400ex mod questions

[1Fun400EX]

i have a 2001 400ex with a few mods including fmf powerbomb header, fmf powercore4 pipe, k&n filter with outerwear, hinson racing clutch kit, edlebrock carb, dyno jet kit, lonestar racing twin row axle carrier and a few cosmetic parts such as race cut front plastics, pro taper bars, factory 909 grips, msr clutch lever and brake lever, white brothers graphics. my question is i have heard alot about people with 400ex's riding without there air box lid would this really do much for my quad considering what i have done to it?

[oleboy87]

yea everyone is going to tell you that it is better to ride with it off.. Ive ran both ways i didnt see a difference but then again yours has a little more mods than me soo it might help you out more than it would be but the riding i do i rather it on cause of all the stuff that ends up in the airbox...

[1Fun400EX]

yeah i kinda figured that when im on the tracks i ride i might take it off just to see if i feel a diffrence but when im on the trails im definatly going to keep it on. what do you think about the k&n air box lids good or bad?

[oleboy87]

yeaa but you might have to rejet if you take it off... and yea i like those lids but idk how well they keep stuff out... where we ride its alot of sandy soil soo when i would get home i would have like 2 -2 1/2 inches of sand in my air box and i know thats not good with a k&n filter soo i run the lid but what im getting at is idk if the K&n lid would keep all that out

[1Fun400EX]

yeah true. next question is it worth the money to get a high performance rev box and diffrent rectifyer and is there really much gain from it?

[oleboy87]

well i dont have an aftermarket rev box but plan on getting on in the future.. there was a thread a couple of days ago about the amr rev box and coil and they had positive things to say about it and they not that exspensive soo i think im going to give it a try.. but the main thing i like about em is that they claim a hotter spark! but idk about the rectifyer

[1Fun400EX]

yeah they do get a hotter spark and the spark curve through the rev is said to be diffrent to so im kinda wondering if the spark curve diffrence would help out on accelleration to gain the holeshot from the gate.

[oleboy87]

well a hotter spark cant hurt anything... it can only make it better ya know...i plan on getting the rev box and the coil.. and someone said in that thread that the coil help with the bog when taking off soo idk

[1Fun400EX]

anyones thoughts about air scoops for a 400ex?
what would be a good brand to go with and are they worth it?

[GPracer2500]

Originally posted by 1Fun400EX
...edlebrock carb, dyno jet kit....

Just so you know, those items are mutually exclusive. In other words, if you have one you can't have the other.

[1Fun400EX]

yeah sorry i had the dyno jet before i bought the carb

[maxfior]

Originally posted by 1Fun400EX
my question is i have heard alot about people with 400ex's riding without there air box lid would this really do much for my quad considering what i have done to it?

You can see the junk on my EX in my sig, but with a pipe, pre-filtered box and proper jet, I noticed quite an improvment in performance on my EX. I think you should give it a try but to get the full potential you will need to bump up main and pilot jet sizes... Don't know much about your carb, so you'd have to find out what's in it to begin with. Just my $0.02

Max

[oleboy87]

again i dont have any but everyone on this site is going to suggest tinners... try a search and you going to find them

[hornetgod13]

In my opinion, air scoops are worth the time and money spent to install them. Any added air flow over the engine is only going to improve the air cooling process. Tinner Scoops are nice but, my personal favorite scoops are made by www.metalmasterfabrication.com
The looks, construction, black or polished choice, and ease of install make them well worth the $45.00 you'll spend.

[1Fun400EX]

those look pretty nice i was thinking about getting a set of OMF air scoops. does anyone have a set if so how do you like them and any pics of your quad with them?