The bike started running rough, it came on suddenly but not as fast as an electrical issue...
Clue # 1: probably fuel related.
So...I flipped the fuel valve to Reserve. No change. Crap.
I was near a gas station, so I figured why not pump a gallon and see what happens. No joy.
Clue # 2: It's not the fuel itself.
The O2 sensor is located on the starboard side crossover tube, so the AFR readings on my AFM are starboard side biased...the meter peg-bounced to 18+ AFR, but wavered...
Clue # 3: Probably the starboard side.
I noticed that the motor would smooth out a bit and blast along just fine once it was on the needle heading to the mains...also confirmed by the AFM.
Clue # 4: probably the pilot circuit.
So, I next drained both float bowls. The starboard side had some fine-grit type "dirt" in it; port side was clear.
Clue # 5: Probably something clogging the starboard-side pilot circuit, most likely the pilot jet.
So, I dropped the starboard side bowl & pulled the main jet and pilot jet; the main looked clean & unobstructed, however the pilot jet looked slightly occluded. Bingo. I used a plastic dental pick to gently clean out the innards of the pilot jet.
Clue # 6: The clear plastic inline fuel filter was a bit discolored.
I then replaced the fuel filter with a larger clear filter - when in doubt, change it out.
I put it all back together, & it fired up happy again. Took it for a ride and all was well.
