DOES ANYBODY KNOW WHAT SIZE JETS K&N USES ON A 400 EX WITH A WB-E-SERIES PIPE AND K&N AIR FILTER
THANKS

 

The jets that come with the Dynojet don't correspond to stock jet sizes. In other words, the Dynojet I run in my 400ex is the 142 although the instructions called for the 146. The 146 ran too rich. Don't have any idea what stock jet this would be.

The kit is not expensive,$60 or so and I would recommend it.

Made it run much crisper on the low end but I think it is still lacking on top end. That may be my pipe (FMF Powercore IV). Maybe your pipe will be better on the top end. I would like to see a pipe shootout from one of the Mags..

 

I am running a 165..

 

THANKS I JUST ORDERED THE JET KIT AND FILTER TODAY WORKED ON THE THROTTLE CABLE ADJUSTMENT LAST NIGHT GOT APPROX 1/16 MORE PULL IM CURRENTLY RUNNING 100 OCTAINE FUEL AND A WB E PIPE WITH A STOCK FILTER AND JET AND GOT DUSTED BY A 400 WITH K&N FILTER AND JET KIT.IM ALSO LOOKING INTO WB IGNITION AND 16 TOOTH FRONT SPROCKET.

 

THANKS I JUST ORDERED THE JET KIT AND FILTER TODAY WORKED ON THE THROTTLE CABLE ADJUSTMENT LAST NIGHT GOT APPROX 1/16 MORE PULL IM CURRENTLY RUNNING 100 OCTAINE FUEL AND A WB E PIPE WITH A STOCK FILTER AND JET AND GOT DUSTED BY A 400 WITH K&N FILTER AND JET KIT.IM ALSO LOOKING INTO WB IGNITION AND 16 TOOTH FRONT SPROCKET.

 

wideopen,

You don't need to run 100 octane gas. With the few mods you have, you won't gain performance and it may actually be the cause of a less-modified 400EX beating you. Stick with premium pump gas, 92 or 93 octane.

 

My 400EX has the K&N Dyno jet kit and filter, I installed a 14 tooth front sprocket for better climbing power. It doesn't run any better using premium gas, so I stick with 87 octane.

 

So is that the deal with the FMF header pipe ?
Damn I ordered this thing from Chaparral about 5 weeks ago. All those clowns tell me is, " Should be here any day now". I'm almost ready to cancell my order and get that pipe from Noleen. Any info on a shoot out between these two ???

Getting air in Southern Cal !!!!!!

 

Ninja... Is that the header pipe for the 400? The PowerBomb? I have had mine on order for 3 months straight from FMF. I have talked on the phone with FMF hella times. The issue is that the are still manufacturing them. The 400 ver shold come out on the first. I just talked to them this morning and they said all they are waiting for is a bracket fitting.. The YZ400 header has already been released.

 

87 Octane!!! That is bad for the valves... That is y you get a knocking noise in your car sometimes. I run straight 92 in all my vehicles. Didn't you look in your manual where it says run 92 octane????