YZ jetting

[protraxrptr17]

What jets are yall running in yz426s and 450s? I used a 48 pilot and a 185 main with a jd red needle from my 450 sx-f kit. Seemed bad lean. I only rode it for a minute. It was sputtering and popping real bad. Hard to start when hot. I'm thinking the pilot may be a little rich and the main too lean. I'm using VP U4.2 and I went up about 10 sizes on my other bike when I switched from 114. The engine has not been ported. It has 426 cases and ignition, 450 crank (has a custom primary gear to allow it), 450 cylinder, 04 YFZ head, not sure on the cams.

My 450 sx-f has a 48 pilot, 188 main, blue needle and runs perfect. It has a 41 mm carb.

[hontrx265r]

make sure the ac pump is working properly that can cause what your describing. You should be in the ball park to where it should be close. They all differ with intake and exhaust setups my 426 ran 48 ncvq on 4th and 178. My 450 had 55 stock needle on second from top and 168. (the 450 was tuned on the dyno though. They both ran good seat of the pants
Still got those parts if you want em....