I bought a 99 900 RR about a year ago (no warranty) and it keeps fouling the plugs. I've been through 4 sets of plugs. After the 2nd I took it to the dealership but that didn't go very far. The only thing they could find is my throttle adjustment screw was off. The bike will run great one day and I'll go out to start it the next, pull the choke, hit the ignition, no start and backfire. Fouled Plugs. When I take them out they are wet with gas but as far as I can tell no oil. It does have an after market exhaust on it. Could it be jetted wrong? The dealership was supposed to check that. Any ideas?