had problems after putting on an fmf 4.1 system. had it fixed for a while after i jetted and put in a twin air filter. now it will only run on prime, any ideas what would cause that?

i have a dynojet kit. 150 main. needle on 3rd notch. mixture screw 3 1/2 turns out.

it was fine for about 3 rides. then last time i went it bogged out and died on me so i kept trying to start it and it wouldnt. then i put it on prime and it ran so i tried putting it back to on and it died out again.

 

I have seen prime on atvs before but never really knew what prime does.Do you know exactly what it does to the fuel and engine?

 

You have a vaccum leak somewhere. In the on or reserve position the gas is sucked into the carb via engine vaccum. On prime it flows free straight from the tank to the carb. That's why it runs fine on prime.

It won't hurt anything to run it on prime. Just make sure you turn the petcock to on or reserve when you haul the quad on a trailer or truck, otherwise gas could overflow from the carb.

 

Yeah, if my Z sits for awhile without starting it, I have to put it on "prime" for it to start. Half the time I forget to put it on "run" and ride it on "prime" and never had any problems.
Nice pic of the wife there CATman [img]i/expressions/face-icon-small-smile.gif[/img]

 

its weird tho. it only does it sometimes. like i rode today and it was fine on the on position. only probably i had today was it bogs out when i dont rev the gear out before i go into the next one.

anyone know what that means? must be a a jetting problem, but does anyone know if it means im to lean or to rich?