With no lid I'd go 160. With lid 152 or 155. Also don't forget turn air/fuel screw all the way in then take it 3 turns out. That will cure alot of it. But, STILL CHANGE JET!!

 

i ride with lid and i put a 150 in it would that be fine or do i need a 152 what makes it have better lower end 152 or 155 and what if i didnt turn it out sorry im new

 

If your not getting enough fuel it will run lean and burn up your engine. If you didn't mess with the screw it needs to be done. There again you will not allow enough fuel in and burn up the engine. It will increase performance all around because, currently your just supplying enough fuel for the engine.

It's easy to adjust the fuel screw and it will effect how low end runs. Here is a pic of it. DynoJet Sheet

Looking up this chart made me think. I believe I have mistaken. I always think of DJ being bigger numbers because, they use different measurements for jet sizes but, they aren't. With that in mind they recommend a DJ146 main with lid on and aftermarket exhaust. That's a 160 Kehien jet! I believe I would jump up to that. A 150 is just not much of a jump for that exhaust. I don't think your getting enough fuel.

 

so u still think i need a 152 or the 150 should be fine? or 155 lol im sooo lost... i just dont wana burn up my mottor but i want it to be better then it was stock thats why i put the exhoust on in the first place i also have uni filter if that matters...

 

i thought if my quad was bogging that ment it was to rich not lean the site that i got seen the resolts on the pipe said they had a 138 main jet in it could i just go to that inted of adjusting the fule/air screw

 

You need a 160. I know I originally said 152 or 155 but, I was thinking backwards.

And 3 turns out on fuel screw. That will cure the popping on deceleration.

 

thats just it dosent pop just when i hit the gas hard to pop a wheelie it bogs and falls on its face and a 160 is one hell of a jump man that would be 2 much full wouldent it and are we talkin about 2 diffrent makeers of jets. did u go though this with your 400ex?

 

A Dynojet 138 is a Keihein (what you have) 150. Recommended for 3000 to 6000 feet. So if your at that range you may get away with it. But still need adjust the fuel screw. It's right on the side of the carb and easy to do.

 

I had a 160 with lid off and went up to a 170 dyno jet which is like a 190 kehien. May adjust the fuel screw and see how i acts. It does affect idle a bit.

 

lol ive never done anything like this sept to a 2 stroke 250r but i just changed jets in that. umm it came stock with a 148 i put that back in my quad is all torn apart now. im in western PA idk how high that is are we talkin about feet above sea level. i think i have keihenin. im prob pissin u off im sorry i just have no idea what im doin lol