YFZ is bogging down past half throttle

[RedneckYFZRida]

My YFZ bogs down past half throttle every now and then and its starting to piss me off because it did it the other day int he middle of a hill climb. Nebody got any idea about whats going on with it?? When it does it I can just pop the choke out and hit the gas and it works just fine again.

[racemx]

fuel screw and your jeting is off. clean you carb to

[rpyfz450]

This may sound rediculous, but if your ATV is a 2005 or earlier, turn on the headlights to see if the problem goes away. If you don't have headlights installed, reinstall them or else get the Yamaha "resistor kit". With the headlights installed, you should make the problem disappear and reappear by turning on/off the lights.

[400EXBill]

Not sure if this is your fix, but it was for me. My 400EX would bog every once in a while past half throttle when I would get on it at the face of a jump or hill climb. Almost nosed it a couple times on the jumps. Well, as it turned out, it was dirt in the carb. There was dirt in the float bowl, main jet, and accelerator pump. I say take the carb apart and clean it like I did. Fixed it for me. :D

[rpyfz450]

Originally posted by 400EXBill
My 400EX would bog every once in a while past half throttle when I would get on it at the face of a jump or hill climb. Almost nosed it a couple times on the jumps. Well, as it turned out, it was dirt in the carb.

That's funny because years ago I had an ATV that would die out only over whoops, but could kick started easy afterwards. When I dropped the float bowl, I found a huge, single grain of sand right under the main jet. Apparently, that grain would get tossed against the main jet opening and held there by vacuum as long as the engine was running. Once the engine stalled, the grain dropped to the bottom of the bowl. The cycle would then repeat itself the next time I rode over whoops.