I will try to explain this the best I can. I was riding the scoot (1993 Fatboy)doing about 65mph, was running fine, then the engine started stumbling as if I was out of fuel, but the tank was full. So I got off the highway, and the bike kept doing the same thing as if I was out of fuel or running on one cylinder, there was also a clunking sound (sounds like a bolt in a tin can)coming from the front cylinder or possibly the carb. I pulled both spark plugs the plugs were dry black and sooty. After the bike sat for a while it started fine and ran fine, after about a minute or two running it would act up again. Also when it acts up which is all the time the carb coughs, I noticed oil on the outside of the carb.

After doing some research I replaced plugs, wires and ignition coil. The bike seems to be running a little better but there is still the "clinking" sound seems to be coming from the front cylinder. When the bike was running a blue flame was shooting out of the front cylinders exhaust pipe. Also there did not seem there was the same amount of pressure coming out of both pipes, front seemed less pressure, and felt cooler than the rear cylinder exhaust. If it were a carb issue wouldn't it effect both cylinders? Could it be the ignition module? Or something internal in that cylinder? The bike has 43000 miles.

 

Sounds to me that its internal

 

Simple stuff first, I suggest you pull the float bowl and give the underside of the carb a shot of carb cleaner, you may just have some debris in there.

 

I would recommend posting in the EVO section...Most people that will read this are running a different motor.

 

Iam hoping its not internal, but if it is it will give me an excuse for a rebuild. Iam going to pull the carb this weekend and give it a good cleaning. I just purchased this bike three months ago so this is all new to me, I am used to ECU's and fuel injection. I also posted this in the EVO section, thanks for the heads up.