two connies on the right are both converted to fuel injection, the Yamaha came that way from the factory. The Honda on the far left is still carbureted at least for a while.  I am going to move the naked one to the garage and update it with all the software improvements that I made on the last one. 

Wife said 2 of these got to go but I don't know which ones to keep!

One of those that you keep had better be the wife. LOL

No debate there. Wife is a keeper.
I want to keep one of my Connies. Probably the naked one that has been chopped down. It's the oldest one but I like driving it because I have lowered it and put pull back riser and a honda handle bars.

I wont give up my yamaha either. Its the youngest one and I also enjoy riding it on long trips. 
The little honda magna is a real kick to drive. Its got too much HO for a small bike.  I just got it, fixed it up and made it all pretty but I guess I will let it go too.

So its the little Honda magna 750 and the 1999 C10 up for sale this weekend. If anyone wants to take over the Connie I have all the parts to return it to stock if you are afraid of the EFI changes I made.

Ordered a replacement for the starter relay.  https://www.amazon.com/dp/B078S7BJ8V?psc=1&smid=A1GSUR6QOCZ9BO&ref_=chk_typ_imgToDp

Went to install the new starter relay and found the real problem. The nut holding the positive lead from the battery was loose and corroded.  I could wiggle it and make intermittent contact.  So i have an extra relay for some future project.

I have never seen a C10 starter  relay go bad. The contacts will get dirty or corrode.. take it apart and clean it.
No need to replace it. I tried to tell you this earlier but maybe i wasn't clear enough. 
Glad you found the real problem.

ive had one go bad in a CB750 wayyy back. overall its rare but it can happen. just .02. glad it was an easy fix.

Went to install the new starter relay and found the real problem. The nut holding the positive lead from the battery was loose and corroded.  I could wiggle it and make intermittent contact.  So i have an extra relay for some future project.

See Reply #7...

We didn't think of the most obvious.
Are the Battery leads clean and tight?

Ride safe, Ted

Ride safe, Ted