Hi, I just bought a 1985 atc 250r with a paul turner pipe, it runs good but when I took the carb off I looked at the jets and the main was a 140, my manual says stock should be 142, shouldn't it have a bigger then 140 jet because of the pipe? The slow jet is a 52 which is the stock size. I live in AZ 750 ft above sealevel.
Thanks.

 

Is that all of the mods you have? or you don't know? How does it run? What type of riding do you do? Is it the Hi-rev of mid range pipe? If it runs fine, then I wouldn't worry about it. Give me more information and I'll help you more.

 

I don't know what type of pipe it is. I do mostly desert riding and sometimes go up to the buttercup dunes. The motor has no port work it is mainly stock, has pipe and k/n filter with airbox lid.
Thanks for helping.
Carlos

 

The pipe will be stamped below the Paul Turner signature on the name plate.

If you don't know anything else about the bike, then try this. Pull out the plug after you give it a ride. It should look brown and moist. It it's dry or white in color, then you'll have to get a bigger jet. It it's brown in color, then you're fine.

If you ride it in the dunes, I'd take the airbox lid off and fatten up the jet anyway. You shoold get a little more power that way. If you want to take it further, then get a 39mm PWK and a set of boyessen reeds and you should get even more. If you go any further, you'll then have to port and deck your cylinder to get more power.

 

I checked the pipe where it's stamped and all it says is paul turner racing. Can you give me an idea on what size jet I should start at, I have a 140,142,145, and a 148 main jet. What mods do you have on your 85?