I am putting a 440 kit in my 2002 400ex and i think i will need to rejet it but im not sure, i have a k & N intake now and stock exhaust but will be high flow exhaust by summer, i was wondering if anyone has any ideas of how to jet it or what to do, thanks

 

The easiest way to jet, is by the drivibility symptoms. The way the motor acts, will tell you whether its rich or lean. In your case, using stock jetting, wont be rich, so just focus on the symptoms of lean in each range of jetting.
Heres a good article on jetting, which also desribes the symptoms of lean and rich
http://www.motorcyclecruiser.c...carburetion/index.html

 

If you're running a lid on your airbox then your K&N, 440 kit, or exhaust won't give you any more noticable power, and in turn won't do a thing to your jetting. The biggest restriction on the 400ex is the tiny peehole snorkel that supplies air into the airbox. I've gone through this with mine. Unfortunately that airbox lid has to go, and unless you do something creative afterwards, will cause your filter to get real dusty and you can forget riding through water and even snow. The K&N filter lid helps in all but snow (it will clog). I actually made some foam seals along the subframe rails and across the back of the airbox to keep the tires from throwing debris into the airbox.
With that being said, once you chuck the restrictive lid, your 440 will take at least a 200 main jet, depending on your altitude. Here in New Jersey I run a 215 main with the setup listed in my profile, but have to go to a 160 if I want to put on the lid to make it seaworthy.

 

Well mr bandit what your going to need to do first is throw your damn 400 away it sucks and it is slow.. you probably wouldnt have so many problems with it if you wouldnt have bought it from such a muckid.. second get the thing out of my corncrib before i burn it. then u should give me the megamax.. ribitibeebees

 

haha dan...what the **** okay...first of all ......frickin muckid second of all, the megamax is mine...you have your own that sux...third my 400 is gonna befaster than the ds cause it doenst run, the raptor because it blows ***, your 400 because its megamax sounds like some fatass takin a ****, and the 450 because your *** will prolly flip it off the start, or get stuck in a snow drift, and wtf dan you said i could put it in your corncrib, you are lucky to have it there...it pretty much adds value to you truck...haha but serisouly get your own megamax......moga

 

haha dan lets make another video

 

I have a 440 stage 2 hotcam with the choke removed.Im running a 158 main,with a 42 pilot jet.I have a Pro Circuit exhaust.I would really recommend the UNI filter if you are gonna take the lid off the airbox.