42 pilot jet

[HondaChris]

Ok, I have learned from on here that a 42 pilot jet will cure the cold weather starting problem with a 400EX. But, does it affect anything else in the summer months? Or anything else anytime else for that matter. I am asking this because I am taking my quad in this week to get re-jetted for a FMF PowerCore4, and FMF recommends a 40 pilot to be installed. If a 42 is the way to go, than I would have the dealer do a 42 instead.

[Dune Surfer]

My sugestion would be to learn to do the jetting yourself. That way when you ride differant elevations you will know how to do it:D No need to pay to have a pipe and jetting done, anyone can do that themselves.

i am usin a 45 pilot and i dont have ne probs in the cold

[White_Knuckles]

Wow a 45 is FAT (large). The question posed is for summer ridding so 40-42 is in there. Most of these mods include air flow i.e. airbox mods high flow filter etc. If you are not increasing air flow the smaller pilot would be my first pick.

Dune Surfer is right it's pretty straight forward, doing it yourself has a payoff that you can tweak settings in the future. Don't pay the "stealer" for questionable quality service on easy tasks my 14 year old does his own jetting and pipe mounting.

[Dune Surfer]

Originally posted by White_Knuckles
Wow a 45 is FAT (large). The question posed is for summer ridding so 40-42 is in there. Most of these mods include air flow i.e. airbox mods high flow filter etc. If you are not increasing air flow the smaller pilot would be my first pick.

Dune Surfer is right it's pretty straight forward, doing it yourself has a payoff that you can tweak settings in the future. Don't pay the "stealer" for questionable quality service on easy tasks my 14 year old does his own jetting and pipe mounting.

Believe me now?
Do a search for a post called Installing a K&N power kit. It walks you through jetting with pics and instructions. It's how I learned.:D With the money you save you can buy mods:D :D

how is a 45 too big...mine runs perfecto with a 45 and 155 with sparks stuff

[White_Knuckles]

A 45 may not be too big for your mods and altitude. The average is 40-42 for high air flow mods (like yours), if he has stock lid etc. a 45 would be rich even at sea level but could be dialed by cranking out the fuel screw 1-1.5 turns instead of the average 2-2.5. It's not bad advice just not the average. Some guys yank out the choke and a fat idle circuit may keep the thing running with cold starts. So... jet voodoo is subjective to different applications.

Peace :)

[Colby@C&DRacing]

a 45 pilot works great in some bikes depending on the mods. When I still had a stock carb on our 416 I used a 45 pilot and it ran great even in the summer when it was hot out.:)