argh, 300ex jetting

[fastmofo]

Ok, My 300ex has a twin air filter, and Big gun full exhaust, the jetting is messed up to hell and would like to find out what stock is like to go from there..

right now it pops on de acceleration and does not like to idle when cold.. I have jetted sleds a million times so my guess is its running lean, have been lazy and havent even checked plug..

So im wonder what stock Pilot jet and Stock Air fuel screw setting is, I know the stock main is 122 correct? thanks

[plkmonster2]

Run a 128 with a lid on. 130 with it off. Unscrew your mixture screw 1/2 turn. If it still pops on decel, you need a 40 or 42 pilot.

[fastmofo]

alright, thanks, you mean 1/2 turn out from all the way in on the air screw right?

thanks

[300exOH]

Originally posted by fastmofo
alright, thanks, you mean 1/2 turn out from all the way in on the air screw right?

thanks

I think he means an additional 1/2 turn out from stock. I run mine at about 2 1/2 turns out from lightly seated. I am also running a 42 pilot jet. The larger pilot helps a bunch with cold startup. I don't even need to use the choke when she's cold.:bandit:

[miken]

A 300ex stock is 122 main, 38 Pilot. My fuel screw is set at 1.5 to 2 turns from seated, and I think thats stock setting.
Mike -

[fastmofo]

well, checked the plug, was running lean, dug into the carb, had a 142 main, air screw 2 turns out, and needles clip 1 from the top. put the needle back to 3rd clip and going to try that.

Doesnt a 142 sound big? i dont know if it matters too much, but i live in minnesota, and its been about 55-60 degrees here

[zoe17]

I have a 2002 ex and I run a 168 main.I run no lid and a T-4 pipe, with a few mods. So run as big as you can checking the plug for cardboard brown color is how I did mine.

Good luck

[Aceman]

Originally posted by zoe17
I have a 2002 ex and I run a 168 main.


Is that a Dyno Jet or a Keihin jet? I have a 330 kit with a 132 keihin main jet at sea level and it's right on.

[bradley300]

what throttle setting i it popping at? that is more important to know than just while its deaccelerating. i'm sure you know pilot is low or no throttle, needle is about a 1/4 to 3/4 and main is 3/4 up. sounds to me, assuming you deacelrate with no throttle at all that your pilot is too lean

[fastmofo]

its with no throttle, should i try 1 size bigger pilot jet? the pilot jet is stock, i talked to the previous owner

[400exdad]

The 40 or 42 pilot will fix it. They are WAY to lean from the factory. Ours was really tough to start with the stock jetting. Main will have no effect on decel popping.

[fastmofo]

Ok, thanks guys!