350x jetting

[Kawboyz beware]

Well I just put a new exhaust on my TRX350X/300ex quad. The carb had the stock jetting 138 main and a 42 Pilot. The bike seemed to run good but it ran alittle flat on the top. The bike also seemed to backfire alittle on decell. The pilot screw didnt seem to help I went to the local dealer and picked up a 140 and 145 mj I had a 148 from the old 400ex. I put in the 145 to start with going riding Sunday will see if it helped. as for the backfiring would I need a bigger are smaller slow jet. like a 40 or 45

[cals400ex]

the temperature will play a big role in this. a 140 or 142 should work just fine if the pipe is your only mod. you can try turnig the fuel skrew out to like 2.5 or 3 turns and see if that helps the popping. if the pilot jet is too small, go with the next size bigger like a 45 or so. also, it could even be popping from your needle being too lean. in the colder months of the year, you might even want to move the clip on the needle from the 3rd notch from the top to the 4th notch.