filter and jetting ??????

[erichsen18]

alright, first off i need to buy a new air filter. The question is i was told not to buy a K&N because they let too much dirt through. i was told to get a UNI air filter. The question is, are the UNI ones better than K&N??? And the question about jetting, My 2002 400ex is all stock and im going to get the air filter and i was thinking about the jet kit, but would the jet kit do me any good since i dont have any other mods like a pipe or anything? I was hearing that puttin a 48?(i think) pilot jet makes it idle better. B.c mine is hard idling.

basically the questions are:
1)should i get a UNI filter or a K&N
2)would a jet kit do me any good on a stock 400ex

[JOEX]

I have a K&N filter and earlier this year I was riding in a fairly dusty area. Afterward I removed the filter and noticed a fine layer of dust on the intake boot. I rubbed it between my fingers and couldn't feel anything so I don't think there was any real damage done. But it was disheartening to know somethingwent by.
Personally I don't think the average rider will notice any performance difference between the two.
When I buy a new filter I thoinki'll be getting a foam type.

Don't waste your money on the jet kit. Just buy a few individual jets from either your local dealer or C&D Racing and go from there.

A 48 pilot is a bit big, go with a 40 or 42 and you should be fine.

Joe

[erichsen18]

alright thanks joe,

im goin to get the uni filter than b.c it is a foam type one. and about those jets, if i get the 42 pilot what size shoudl i get for the main? im kinda new to the performance part of this quad so ill need some help. would i notice a difference in power with these jets and filter with nothin else or no? when i get these jets and go to put them in what all would i need to do?

1. take out the old jets
2. put in the new ones
3. would i have to screw with the little pin thing in there?
4. would i have to mess with the air/fuel screw or no?
5. anything else?

[JOEX]

If you are just putting in an air filter a 150 or 152 main should be fine. If you are adding an aftermarket pipe go with a 155.
I bought mine used with the filter, e-series and 150 main so I can't compare to stock. I have rode a stock 400 but not enough to give an honest comparison on the two. But I belive you will feel a much better throttle response.

Changing the main jet is very simple:
Turn off the fuel
17mm socket to remove the carb bowl bolt
6mm socket to remove the main jet
reverse to replace.

The pilot is a little more involved but still very simple with a repair manual.

Joe

[erichsen18]

thanks alot Joex, you have been big help. Any suggestions for a pipe???

[chrisp333]

pro circut t4 full system

[erichsen18]

one more question....how much are individual jets from a dealer?

[JOEX]

Glad to help:) I'm happy with my WB e-series. It is starting to leak around the front rivets though.....time for some new packing....

Joe

[chrisp333]

theres a good chance if you bought the bike there theyll just give you one. if you know what one you want.

get to know a salesman theyre usually pretty cool about that stuff.

only my experience

[cals400ex]

as far as pipes go, it depends if a quite pipe, adjustable pipe, slip on or complete system(includes headers). for all out power, an engine builders pipe would be best. examples are curtis sparks, lrd, ct etc. however, these pipes are not adjustable with discs and are quite loud. other pipes like supertrap and white brothers are adjustable for different sound levels and will give a tiny bit less performance usually. as far as jetting goes, bigger does not always mean better. if your just putting a filter on, i would not change out the stock main jet in the summer months. in the winter months, going up one size might work better for you due to the colder more dense air. the stock mainjet is a 148. only go up to a 150. i think if you go up bigger than that you will have less performance than stock because you will be too rich. i would leave the needle and clip in the factory position. a 42 pilot jet should work just fine for you. you will probally only need to go out 2.25 turns or so on the fuel skrew with the 42 pilot in. good luck

the mainjet and pilot jet should cost less than $12 for one main and one pilot jet.