Runs rough after warm up

[Cholt]

My 1988 GL1500 runs great before the engine heats up. After about 10-15 minutes it starts sounding like it’s working hard, even shakes the slightest bit. Example- 60mph in 5th gear running 2200 rpm. Riding level sounds fine. Start going uphill it starts groaning and the slight shake until I get to the top. Also in town running 30mph in 3rd if you give it the slightest gas it does the same. Something isn’t right. Carbs are rebuilt and synced. I’ve got fire and good compression at all cylinders. The temp gauge never goes over 1/4 unless I ride a distance then stop and go, then might go up to half. Ideas?

[Cholt]

I’ve only had it for 1 1/2 months. Seems like it’s been pretty well maintained. 102,000 miles.

[joecoolsuncle]

it is working hard. its called lugging. if you could see the pistons rattling, you would quit that!

[Cholt]

I haven’t had it long enough to figure out the problem, but there’s definitely a problem. Guy I bought it from told me at least 3 times that it had a new alternator. By searching through these threads sounds like a Chinese alternator can give it the exact symptoms I am describing.