Need carb tuning help

[dabomb_350x]

I am trying to jet a couple 300EX with different set up and need help figuring out what jet sizes to use and where to place the needle jet or if I need a new one.

A friend of mine has a '93 with hole filters in box lid, K&N filter, 350X air tube and a cobra jet exhaust. He was told it has a 330 kit in it, but believe it is just a high compression pistion.

I also have a '96 that I am rebuilding with at FST 330 kit in it. I plan on running with a EHS air box cover, K&N w/Outerwear, 350X air tube and a TC full race exhaust system.

I also have a '01 that has a K&N w/Outerwear, 350X air tube and Supertrapp 4" Racing Exhaust system.

Also what octane of gas should be used.

Would this info be found in like a jet fit.

[bwamos]

Cant really help you with the jetting, but I can help with the octane.

11:1 and lower octane is generally good with premium pump fuel. 12:1 and up requires higher octane. (race fuel or race fuel mix).

[JohnT_98300EX]

The jetting for the stock 300 with the pipe and air box relief will depend mostly on what your pipe manufacturer would recomend. Check the cobra website for any starting point recomendation. For my ride I checked the FMF website and they had a real good starting point for my bike and pipe.
In my case I went with a 128 main jet and no other internal changes to the carb. I added 4 Uni filtered vents. (all they recomended was air box vents, no set amount) My plug is a decent paper bag color and the bike runs much crisper than with the stock jetting. Once the weather warms up I am going to try a 130 and open the other 2 filter vents.
When I started it had a stock pipe and muffler and stock jetting. It started well and ran right.
It still starts well, idles, and runs,,,more right.