Today was not good for me. I went riding but here is what happened after about 1 1/2 hours of tight woods riding (using 2nd and 3rd gear; allowing to idle down long hills and up to 1/2 throttle everywhere else). My bike began backfiring when I would let off the throttle. It soon quit completely. I figured that I had fouled a plug. I waited about 5 minutes, pulled out the hot start and eventually cranked the bike up. I went straight back to the truck. I then changed the plug (Splitfire SF 430C). I inspected the plug taken out. Although it was black and sooty around the outside, near the electrode was brown and had a few specks of white. Assuming problem fixed, I cranked back up, went 200 yards and yes, it quit. I could not get the bike cranked with the hot start in or out. I finally pulled out the choke in desperation and it cranked. I got back to the truck, pushed in the choke, and it quit. Riding over for today! After I got home, I washed my bike off (had been pretty muddy) and thought that quite possibly the vent hoses from the carb were plugged with mud. I cleaned them off well and then tried to crank the bike. It fired up with the choke out. I rode down the street and back (About 100 yards) and my bike quit in the driveway. Have not check the plug yet. So a long story made short, MY BIKE'S FALLEN AND IT CAN'T GET UP!!! Spec's: '98 WR 400 WB E-series, 10 discs Snorkel removed WB Power Filter WR timing 180 main jet 50 pilot jet (at least dealer was supposed to move it to a 50) Air screw 1 1/2 turns Elevation @ 800 feet Rode about 3 weeks ago after getting the bike serviced and it ran superb. Help would definitely be appreciated.