[rrsouthwick]

I have a stock 250r with a FMF fatty pipe and powercore silcencer. FMF told me to use 158-160 main. It was too rich and I had to go back down to a 150 that I was running with my stock exhaust. I took off snorkle, I use a K&N filter. I was running at 3800 feet, but I usually ride Glamis. What filters and Main Jets should I be running at Glammis? Is there a big difference between sea level and 3800 feet when it comes to jetting the 250R?

 

[89_trx250r]

my r has the same setup you do but its an 89 though. mine is jetted at 162 main and it is still a little rich but it is worth for being reliable. if i were you i would only go up two or three sizes at the most. and always have a fresh plug when you change the jetting. also an outerware is a good idea as well.