Exhaust and k and n

[DE400EX]

I just put my exhaust on, dg header and pipe with a k and n and i didnt touch the jets, it fires right up and runs soooo much better...

Has anyone else done it with out touching there jets?

[Jared Coderre]

I don't know the altitude your in but I can tell you you will be lean and will result in problems. I suggest you at least put in a bigger main jet, A 165 for tha combo will be about right. If you think it's good now with a pipe and filter wait util it's jetted right!

Just offering some help, a lot of guys on here helped me out

[hornetgod13]

Change your main jet to a 158K, 160K, 162K and you will really see a difference. You are no doubt running lean. That's not good on the motor over the long hual. Putting a 40K or 42K pilot in wouldn't hurt either.
You can find jets at www.jetsrus.com

[DE400EX]

I have all the jets, a friend had a 400 ex and had them left over.

It runs great now. I will swap out the jets to see if it changes..

How can i tell if it is running lean?

[hornetgod13]

You need to install a new spark plug after you rejet and follow the "Plug Check" steps in the following link.

White=Lean
Black=Rich
Light Brown=Perfect

http://www.4strokes.com/tech/sparkplg.asp

[HondaSkidoo]

Originally posted by hornetgod13
You need to install a new spark plug after you rejet and follow the "Plug Check" steps in the following link.

White=Lean
Black=Rich
Light Brown=Perfect

http://www.4strokes.com/tech/sparkplg.asp

Great Link. Thanks

[DE400EX]

It was running rich before i put the filter on...

[hornetgod13]

Have you checked it since you put the exhaust on? You should be lean now. I know you have a DG header but, what kind of muffler do you have? What's the average temperature where you ride? What's your riding elevation. Is your airbox lid on or off? All those will effect your main jet size selection.

[DE400EX]

Its the DG oval light exhaust.

Im in delaware- 450' above sea level. Right now its around 45-50 outside. I will keep the lid on, some palces get pretty wet and im not tryin to blow up my motor. I think i will be swapping the whole exhaust for a full yosh system soon, my brother just puit his on and i like how you can change out the endcap for different dec. levels.

[hornetgod13]

152K or 155K will be a good start for a slip on and the airbox lid on. You'll want to go up a size or two for a full system.

[DE400EX]

I changed to a 42 pilot and a 160 main...

So far it seems to start better and i took it down out in the corn field and it lifts the front end up in 3rd gear now...

We are ridin on saturday so ill see what the plug looks like after that... So far so good. You guys were def right, after i changed the jets i was much happier.. :devil:

[Honda#4]

160 might be a tad rich but it's better than being lean. I'd say put in a 42 pilot 152 main and you should be about right.

[hornetgod13]

With you mods a 160K is rich. You will foul the plug eventually. I back it down to at least a 155K. You will notice a huge improvement on how it runs.

[Kaleigh]

here's a fast way to jet.. size up real big.. almost as big as you can go.. ride it at WOT.. if it bogs.. downsize on a jet.. repeat at WOT.. keep doing this til you find the jet that doesnt bog at WOT and thats probably the best jet onspot. i do it to everyone i ride with and everyones plugs look great.. nice and tan..

[Honda#4]

Kaleigh you are right, but it's not hard to ask a simple question on here that will get you close on jetting. But either way is totally fine with me.

[DE400EX]

I ran it wide open last night at it seemed fine.. No bogging or nothing.. I chased some deer across the corn field it was fun..

[DE400EX]

And after i rode it the plug was tan..