Hi, I have a Yamaha Blaster with the mods listed below. I went riding last weekend and it started to bog out at about 3/4 to full throttle of each gear. I thought that my main jet would be clogged up so i went home and took apart the carb but there wasnt any dirt in any of the jets. I also cleaned my air filter but it still bogged out at 3/4 to full throttle and sometimes backfired and stalled out. Im thinking that it is running to rich but it just started doing this last weekend and it ran fine for months before that with the same jetting and everything. I run a 310 main jet because thats what came with my Toomey Pipe. Should I order a size 300 and 290 main jet and try running those or will it run to lean? P.S. there wasnt any change in the temperature or altitude outside.

 

what does bog mean.. I think that may be happening to me too.

 

Bog as when the engine cuts out or releases amount of throttle for a second.

 

it cuts out and dies and sometimes backfires

 

Those sound like symptoms of lean.
Try this, ... put tape over the snorkle opening, and cover it about 40%, closed. Then go for a test drive, the tape over the opening will make it run very rich. If it runs better, then youll know for sure, it too lean.
If it gets worse, try a test run with the air box lid off... this will make it run much leaner. If it runs better with the lid off, then its too rich.

 

i think it might be running to lean because i already run it without the airbox lid

 

If you do anything to effect the air fuel ratio you need to rejet. If you pulled the lid off and didn't go up in jetting you are lean. Backfireing is deffenetly a sign of a lean condition. Rejet or smoke your top end

 

I didnt make any changes to it I've always ran it without the airbox lid. That is why im not sure if its a jetting problem because it ran fine for months with the same jetting and all of the sudden it seems like its running to rich because its bogging out and I didnt make any changes to the quad and the carb isnt dirty and there was no change in temperature or altitude