need to know. going riding this saterday

[atvdreamer69]

i put a k&n filter and pre filter on my 08 400ex and a lexx mxc pipe, i know it needs to be rejetted but it seems to be running great right now, would i hurt anything riding on it this weekend before i jet it? and advice would be great, thanks

[Rkangel7]

I'm running the exact same setup. Lexx, K&N, and prefilter. At sea level I'm running a 150 main jet (stock is 148). That's just about right for my conditions, but your conditions may vary. Whether you'll be ok with stock jetting is hard to say. I've seen others running 152 or 155 main jets with similar mods as ours. But, it really seems to depend on the quad and riding conditions.

[atvdreamer69]

thanks Rkangel7, we could prolly use each other for advice down the road. i hope i dont mess aything up. it ran great when i took it for a spin in the woods today

[goldfish]

I've got the same setup, just the Lexx pipe and K&N filter. I am at about 900 feet elevation and running a 155 main. I took it out for the first time since installing the pipe last weekend and it was running like a champ.

[Rkangel7]

Anytime, atvdreamer.

Goldfish reminds me of a good point. Jet sizing numbers vary between companies. Stock is Keihin. Mikuni and Dynojet make jets for the 400ex, too. But, their numbers are different for the same size jets.

[PaRedneckRiders]

i had a K@n air filter and a white bros e-series on mine and i 148 was lean im going to put a 155 in it and that should do the trick but it all depends one where and how u ride
its one of those trail and error things but i would guess somewhere around a 150 or 155 should work for u