Exhaust popping, losing power when hot

[jimjumper]

Yes, the drain bolt in the carb. I loosened it so I could get it out quickly and then started it. When I engage the mower, and it starts to run rough then dies, I removed the bolt. I had a pint in less than 2 minutes (maybe 80-90 secs?) like the flow test said. It may have taken a second or 2 for the flow to catch up to the carb intake but I can't get from the clutch pedal engaging the mower to the other side before it dies, so there is time for the fuel to get to the bottom of the carb, I assume. But, if I remove the bolt to check if the carb has fuel while running at full RPM, there isn't any that isn't being picked up by the carb. The carb idle screw is 3/4 out and the main jet screw is out 5 turns.
I'll replace the battery tomorrow and pull the carb. i doubt I'll be able to actually see anything wrong with it but I have a rebuild kit i haven't used yet. I have replaced everything electrical at least once and sometimes 3 times so I am thinking that once I am convinced I have a good carb I'll start backtracking and start swapping condensers, then the coils, then the points, etc. I have plenty of parts!

 

[Paystar]

How big are you on keeping it totally original? I'd just go 12V alternator and Pertronix electronic ignition and be done with it. Simple and zero maintenance.

 

[EdGooding]

if I remove the bolt to check if the carb has fuel while running at full RPM, there isn't any that isn't being picked up by the carb. The carb idle screw is 3/4 out and the main jet screw is out 5 turns.

Assuming that your fuel valve is open at the sediment bowl, you should get a steady stream from the fuel bowl drain at ALL times. You either have a fuel line blockage or your float is sticking in the fuel bowl.

Also, there is no way that your main jet screw should be out five turns. The spec is 1-1/2 turns out from closed, but some folks find that a tiny bit more is better.

 

[jimjumper]

Still trying. installed new carburetor and shut off valve. Starts easy and runs well with just a half turn on the idle and 2 turns on the main. I ran it for a half hour on a flat area and thought I had finally solved it but as soon as I went down the hill and got to the bottom it started running rough. I stopped and let it get back up to RPM's but as soon as put it under a load to drive it back uphill and home it didn't make it up the hill. Drove around the hill to get back home, only a small hill that way, and the only time it ran rough was the few seconds up the small hill. Drove back to the barn without problems. The generator is running hot about 140 deg. on my heat gun but its putting out 9-10 amps at full power so at least I am getting full electrical power. Am considering changing to 12V if I can't figure it out but would rather not eat the $250 generator and cutout. Should I hire a mechanic and get a second opinion maybe?