Jet size for PC T4/K&N Stock Air Box

[wchughes5]

I know it may have been asked before, but I couldn't find a good answer that suited my situation. I was just wondering a good jet set up to use with a PC t-4 slip on and a K&N with a stock airbox with the lid on. Thanks!

[Buffalo400]

152 keihein will be just fine

[04'400ex'er]

I would try a 155 to start. Might be a little lean but shouldnt need more than a 158. 152 seems a little lean. I ran a 155 with K&N, lid off, and removed spark arrestor on stock pipe. Might want to jump up to a 40 pilot or 42 at the most. I would buy those jets and you will be just fine. Also, Call procircuit and start off where they tell you. but what they tell you will be with the stock pipe so compensate for the K&N accordingly.

[400exrider707]

A 152 sounds right. Needle clip down one notch (4 down total), and a 40 pilot should get you close. I have a slip-on, uni w/o lid, stage 1 cam, 11:1 piston and I run a 155 with a 42 pilot. I tried 160 main and 45 pilot and it puffed black smoke.

[04'400ex'er]

Originally posted by 400exrider707
A 152 sounds right. Needle clip down one notch (4 down total), and a 40 pilot should get you close. I have a slip-on, uni w/o lid, stage 1 cam, 11:1 piston and I run a 155 with a 42 pilot. I tried 160 main and 45 pilot and it puffed black smoke. Yall must be at a different elevation cuz with my HMF no lid and K&N I run a 45 pilot (42 backfires like hell) and a 160 main. And Im gonna try and richen up the main a little.

[400exrider707]

Originally posted by 04'400ex'er
Yall must be at a different elevation cuz with my HMF no lid and K&N I run a 45 pilot (42 backfires like hell) and a 160 main. And Im gonna try and richen up the main a little.

Probably and every engine is different. I ran a 155 with just a slip on, K&N, and no lid and it puffed black smoke.

[04'400ex'er]

Originally posted by 400exrider707
Probably and every engine is different. I ran a 155 with just a slip on, K&N, and no lid and it puffed black smoke. thats wat i ran with removed stock baffle and k&N and no lid and it ran great.

[400exrider707]

Yeah when I removed my lid and ran a K&N I ran stock jets and moved the needle clip down one position. It ran great. Obviously we are at two very different altitudes.

[wchughes5]

So a 152 and a 40 pilot with the needle down 1 should be good for me to run here in Florida?

[cals400ex]

if they are backfiring on deceleration, turn the fuel mixture screw out a little bit. you can actually get quite a bit of adjustment out of this screw. i can probably run anywhere from a 40-45 pilot jet as long as i mess with the fuel screw. i like to go a little larger on the pilot jet and turn the screw in. no really reason for it but i don't think you are "technically" supposed to go out farther than 3.0 turns out from lightly seated. however, most people do and don't have any problems.

in florida, a 152 and a 40 pilot jet should be fine.

[duke416ex]

I ran t4 slip on, k&n, no lid and ported header with a 158. Ran perfect.