Carb Jetting

[MO Predator Racer]

I know alot of people run there idle jets pretty rich on gas or alcohol. Another racer and I have the same motor and we run stock predator which has header pipe with muffler, air filter adpater, no govener, and 10.8 springs. He runs his idle alot richer than me but his main jet is a tad leaner than mine. Does running a richer idle jet and leaner main jet do anything? I just find it strange how his motor is the same as mine but jetted leaner in the main jet but jetted richer in idle jet. Is it because when you get off the throttle the rich idle jet will put more fuel into it and then that will equal out with the leaner main jet?

 

[mike97760]

On mine I wanted to richen mine if possible with stock jets. I have collected a small pile of stock carbs and took them apart to compare jets. There ARE differences. I put the largest idle jet and main jet in my carb. Its a little stronger at 4900 and fouls the plug eventually fouls if idling too long. Put the original back in.