Loss of power...

[DaveD(MI)]

99 I/S, Just had the carbs synced and valves adjusted. Dragonpacks exhaust with brand new stock air filter. mobil synthetic motorcycle 10W-40, 11,000 total miles.  Can't figure it out, just seems like it doesn't have the get up and go like it did a few years ago. Can barely stay ahead of the new Harelys. Clogged fuel filter? Ran a tank of seafoam about 1000 miles ago. Any thoughts?

[Thunderbolt]

take a sheet of paper large enough to cover the exhaust tip and hold it over the tip while engine is running one side at a time.  If all three on that side are firing, you will notice that the paper will be held out by the exhaust pulses in a rhythmic pattern.  If a cylinder is not firing, the paper will drop to the tip occasionaly.  If you find that you have one not firing, either a plug on that side may be fouled, or the low jet may be clogged.
Is the tank vent tube kinked allowing the tank to build up a vacuum?  When you stop and open the filler lid, does it pull air in with a whoosh sound?

[Daniel Meyer]

Make sure the petcock is working correctly. A blown or partially blown diaphram will cause all kinds of symptoms.