never could figure out the cause to the problem, but what we did was turn the fuel switch to off while resting or letting the sled sit for extended periods. acts like its flooded. this was on an 89. thought perhaps a kinked vent line but never found anything. personally i think it had to do with the fuel cutoff switch. however, it was an extra sled that sat alot so whoever rode it was instructed to turn the fuel off, or pull, pull, pull. you might try that and see if goes away. as for jetting, give me your target altitude and temp and i will throw some numbers at you.