My Spyder gave trouble from the time I bought it with 11,000 miles. It always pulled good from 3500 with a lot of missing and stumbling at Idle and lower rpm. I took off the Two Bros. exhaust(could not stand the noise) and put a stock exhaust on it. I took the Two Bros. fuel enrichment system off but it still ran poorly. I checked all the obvious things like wires, plugs, valve clearances and MAP sensor tubes, Finally I replaced the fuel injector on the cylinder that seemed to be the problem. It now runs as near perfectly as I can imagine AND I am so pleased! I have made a lot of changes to the seating position, moved the foot controls forward, the bars back, and now have a touring stance instead of a crotch rocket. I am 6'3" so I needed that.
I have been modifying the radiator outlet system to keep heat off my right leg. I really wish they had placed the radiator at the front but that would be a difficult change.
Happy Harold in South Georgia.