350X/supertrapp question

[87ATCFREAK]

I just got my 350X all put together and started it up. Its back firing after you let off the gas. The back fire is rather loud and not normal. Could this be due to the main jetting being incorrect? What is the proper jetting that should be in the carb for running a new supetrapp exhaust? Any information will be greatly appreciated! :confused:

[thebutelr]

I just got my 350X all put together and started it up. Its back firing after you let off the gas. The back fire is rather loud and not normal. Could this be due to the main jetting being incorrect? What is the proper jetting that should be in the carb for running a new supetrapp exhaust? Any information will be greatly appreciated! :confused:
I think that its normal for a 350x to pop and crackle a little bit on decelleration, I know mine does a tiny bit and I have a supertrapp and the jetting is right, if you your backfire is excessivly loud you might want to check your timing. As for your jetting there's no way of telling what you need to bump up to. From what you've said its either lean or out of time. Do a plug chop and post back on here what color it is and we'll go from there. Hope this helps. Later

[87ATCFREAK]

I will check the plug tonight and reply back as to what color it is. I'm pretty sure it isn't the timing. I've ran into the timing situation before on other motors. Do you know the number of the main jet you are running?

[thebutelr]

I will check the plug tonight and reply back as to what color it is. I'm pretty sure it isn't the timing. I've ran into the timing situation before on other motors. Do you know the number of the main jet you are running?
I'm running a 152 main in there right now, but I am running a 10.5:1 wiseco, mild grind web cam, no air box lid, & all the disks in my pipe. Mine is still a tad bit lean so I think I'm going to put a little bit bigger main in there since its warming up.

[BLAZERONE22]

You just need to go a size up on your idle jet... One day I'll do that to mine also... lol

[NOS_350X]

Most people forget about the Pilot jet you gota change that one also. For just a pipe i would think about 142 or 145 should be about right but thers no forshure way to tell you.

[hrc200x]

air leeks at exhaust fittings can cause poping. I have two 350's with supertrapps, and both pop.