86 250r new pipe..jetting..size????????

[brian lanwehr]

replacing stock exaust with turner pipe dg scliencer...jet in it now is 148 is that stock.....what should i start with....i live in northern ohio also is b8es stock plug???/ thanks

[smokinwrench]

B8 is stock plug.

As for jetting you could have 2 identical machines with the same mods and both will be jetted different to run properly. My best guess would be go up a couple main jet sizes and raise the needle a couple notches and do some plug chops. See how the plug looks after that and make adjustments as needed.

[skippy]

yeppers. start around 160-165.. and buy a few jets up and down from there...

[TimSr]

Start with what youve got, and do frequent plug checks. While the TRX is different, and its not apples to apples, my 86 TRX250R w/ 150 stock jet did not require any jetting change between stock pipe, PT midrange, and ESR TRX6 low end pipe. It had a K&N filter. It had been bored once or twice, and i dont remember the overbore size. I did end up dropping the needle to its lowest position (leanest) so it stayed somehwat clean at midrange. I am in NE Ohio. The biggest carburetion mistake I see is people assuming that any aftermarket pipe always requires richer jetting than a stock one without first checking. Everything I ever bought that was "jetted" was way too rich and ran like crap until I leaned it back out. My 250R was at 165 and I took it back to 140. My Quad-Z was at 500 or 510 and I took it back to 420. A a general rule for 2 strokes, the more top end oriented a pipe is , the richer you need to go, and the more low end it is, the leaner you need to go. The stock 250R pipes are very top end oriented.