fine tuning my jetting

[ESR250R]

well i finally got my cylinder broke in (4 gallons of gas) and i decided to go WOT to check my jetting. when my cylinder was stock with airbox lid on i ran a 152 for a main, and with the porting lrd suggested that i use 162-165 for the main (with the airbox lid off). well i put the 165 main in and ran it threw the break in like that and when i went WOT it started cutting out. i checked the plug and it was a coffee brown center with a light tan outer. i went to the 162 and that just made thing worse. so i guess i need to step up to a 167-168 or 170. does this sound right? what are you other ported 250r riders using for jetting? thx

[ESR250R]

btw thats the stock carb

[powerslider]

Try a new plug, usually your rich when they break up or miss at wot. I would think your rich with that jetting on a stock carb, 158 would be my guess, drop one at a time till it clears up and keep doing plug chops.

[Bean]

u still hav unused oil in your head/piston area, ride it a few more times and see if it clears up, if it dont, start goin down

[ESR250R]

well it was a new plug when i put the top end together.

well it was a new plug when i put the top end together. But you will get more accurate plug readings if you use a new plug for a few minutes ride.

You can allways reuse the "test plugs" later.

[ESR250R]

nm i figured out the problem it had nothing to do with my jetting. i needed to gap my plug tighter, once i did that it ran great. man that ported cylinder pulls like no tomarrow.