hi all i have a 84 softail with a s&s super carb kit on it every thing else is stock. the bike sat for a few years so i took it in and had every thing gone over on the bike to get her in running order. the bike ran fine for about 600 miles and then it started to sputter and back fire and foul out the plugs as if it was running to rich. so i took it back in to the shop and they replaced the plugs, intake manifold seal and put in a #72 main jet. the bike ran great for about 20 miles and back to the same problem. seems as though she is running rich still spitting out black smoke when i get on the throttle and while riding it sputters and backfires at lower rpms. so any one have any ideas on what to do next?

 

May be electrical, what ignition?

 

It doesn't sound like a simple running rich thing, as it starts out each time running great for awhile.

 

We have seen this happen when the ignition module is old, heat trips some circuit. We replace them and problem solved.

 

I'm not sure on what ignition is on it I guess whatever came with the back from the factory I'll look into a new one hopefully that will fix the problem

 

Make sure the enrichner plunger is seating. If it has the S&S backing plate, make sure the button on the plunger has some clearance above the slot in the tab on the paddle when closed. If not bend the tab down a small amount.