I just got my bike back together after an extensive paint job, new parts, new bearings, hoses etc... I went to start it up today and wow either my rpm gage is broken or there is a sticky part in the cabel. My diganostics is that if I blip the throttle the rpm's don't move but 200rpm's..If I rev it up to what sounds like mid 6k rpm's the tac shows the needle rising slowly even tho I'm holding the throttle at a steady position. I tightened up the connection where the cabel attaches to the head.....Didn't help any.
I think it's the tac gage because the air mixture is out 2.5 w/ 125mains and stock air filter....IF it is the mixture then I shold richen it right?
You could try shaping a bit of wood so it fits were the tach cable fits in the tach gage and then try spinning the wood piece with a drill to test if it is working properly.