I was wondering if anyone has a similar setup? I bought a 96 300ex all stock except it has a DG pipe and exhaust with Supertrapp spark arrestor (12 disks) and holes drilled in airbox lid. It still has stock jetting, (122 main, and 3 1/4 turns out on pilot) so it runs lean. What size main jet are you all using with this type of setup? I was thinking of putting in a 128 or 130 main jet, cause I happen to have those already. Will this do or do I need to go larger?

Thanks!

 

Put in the 130,test it,and if it don't work use a bigger one.

 

Ok, I put in the 130 main and it runs a heck of a lot better than before. When I hit the throttle, the responce is instant. Here is my problem though, it still seems lean. Pipe glows when holding throttle open 1/2 way for a minute or so and it backfires / sputters on deceleration. I have the needle clip in the middle and turned the pilot out 2-1/2 turns. I am thinking of going up another 2 steps, like a 135 or so. Will this be too lean? Do you all have any suggestons? Raise needle before increasing main? I know it is just trial and error, but any suggestions would really be great. I have already adjusted the valves, opened up the carb, cleaned everything, and replaced all gaskets.

Thanks in advance!!

 

Make sure the bolts on your header are tight. That may cause the backfiring and/or sputtering.

 

I strongly advise that you start much higher with your main jet, depending on what altitude you run at. At 9000 ft, with Big Gun, K&N and no airbox lid, I did not start showing signs of being too rich until 130 on the main. I backed down to 128 and performance is dialed in and I know I am not running in danger of being lean. I have the needle clip set one notch richer than stock as well (2nd position from the bottom). Air is set at about 2.5 turns out and my dealer said stock is 2.25 turns.

If you are at sea level or close to it I just have to believe you are still running too lean.

Just my $.02. Good luck.