ok here is the deal..my friend recently bought an '03 raptor which was completely stock, and it was running lean but not terrible. he put on an HMF full exhaust, and a pro design air filter kit with the k&n filter and he is running the airbox lid. he has it jetted 150 and 155 with the stock pilots, and now this thing is running terribly lean...pipes glow bright red within a minute of the quad running. carbs have been gone through and valves checked....anyone have any jetting suggestions??

 

That jetting seems about right with the lid on. Is it running OK otherwise?

Glowing pipes can usually be fixed by changing the pilots if it is running good otherwise. Try changing them to a #27.5.

 

its really not running good though. it acts like the parking brake is on, but the parking brake is completely gone so that can't be it. the quad will idle ok and as soon as he hits the gas it bogs out...about half the time it will actually die.

 

i should also note that his plug actually doesn't look bad...tannish brown, not black or white

 

Has the parking brake recently been removed? Are the carbs secured in the intake carb boots? Have the carb vacuum connections been checked to make sure they are secure and crack free? Even though the idle circuit is probably on the lean side, the cutting out problem needs to be addressed first IMO.

 

Garyc660R is still around? That's good. I thought all of the pro 660 drivers were gone.

If the bike cuts out and falls on its face right out of idle, then larger pilots should fix that. If it is falling on its face higher up in the range, then the mains may need tweaking.