300ex jetting help

[riley1374]

Guys just bought a motor with stnadard bore, 11:1 compression, cam, port and polish, head work. I am in NJ at sea level, and i am trying to figure out where to jet this thing. Gonna be using a stock carb for now. Gonna be using an FMF exhaust, K & N air filter with lid off. What pilot, main, and needle position should i be at to start safely? Thanks

[bwamos]

Start off with a 135 Keihin Main Jet, Needle clip down 1 from stock (needle up), and keep the stock pilot. Only need to increase it if it's less than 1 turn out on air screw for proper setting.

[riley1374]

Thanks BWAMOS, i would have thought it would be closer to a 140 main, but seeing you have the 330 kit i guess it would be closer to the 135 like you suggest. Anyone else have any input? Thanks

[bwamos]

135 should be ok. If it Boggs at 100% throttle, then put in a 140. And go from there. ;)

You could start at 140 for breakin. Should run ok. Then drop it to the 135 to start tuning it. Always better to be rich than lean on breakin.

Every machine runs different. ;)

Here's a very helpful jetting guide for Keihin Carbs that I usually link for people.
http://www.duncanracing.com/techfaq/Tech_keihin-carburetion-jetting.phtml