Hello.
i have a new built 98evo 80cui. Wiseco hi comp pistons 10-1. Andrews cam. Ss super e carb.Have revtec top ends and single fire ignition.
i have one more oil change of brake in on the motor.
When driving slow,like up to 50km/h the engine is lugging(right word?) No problem at higher speed and when giving trottle.
Maybe wrong spark plugs?

 

As long as you keep the rpm's up above 2,000 in any gear, you're not lugging the motor.

 

Thx.
so it is only the rpm that is the problem?

 

Keep it up above 2,000 rpm if at all possible. If for some reason that you can't do that, then it's most likely that the way in which you're riding may be the only real problem.

 

With proper jetting the engine should run smoothly, even at lower rpms.
Cruising at 1500-2500 light throttle should run smooth.
Bob

 

Was just thinking the same. Will take it to a work shop when finish brake in,adjust the carb and jetting. Looks line it needs a little more fuel. Also tried a high flow petcock on,overflow on the s&s.

 

seems the 2k rpm is the magic number. lower than that except in 1st and depending on final ratio possibly 2nd. my 1974 & 2001 do not like it as well as any other i rode, you will get driveline ******.