I need help jetting

[MasterBlaster]

I have a 05 yamaha banshee with fmf fattys and powercore2. I recently changed my jets from a 270 to a 260 with 27.5 piolets. Now when i ride my radiator overflows but before it didnt. It starts and idles better with the 260 but runs hotter. In six gear it seems its not pulling as hard as it did before. Im 27 feet above sea level. Thanks.

[overrevtricky]

That certainly sounds lean. Like some guys say on here, start with a high number rich jet, maybe 300 in ur case, then step it down until u find the sweet spot. Also plug chops are very nice! I have used both methods in the last two weeks and have spot on jetting now.

[GrMeyer]

Pilot and airscrews are the only ones that mess with idle - 1/4 throttle. Mains only effect WOT

 

http://www.dfn.com/benkaren/jetfaq.html

 

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