Hey i have an Indy 500 as well, a 2006 model in the edge chassis but still has the 488cc fuji engine that has always been in the indy 500s. My sled did the same thing on my trip last week, but only does it when its all the way warmed up and its warmer out. It was roughly 30 degrees F out when it was doing this, yet it ran amazing the week before when it was 7 degrees F out. This leads me to believe it would really benefit from dropping a main jet size one or two steps. This sled is all stock, with 3100 miles on it. It only does it when the outside ambient air is close to the freezing mark, because the factory jets it a little rich from the factory just to be on the safe side. Check your compression and all that as everybody said, but if everything checks out ok I would be willing to bet it would benefit from a size or two smaller main jet. Good luck!
1998 Polaris XC600 (with a XCR sleeper hood on it
2006 Polaris Indy 500
1969 Chevy C10 "69CRUZR"
-383 stroker 450 hp 479 ft lbs of torque
2006 Chevy Colorado -daily driver
New Project Truck, this one for my Pops!
1953 GMC 5 Window Shortbox Stepside
Drivetrain: 2006 5.3 Liter v8 with 4l60e from an 06 Silverado.
Full IFS front suspension kit w/rack and pinion steering, and 4 link rear from TCI Enterprises.