brandy new 400ex

[Arynock]

i just bought a 400ex, and i was wondering what would be some good start off mods to add to it, price would have to be under a grand, but i want some bang for my bucks, so i want some nice mods that will add some crazy power... if i get kits what all will i need? what would be some good mods and their prices, and what are the gains i'm looking from these mods, not just horsepower, lowend? highend? how much of a gain? noticeable?

t4 slipon with jets, uni air filter, definately shocks first! works are good, best bang for the buck

[Arynock]

well, i'm mostly try'n to get top speed and accel added, i know thats hard, but mine does like 70mph on the road atleast, i dont know i need to get a vehicle with a speedometer beside me, it flies, 400ex's have more than i thought they did, kinda scared me when i ripped it on the road in first gear and as soon as i popped into second without pulling up it pulled the front wheels right off the ground.... what are some good mods for putting into speed? what could be a good gearing to get into without losing all my accel.

16 front tooth sprocket...youll lose you wheelie power... get works shocks, you can only go so fast untill you have to turn :rolleyes:

[Arynock]

what is stock on the front tooth, damn man i dont want to lose my wheelie power... will i still be able to pull wheelies by standing on it and actually try'n, or will i lose that ability too.. ?
how much faster am i looking at going with a 16 tooth sprocket?

it will only make it more difficult to wheelie, you could prob still do it sitting down...the stock front tooth is a 15, with a 14 front tooth it helps wheelie so much easier but you lose abouyt 7 mph opn top, with the 16 you gain about 6 mph on top. id really suggest shocks first though with that grand, im sure alotta fellow exriders will back me up on this. :D

[Arynock]

what are some good shocks and what will they run me?
what will be the difference in the feel of the ride?
would putting a hotcam stage 2 or something in the stock engine give it more top end? or what? i'm try'n to find some motor mods to take speed up alot... 70 mph is fast, but i wanna go a bit faster but still have my wheelie abilities ^_^
shocks do sound good too!

[cals400ex]

you won't lose that much power with a 16tooth sprocket. however, you won't gain 6mph with it either. if i had to guess on a stock motor it would be more like 1mph. however, 1mph makes a difference when side by side on top end. if you were putting a stage 2 in it, get a higher compression piston. if you are leaving the stock piston in it, get the stage 1 or something equivalent. as far as shocks go, there are several ones that you can get. works would be an upgrade from stock while being a lot cheaper than some others but not quality as some others. axis and elka are two of the more expensive shocks.

[Arynock]

well what would it be good to go into after getting shocks?

[2001400ex]

I have a quick question, about two weeks ago I changed the oil in my quad...went out saw the air-filter and was like ah what the hell, might as well...I bought the UNI air filter, but I had a K&N in it when I bought it, which will give me the most performance? Since I saw you mentioned to get the T-4 and the UNI?

[sparks400]

u can get a nice pipe like a sparks for like 450 or lrd, but works shocks should be first, there a very good bang for the buck, if u want top sped change ur gearing around, remember high front sproket, and lower rear sproket. and then u will have about 200 more, so u can also get like, a hotcam, and ull have like 50 after that, u should save for some tires, or sparks carb mod, or a new carb like a fcr 39 or 41mm.

[Chanman420q]

Dont bother with works, there like blasters, u out grow them fast.

Best Bang for the buck is Elkas W/o Rezzys

elkas w/o rezzys will be about all of your money :rolleyes: $850.00

[sly400ex]

If you really want to speed it up, do a 416 kit w/ a hot cams stage 2...about 300 bucks, slip-another 200-250. Buy some used elkas off ebay or something for around 500 and your set. And your quad will pull a hella quicker!:devil:

[Arynock]

What all is needed for a 416 kit? peice by peice, price by price...
how much power gain am i looking at? will doing this remove my warranty, cuz i think i might have to wait till my warranty is out... just bought her a few days ago... haha..

yah this will definately void your warranty.... you can keep your warranty with new shocks.........slip-on maybe? i dont know :confused:

[PHIL_B54]

Originally posted by Arynock
mine does like 70mph on the road atleast,

64-65 mph tops when mine was stock

http://home.earthlink.net/~gellett/400ex.htm

play with the gearing on that link and it will tell you what it will do to mph. to get it a little closer i take off 1/2 of tire dia. because they arent 20" dia unless they have mondo pressure in them

