Need help figuring out why my Harley Sportster isn't running good?

Question

I have a 1988 Harley 883 Sporster that has been giving problems. I have had it in to the shop 3 times and every time I get it back it still runs bad. They replaced the ignition module and re-jetted the carb. but it still runs bad. It will run good for a while then after it warms up it misses. When I hit the gas it falls flat on its face. Other times when I am riding it feels like the key is being turned off and back on. Anyone have a suggestion? The gas line has been replaced, ignition module, plugs and re-jetted, I am at a loss.

Answer 1

Have you checked the coil?That what that sounds like could be the trouble.Coils many times don't show a problem til they get hot.

Answer 2

That does sound like a faulty coil.

Answer 3

I need to know other details like is the bike stock or have there been modifications to it like exhaust?

Answer 4

the rear cyl is dragging the engine down

perform a rear cyl leak down test

common problem on sportsters