hello, i just bought a 2007 Yfz and im having a problem, its runnung way to lean, its back firing, and it cuts out for a sec when you hammer the throttle, i have like 2 hrs on the machine, its this a commen adjustment or dirty carb or something? anybody elese having this problem?

 

depending on elevation and humidity... your jetting could be off from the factory... buy some jets and see how they work for ya...

 

Hebs is probably right, these machines can be a little finicky when it comes to jetting...

 

lol..."its running way to lean" you answered the question right there, jet it up

 

the 07's come with a blockoff plate to the air fuel mixture srew. take it off, go buy a msr replacement $20 that comes out the bottom and allows you to adjust it wth your fingers. Run it out until you get the best throttle response then come back in a 1/4 a turn and ride it to see how it does.... Your problem should then be solved if everything is stock.....

the 04-06's didn't have it blocked off but for some reason the genusius at yamaha decided to put it on the 07'...