[remlapr]

You obviously want to go faster first. This is what I suggest:

Buy a good slip on of your choice, the most popular are probably the T-4, E-Series, and HMF. Then buy either a K&N with outerwear or a UNI - there are plus and minus's to each, do some searches and you will find all the info you need. Put these on at the same time along with rejetting your carb - don't buy a "kit" just go buy some bigger pilot and main jets from a dealer for a couple of bucks each. Also, remove the airbox lid - or drill vent holes in it towards the back of the air box, again - do a seach and there are a ton of threads about air box mods. Next - send you carb to be bored out to 38mm and the choke removed - this is $125 - $175. That is about all you can do without going into the motor. These modes will make a big difference over stock and should only cost you about $500 max.

[luvmyex]

my question is... why do you want more top end?Are you just riding it on the road? If you ride trails you are hardly ever gonna max it out.Sand i can see wanting more top end but thats it! slip on, carb, filter and air box mods should make a big differance.If thats not enough for ya then bigger piston,and a cam.

[Arynock]

what is the max rpm on a stock 400ex? I ride on the road ALOT, i dont do much trail riding... i mean i do, but 5/6th the time its road, haha..

[bmw500hp]

Originally posted by remlapr
You obviously want to go faster first. This is what I suggest:

Buy a good slip on of your choice, the most popular are probably the T-4, E-Series, and HMF. Then buy either a K&N with outerwear or a UNI - there are plus and minus's to each, do some searches and you will find all the info you need. Put these on at the same time along with rejetting your carb - don't buy a "kit" just go buy some bigger pilot and main jets from a dealer for a couple of bucks each. Also, remove the airbox lid - or drill vent holes in it towards the back of the air box, again - do a seach and there are a ton of threads about air box mods. Next - send you carb to be bored out to 38mm and the choke removed - this is $125 - $175. That is about all you can do without going into the motor. These modes will make a big difference over stock and should only cost you about $500 max.

I am with remlapr...

You seem like you love the power so for you "more is better" and while your at it, why not enjoy the sound of your new quad..Here's what I would do if a new 400ex greeted me in my garage and the wallet overflowed at $1000.00

1 Used T-4, E, HMF, all great pipes (pay 100 to 125) for a nice "used" one!

2 Have a reputable mechanic address the carb as remlapr suggested. Boring is a performance enhancing option, Rejetting is a necessity.

3 Have your mechanic suggest air filtration and airbox upgrades

4 Keep visiting Exriders and take advantage of a deal on some good used shocks TCS, Works, Elka, Etc. You should be able to aquire these for +/- 500.00 if you work at it.

5 Try to find a used rebuilt rear shock for your quad..You should be able to do this for +/- 200 to 300 dollars. You may be luckhy enough to find both of these for sale from one owner. Rebuilding services are also popular. You may consider this for more accurate personalization.

6 Finally, do something to enhance the cooling of that new machine...30 to 40 dollars should be sufficient to purchase a set of aluminum air scoops..these not only look cool, but function to direct more air to the oil cooler and cylinder.

As remlapr said, kits are for kids...address each part on your own. Much of the fun of owning an ex is the comraderie of ownership found in these threads...

Finally change the oil often and run premium gas...:D

Welcome to some big fun! Your quad will now Handle awsome, Bark wicked and look and run cool :cool:

[Arynock]

thank you alot bmw500hp, i think i will stick with your advice, actually i dont know if i'm gonna be doing the modding now, or waiting till this winter, the only reason i have the extra money is saving up the whole year from working, i'm only gonna be turning 16 and my dad wanted to buy a 4wheeler and i conned him into a 400ex, now he wants to buy a rubicon, ugh... anywho... scared the hell outta me the first time i rode it, so i dont know if i'm gonna be able to handle adding more parts for more speed or accell when i still have to get use to it..

[sly400ex]

Originally posted by Arynock
scared the hell outta me the first time i rode it, so i dont know if i'm gonna be able to handle adding more parts for more speed or accell when i still have to get use to it..


I like to hear that about a stock 400, not that you're scared, but you were suprised by it's power. The 400, by any means, isn't this slow, obsolete machine that some people make it out to be:)

[Rick400ex]

I also have a stock 400ex. What will be the big difference if I put a front set of Elka shocks on the front ?
I weigh 260 so would these make me not get killed on landing when doing a jump ?:huh