Idles for a minute dies then will start again?

[Junkyard Johnny]

I have a 75 that I just did the top end this spring. Also put in a pamco and a dual output coil from mikes. Shes been running like a charm until a couple weeks ago. I got it up to highway speed and temp then ran er home and when I got into the driveway, I sat and let it idle for a few seconds and it dies. Doesnt stumble or cough. Dies like I shut it off by switch. As I rode it the following week, it would die more frequently at stop signs. Then it started dying as I revved it at takeoff. Now its almost unrideable. It'll start but will only run for about 10-15 seconds and die. I always shut it off then fire it back up and it starts again every time. I was running non resistor plugs and non resistor caps. I put in a set of iridium plugs I had sittn because they're resistor plugs and it ran and idled longer. About a minute and a half. But it did die again. My question is, is my coil slowly frying or is it possible that not running a resistor toasted something on the pamco? The transistor? All my wiring looks good. Thanks in advance for any help.

 

[TwoManyXS1Bs]

That sounds like the typical scenario reported by owners in the '70s. But usually was idle...idle...pop...die. Yamaha made subtle little changes to the earlier models chasing that down (ign timing, cam, compression ratio, carb design).

Your situation may mean that a post break-in tuneup is needed. Retorque head, camchain, valves, check timing, maybe an eighth or quarter turn extra on the mix screws. Check for intake leaks...