I recently purchased a 1986 1100cc sportster evolution, rode it a few times and it ran great but really rich. Either way there was nothing wrong with it except it was blowing some black smoke out of the exhaust.

One day I went to start it and take it for a ride. It started rough, idle was rough, and ran rough when I gave it some throttle (missing, backfires, runnning on one cylinder). Can't bearely make it out of the driveway it runs so bad now. This problem came out of nowhere!

So I cleaned the new plugs because they looked fouled and then checked for spark and timing position. Everything looks good, have no idea how this could of changed so quickly?

Any help would be greatly appreciated!

 

If it were me I'd start with cleaning the carb. Might check the tank/fuel filter for gunk too.

 

Yeah I removed the carb and cleaned it real good, also checked line, petcock, and tank. Problem still exists and now I think the float is sticking because the carb is dumping gas all over. I feel like the bike is not getting enough gas and I can't seem to figure out why.

 

Your float is too high right now. Is it a keihn carb or mckuni?
While you have your carb off, pull the intake & replace the 2 gaskets where it mounts to the 2 heads. Take your time re fitting the intake so the gaskets dont mis align & tighten the intake little by little on all 4 fasteners.
Keep me posted.
Hatch.

 

Hatcgetman,

It is a aftermarket zenith carb with an adjustable main jet and adjustable air at the top of the carb. Won't be able to work on the bike for a week or so but I will make sure to replace the intake gaskets. Should I get a rebuild kit for the carb? I only ask this because there is no adjustment for the float.

 

You should be able to bend the tabs on the float to set the height. A kit is always a good idea but if you dont have one, be careful that you don't tear gaskets when you pop it open.

 

Those are a simple carb you should do ok with it follow hatchetmans advice . Grab a couple extra sets of plugs even new ones once they oil and soot foul real bad they never seem to act right without grit blasting them . Also check you plug wires , can't hurt .