quick question plz reply

[400exfan19]

i have a 2004 yfz with aluminum pro exhaust and no lid. It is jetted correctly to that, if i choose to put a K+N filter instead of stock will i have to rejet?

[Flyin-Low]

Best to put this in the YFZ section..

But I doubt you will have to rejet, probably should bump it up a size though.

[416exfreak]

Theres a small chance that you might have to increase the main jet a size or so.

I doubt it.

Just put it on and see if it runs good.

As long as your plug doesnt look burnt, id say your ok.

[smr]

if you ride in dust at all get ready to rebuild your topend.

k&n is fine outwest but here in the east I would only run a foam filter.

[bwamos]

I run a UNI nowdays, but over 8 years of running a K&N filter on my ex, I never had any issues w/ excess dust entering the intake system.

Missouri is very dusty and has very fine dust particles as well.

you are increasing air flow, therefore you must increase fuel flow to keep the correct ratio...

[smr]

Originally posted by bwamos
I run a UNI nowdays, but over 8 years of running a K&N filter on my ex, I never had any issues w/ excess dust entering the intake system.

Missouri is very dusty and has very fine dust particles as well.

I don't think you would be able to pull that off on a 450.

[416exfreak]

Originally posted by smr
I don't think you would be able to pull that off on a 450.

An ICE (internal combustion engine) is an ICE no matter what its displacement is.

I dont see how 50 more cc's are gonna make a difference on what filter he uses. He may have to step up his main a size or two if he uses a K&N, but I dont see how using a K&N could be bad...or how he couldnt pull it off on a 450:huh :confused:

[400exfan19]

is it possible to use the main jets from a 660 on my yfz???

[Flyin-Low]

Originally posted by speedyquad
you are increasing air flow, therefore you must increase fuel flow to keep the correct ratio...

This air filter won't create THAT much more air flow than a stocker, and engines run best just on the border of lean.. So chances are that it will be fine unless the bike was already lean or right spot on.

[ohsobad_chevy]

Originally posted by Flyin-Low
..........and engines run best just on the border of lean.. So chances are that it will be fine unless the bike was already lean or right spot on.

Engines make their peak power when they are a tad lean, but not enough to justify it. If anything, you should be a little tiny bit rich, it will help keep the temp down a little bit and you will not have to worry about damage to the engine.

You should always re-jet your quad anytime the A/F ratio has been altered. Do some plug chops and make sure you got it dialed in, you will know when it is happy. ;)

[400exfan19]

so it wouldnt hurt to just put the K+N in and then bump the main jet up one? then check the plug to see if it looks ok? how long do i wait before i check it

[ohsobad_chevy]

Ya, I would bump your main up just one size. Its hard to say, but you will most likely need to change your pilot as well. Check out the jetting thread, there is lots of awesome information. You will be able to tell when your quad is jetted correctly. It will rev out smoothly and you will feel it.