bought a used 2006 250 GV for my son to learn to ride on. Bike had been sitting in previous owners garage for years (like so many). Did the normal carb removal, cleaning, remove and blow open jets, make sure floats work etc... Had to replace the fuel pump as the old one had a stiff diaphram. Got the bike to start and run, but only with the carb intake open (no restriction). As soon as I place the air intake plenum back on, it dies immediately. Air box has brand new filter. I even went out and bought a conical air filter for that carb intake (45 mm), thinking less restrictive air intake, but same thing. With the conical air filter, it will run, but not rev, or deliver any power. I adjusted the idle mix screw both ways, but same thing happens. The main vacuum slide opens main jet needle and operate smoothly. Without the air cleaner, the engine runs very strong. I use rear brake to simulate load on engine. There is one thing I did modify, and that was the pilot jet. It was clogged so bad, no amount of carb cleaner, air pressure, even bent carb cleaning kit wires, trying to open it up. finally, ran a very fine drill bit (fit into the pilot jet opening freely, until it hit the jam) through the jet and got it open. Bike now starts, but appears too rich?
Normally with carb problems, getting enough air is rarely the problem. Stumped? Maybe nothing to do with carb operation?? Looked through the forum, but no luck. Once, my frustration level is too high, my logic for trouble shooting appers to disappear quickly. Welcome suggestions.
