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View Full Version : need some 350x carb info



fcf35
06-19-2013, 08:18 PM
Got my 350 going last night and it runs good but has a little backfire on decelleration.I know I need a bigger main but I was curious what other people are running.I have a bone stock motor with aftermarket header and a scorpion muffler with spark arrestor and all intact.I don't have a jetkit yet so I was just gonna see if anyone is running a similar setup and what main their using.forgot to mention I'm using a 400ex Carb.

Jason125m
06-19-2013, 08:24 PM
I can't tell you which jets to run because of differences in elevation, but i can tell you that backfiring on deceleration is your pilot jet, not your main jet.

fcf35
06-19-2013, 09:15 PM
Yeah I'm gonna try a 42.the motor seems to get hot really quick.there's a very slight hesitation at 1/4 throttle and then its balls to the walls.

RIDE-RED 250r
06-19-2013, 09:27 PM
X2 on what Jason suggested.... Backfiring on deccel is most often a lean pilot jet

Poco Loco
06-19-2013, 09:30 PM
Yes pilot jet. Go richer. (biggger). Also, the air screw adjustment. Double check the 400x specs and use that as a starting point. You can try 1/4 turn increments as you test ride. make note of the changes. Work toward the best working setting. And make sure your exhaust is sealed properly. (gaskets). If the needle clip is set high on the needle, lower it to the middle setting as a starting point to work from. That will also richen up the off idle response.
Good luck

fcf35
06-19-2013, 10:16 PM
Man I really do appreciate it guys.I'm still learning a lot in all aspects of motors and appreciate the help along the way.I can read a manual and tear apart and put back anything but when it comes to fine tuning I'm still a little new.until I got my first 350 it was simple to get one going good with minimal work.clean Carb,check compression,valves etc.I've rebuilt dozens of 110-200 with ease but the 350's have gave me hell from day one.oh well I'm not gripping at all I actually really enjoy working on them.