jetting for pro circuit t-4

[XCRacerwanab29]

Hey guys I bought my 400EX from a guy locally and he had already gotten a procircuit t-4 full system for it. He also jetted it with a k&n jetkit. I was just wondering if anybody knew the jetting numbers for this pipe at sea level and below.

Thanks

[cals400ex]

if he has dynojets in, i am probally not the man to help you. if he bought individual keihin jets, i can help. i would bet with the dynojets that you will need to be close to this:

3rd notch on needle with clip
146 dynojet


now, this is just a guess, i don't use the jet kits. i buy individual jets. i would also put in a 42 pilot jet unless your in warm climate year round.

[Butch]

I have just the T-4 Slip on and I run a 155 main jet and have yet to modify the pilot jet, but I'm thinking this would probably help my cold weather starting problems that I have(I live in Minnesota). The 155 Keihin works for me and its also what my buddy runs on his EX.

[cals400ex]

a 155 will be fine if you are using keihin jets. i think he mentioned he was using a jet kit. the jets in the kit come with a different numbering pattern than keihin jets. so a 150 keihin doesn't equal a 150 dynojet.

[Crawl69]

Mine runs the best with a stock 148 kehin jet and 3 turns out on the airscrew.

[Pappy]

try a 152 if using a khien jet...155 with the dyno jets(k&n kit)

[ratboy]

hey dude i live in kenner la and have the same set up. you should be fine with what he had in it. if you change to keihn jets use a 155. if you have any other questions email me. vanilla125rlc@cox.net:devil:

[YTZ250#1]

My 400 had a slip on T4 and K&N power kit.I am below 3000 feet
and ran a 170 main and a 52 piolit.I also have the 2 extra end caps for fine tuning to get more low end.I no longer have quad
(it was stolen) but I do have the end caps if anyone wants to buy them.Oh ya the air box lid was removed when runing that set up.

[ratboy]

yeah i have no jet kit just bought the keihn jets but also have no air box lid thing runs like a scalded dog its great. how much do you want for the end caps. have you ever used them and can you tell a difference when ou change them out?

[YTZ250#1]

I have tried both of them and seen some minnor increses of bottom end power.the one that came with the pipe worked best for racing,But the smaaler ones were better in the woods.They also make a little less noise.I would take $30 shiped for both and the spark arrester.

[ratboy]

i have a spark arrester mine came with the 2 in. end cap let me know i am very interested. do accept pay pal or tell me how you would want to do this