half throttle sputter

[schmidthouse]

Here is my problem. I have a 2006 trx450er full muzzy exhaust, dyno jet kit 128 main jet needle on 3rd clip. In Central Oregon at about 2000 elevation. I have been riding for 6 months without any adjustments to the intake or exhaust and it has been running very strong. Here is where is gets weird. Went out to the dunes and the bike starts sputtering at about 1/3 throttle. So bad that it fouled the plug. Replaced the plug and still sputtering. Pulled the main jet and needle jet and they both look good, no junk in the carb. As I rev it up and it starts to sputter the tail light starts flikering on. What the hell, it has got me baffled. Anyone have any thoughts on what it might be?

[jd31goalie]

i experienced something similar just the other dy and thought it was justa a "bug" i had been riding pretty hard (for me) for about 3 hours. stopped and refilled(myself too) went for another qiuck spin wheni noticed i was experiencing some burbling at about 1/3 throttle but would clear with more throttle. no other abnormalities noted but the sputtering continued through the ride. pulled the plug when i got home and it ws pretty good but put another plug in and am waiting for the next ride. any help would be appreciated.

[ajay002]

i have an 05' and the crank locked up. i replaced the crank and road sunday b4 last all day no problems. rode this past saturday and it started over heating. took out the thermostat had no other problems. rode for about an hour and a half then she started back firing and sputtering. after about 5 min it died. replaced the plug would fire up and idle but when u gave it any throttle it would sputter back fire then die. after a new plug wouldnt fire. i pulled it it would pop and backfire and shoot out a blue flame. then after it got hot it wouldnt do anything.?? not backfire not even sound like it would fire off. i think it has todo with the coil ?? any comments on this one? im stumpted like u to.

[mymastifftucker]

A 128 main is way to lean for a full exhaust. I have a 07 with a full DMC Alien exhaust and I am currently using the 142 Dynojet main, and the fuel screw 2 turns out. You are a little higher in elevation but a 128 stilll sounds lean. Go bigger and see what it does, I am willing to bet it will help you out.