Pipe recommendations for this setup?

[NewRider]

Im new to this site and realise that this subject has probably been beaten to death.. hehe But figured maybe I could get some fitting suggestions with the equipment I already have. Ive been out of riding for about 10 yrs and then it was dirt bikes not 4wheelers.

Ok... what I have is a 99 400EX ... purchased it off a fellow who decided to get back into bikes. Its standard bore with a JE 10.8 piston, WB race cam, WB cdi box, K&N filter with Outerwear.

I know the current jetting is far from optimal in order to prevent backfire with the stock pipe... I do have a jet kit to take care of that once the exhaust problem is taken care of though.

For now (money kinda tight after buying the 400) , I am just looking to get a slip on... not the pipes as well. So any ideas on what slip on to get with the items listed?

Thanks in advance for any help :)

Anything will give you more power over stock,,if you want a loud pipe look at engine builders pipes,,CT, sparks, TCracing. If your lookin for just a little more umph without all the noise,,look at WB, FMF, BILLS, HMF<--been hearin good things about them lately. Most of the pipes listed are gonna give around the same power increase maybe 1 or 2 more hear or there but probably not much seat of the pants difference. I"d loose the WB cdi too,,cuz it will make the sucka hard to start. Go ahead and modify the stock airbox too if ya want a little more power..good luck.

[NewRider]

Thanks Rico,

Noise is not a concern... be it quiet or loud. Just something with slight increase in performance and allows me to rejet a little without the backfiring :rolleyes:

Yeah... it is definitely hard starting... even on these few nice days of Indiana weather its been rough.

Are there any links or old threads I should look at for the modification of the airbox?

Thanks again :)

Well I'm just across the pond from you in Lou, KY. Yeah we have had nice weather,,get your stock CDI back from the guy if you haven't already and put it on,,sell the other. end of story. It's been a debate out here on whether the WB CDI helps and in dyno runs the 400ex quits makin power past 9,000 RPM's or something close to that so you don't need the extry 1,200 RPM's,,plus you can't start your quad with it. I had one and sold it,,noticed no power difference on or off.

YOu can either take your airbox lid off or drill holes in it,,this will help a bunch over running with a lid,,I run 7 - 2 inch holes in mine.

Once you get your slip on pipe here's what you need to do to make the bike run better and have good power.

You'll need a 160 -165 main jet for your elevation, should take care of the backfiring.

a 40 or 42 pilot jet,,makes startin the beast real easy.

[NewRider]

Thanks again for the info Rico,

I have the stock CDI box, so Ill put it back on and try that. And as for the airbox, it had a bunch of holes put in it, he had covered them with black tape. Guess I'll take the tape off then huh? ;)

Thanks :D

[Blackguywithouta400]

Before I made engine and exhaust mods to my quad I did some jetting changes, which made a world of difference. First I would get a base line for your jetting I would check the needle clip position right now. I would take it and move it to the 2nd clip up from the sharp tip of the needle, this will add more middle throttle position fuel. Most full systems require this change and so did my bike after opening up the air box and adding a K&N Filter. Then I would look at my main jet I think you should be around a 155 or 160 stock jet, Not a Dyno Jet or K&N Jet Kit size because they are larger numbered jets. This should prove to be very close jetting. If this doesn’t work for you let us know im sure we can get this thing jetted correctly.:devil