Please read:

http://www.eric-gorr.com/twostktech/carbtuning.html

What jets work great for your buddy, might not be the best fit for you. Mods/weather/oil-fuel ratio/etc/etc/etc make a huge diff in jetting.

 

well i wanted to see if you guys could help me too this is my problem: i have an 89 trx 250r and my mods are a k&n air filter and a fmf fatty pipe and silencer the rest is stock at first i changed the main needle to a 168 then i went up to a 175 and for some reason i think it is lean because it bogs down some wat when like coming up on the dunes lip and i got to shift it down like to 1st gear but it is also a screamer it makes it up some pretty steep hills in 4th gear but it sucks lots of gas up compared to how it use to be when it was stock but the bog is more toward the low to mid waould rraising the needle help this and idle is set relly low is that good or not any help would be greatly appreciated cuz i dont want mess around with it alot.