jetting-HELP!

[LT250Racer609]

ok i removed the spark arrestor from the stock exhaust and i am running it the same as i would with the HRC kit but i bought a K and N filter w/ an outer wear and i plan on removing the stock air box lid...right now with the spark arrestor removed and the stock exhaust gutted with only the end cap...i am running a 125 main jet but i dont have the air filter on yet and still have the air box stock...when i put the K and N in w/ the outerwear and remove the lid...what should i up my main jet too?...people have told me to bring it to a 180 but i just want to make sure

[sulnz450r]

I have done the same thing and I put the 180 main in to see how it would run and as long as the air-box lid is off it will run great, mine did anyway, but I do not run without the lid so I had to go back down . I put in some inserts in the lid for more air 12 to be exact and that got me to a 155 main but still need more air for the 180. Will have to wait for a power lid I guess.

[LT250Racer609]

yah im removing the whole lid cause i just run MX tracks and my own track

[sulnz450r]

In that case you should be a ok !! hammer down !

[dodgeram]

I run the same setup and run a 175 main

[LT250Racer609]

u dont find a 175 to be too lean?

[sparky450AR]

Originally posted by LT250Racer609
u dont find a 175 to be too lean?

I have ran everything from a 160 to a 185, and I have found that a 170 delivers the best throttle response and all out power, this is what I run. A 175 also works VERY well. When I put in the 185, I could tell the jet was a little fat. This is with the airbox lid cut like an HRC, SA removed, and a UNI filter. The inside of my exhaust is white, and that is a sign of perfect jetting! Same with the spark plug. If your spark plug is black at all after rejetting then changing it, you are rich, and you arent getting max power.


With the airbox lid completely off, I would reccomend a 175, nothing more.

[LT250Racer609]

alright and do i mess around with the pilot jet? or just leave it on the stock setting...i put in a 175 main now

[ZRider400]

with baffle removed, lid removed, and u ni filter....i run a 170 main jet.

[jt911]

I use an air/fuel ratio meter. Perfect jetting all of the time!

[wvspeedfreak]

I am running a HMF slip on and a Twin Air filter with no lid and a 175 main.It runs excellent.

[ZRider400]

Originally posted by wvspeedfreak
I am running a HMF slip on and a Twin Air filter with no lid and a 175 main.It runs excellent.


did you change anything else like the needle or pilot???

i put a hmf on mine with uni /no lid...and a 180 main and it was lean.

[wvspeedfreak]

I left the needle and pilot stock.However,I dont have the HRC kit.My engine is completely stock internally.

[ZRider400]

Originally posted by wvspeedfreak
I left the needle and pilot stock.However,I dont have the HRC kit.My engine is completely stock internally.
ya i dont have a hrc kit either....i dont know why mine was so damn lean.

o well i'll figure it out eventually