I had an issue with my newly acquired yz426 not revving out. I did some checking and the neutral switch was already disconnected. So I increased the jet size from the 162 that was in it to a 165 then a 168 with good results for each fatter jet. The bike has an aftermarket pipe & muffler but I don't know what brand. So far so good but now I notice after only a few minutes of riding the coolant is spewing out as if it's overheating. Does anyone know if this is likely to be an overheating problem, or maybe just a bad radiator cap ? Has anyone experienced a bad cap? I just got the bike a month ago and haven't had time to work on it till now and planning a new years trip to Ocotillo Wells. Time to get busy huh? Thanks for any input you might have.