I have noticed that about 3500 rpm's and up my bike seems to vibrate more than my buddies 07 night train with the 96 ci motor. Does anybody else with a 07 or 08 springer think this too? I would think that with the balanced engine it would'nt but maybe it is because of the extra ci's. Still runs good though.
A 45 degree V twin is going to shake and vibrate, even with a balance shaft. Just as with the rubber mount engines, there will be certain engine speeds where the balancers or rubber mounts are more effective, and speeds where they are less effective. The trick is to design the balancers or the mounts for maximum damping at the most common riding speeds.
Assuming you aren't talking about the normal amount of vibration, there are several possibilities that could make one worse than another. A common problem is uneven combustion pressures between the two cylinders, caused by the "close enough for government work" map from the factory. A really good tune that maps each cylinder separately will go a long way toward making the bike smoother. Another factor is the exhaust system. Check for proper clearances, no binding, all clamps and mounting bolts properly tightened, etc. A good idea would be to loosen everything and then retighten, starting at the heads and moving toward the rear. Be aware that some aftermarket systems can worsen the vibration, while some seem to improve it.
If your vibration starts getting worse, have your crankshaft checked for runout. I don't want to cause you undue stress or alarm, but some have in fact had severe vibrations from crank runout.
Jerry