83 runs great 10 mins tops?

hi there, ive been working on this one for a while as some of you know....i think ive got the points set right as it runs fantastic for 10 min...then it bogs down and just quits. wont start for at least 10 - 15 min. ive tested just about everything on the bike with the exception of the condenser...as its an 83 it has a different plug on the stator than all my other older ones and i cant find a kit for the rebuild with that plug so im using the old one. sanded and set points many times now. im wondering if anyone can confirm if a shitty condenser can run good for ten min then quit? or am i missing something else? Racerx?

Have a bike that does something similar. It quits after awhile and right before it quits it almost sounds like the timing is off or its firing at the wrong time. I believe this to be the condenser because this bike was rebuilt not long ago, the crank I had rebuild was pressed together slightly crooked and the points were opening twice in one revolution. It would cut out mid range but idle and run fine down low. While trying to troubleshoot that issue I had changed the condenser, it still ran bad in the mid range, then I ended up noticing the flywheel was out of balance and points opening twice, took motor back apart and swapped cranks. That fixed the mid range issue but if riding it in 75F degree weather it quits in maybe 10 minutes, if 55 degree weather it might take a half hour. This one will start up in probably less than a minute but will act up again in just a few minutes. The bike could be rode for hours before the rebuild with the old condenser and not quit.

Is your gas tank venting?

I have a 1973 Suzuki 125 rv that does the same thing , I have to ride it around in a circle because you never know when it will quit . Been pulling my hair for a year . Just when I think I have it - it stops . Starts back up and runs for 2 min. I want to get it reliable because it's a dream to ride .

Three things come to mind: Valve lash, fuel flow restriction, dying condenser. It's possible that it could be something else, like sticky valve, but such problems are vanishingly rare with these motors.

After this much time and headaches, I'd throw a new condenser at it and go from there.

All three of you should re check the valve lash.

I've had primary coils and condensers do the same thing. Valve lash is the easiest to check.

My 78 did EXACTLY the same thing. Ran great until it got hot, then got progressively worse over 5 minutes, and then would not run.. Next day, same thing. Change the condenser. You can't visually detect a bad one. Unless you know how to load test a condenser. Changed mine, zero problems since.
(I did manage to see an actual spark jumping from the spark cap to the head - high voltage, no current).

Won't hurt to check valve lash too, but that is a 35 year old condenser.....