What causes this??

[XxXx~FLY~xXxX]

when i take on my 4wheeler its fine but when i'm just going @ a normal constant speed it misses bad, but only when i am going constant @ one speed. i think it s because i need to jet it~ i have a k&n,few holes drilled in the airbox lid,and piped. i just got a new spark plug so its not that. do you think its my jetting?? please help.

chris

[airheadedduner]

Did it do it after you added the mods?? Everytime you change anything to do with intake or exhaust flow you HAVE to change or at least check your jetting.

[XxXx~FLY~xXxX]

how do u check your jetting?? and does jetting add any power??

thanx,chris

[tumbler440Ex]

it could be old gas or water in the gas so bad gas maybe
or it could your cdi i had that problem when i had a 400ex but mine was miss at the top of each gear then the cdi went in it.
but just my biff i could be way off. and theres no way of checken your cdi i could be way off to so dont hold me against it
might be jets too ...

[XxXx~FLY~xXxX]

o and about doing it before the mods i don't no! b/c before i got my pipe i always went through the gears real fast and never stayed a constant speed, but now its way to loud to do that!

[XxXx~FLY~xXxX]

well i guess bad gas could be it but i've had experience with bad gas before and the 4 wheeler did'nt run @ all. but still it could be that.( HOW CAN YOU TELL IF UR RUNNING THE WRONG JETS)???
thanx
chris

[nakomis0]

I know what your talking about with the sputter at a constant speed. Its a jetting problem.

Good luck trying to get it jetted right. Try something simple first , like go 1 size larger on your main jet.

[Rastus]

Its jetting. If you have added that much, and havent re-jetted, im sure your runnin REALLY lean.How long have you been ridin it like this?If its very long,it could be ugly.

[skemp]

Yep, when you change the intake or exhaust, you absolutely positively HAVE to rejet, like stated earlier. Unless you have a fat wallet and don't mind downtime for repairs. With those mods, I would say put in a 40 pilot jet, raise the needle one notch, and put in a 155 or 160 main (I would run the 160 to be safe.) Until you change the jets, I honestly wouldn't ride it. You could have already caused some damage to the rings and cylinder walls, but you are probably still okay.

[airheadedduner]

Definatly jetting then. You added all that stuff to flow more air, but oh-no you didn't rejet. That means that you are not getting enough fuel. I think a proper burn is something like 14.7 parts air to one part fuel. You probly actully lost power. Check your plug it should be a light brown if jetted corectly. White is lean, black/dark is rich. Jet only one circut at a time. What pipe filter and other mods.. are you running? If I knew that I could help a little more. Running your machine lean is doing a ton of internal damage. With a pipe, filter you probly need to go 3-5 sizes bigger on the main and 1-3 sizes bigger on the pilot. I don't think you will need to change the needle but consider it.
Air screw-Idle to just off idle. Always between 1-2 turns out from seated.
Pilot-effects off idle to 1/4 throttle
Needle/clip position-effects 1/4 to 3/4
Main-3/4 to full
Now there are other things like needle taper and stuff but noone but a pro has to worry about that most the time. Hope this helps.

[XxXx~FLY~xXxX]

man i have been ridin it with the white brothers pipe for bout 3 months with out jetting! and i just put the filter and drilled the airbox lid and i ordered the dynojet kit but it was for another 4 wheeler and i had to send it back! man i hope everything is alright! ok so do u think i could ride it about 2 miles down the ride to o fishing on it r is that to much?? i really appreciate everything ya'll have told me. also will i gain anymore power with the jets cause with all these mods i haven't gained that much!!

thanx
chris

[skemp]

When you rejet, you will definitely notice an increase in power. If you want to keep riding it, put the stock filter back on, and put the airbox lid back on. It will richen it up a bit so it will be safer, but try to get it jetted ASAP.