What main jet size?

[Mx_523]

I have a 300ex with a Curtis Sparks pipe and stock filter with the air box cover on. My elevation is around 1700 feet. What do you recommend my main jet to be? 135?
Thanks.

[Mx_523]

Anyone please?

[RiderTRX400ex]

what is stock jet size..?

[Mx_523]

Not sure, but I need a anwser quick. I'm going to be buying these parts soon.

[300ex_#387]

Well I run a full system, k&n, and no airbox lid and I only run a 130....135 might be a little to big, but I would get a couple more answers before you take my word for it.

[300ex_#387]

Ohh and the stock jet is 122 I believe.

[LT250RMan]

start with stock size jet and work your way up or down in sizes of jets and just keep checking your plug to see how lean or rich its running, the plug color should be a chocolate brown when its jetted good

[bwamos]

135 main on the Sparks X-4 would be for aftermarket filter and no lid.


I would start with a 128 Keihin Main.

[RiderTRX400ex]

128 sounds good