2002 Honda 400ex

Greetings,

I need some assistance. I just purchased a 2002 400ex about a month ago and am looking into some aftermarket mods. I have about $500 +- to spend. I think I want to go with POWER MODS, to keep up with the other guys.

A friend bought his at the same time as I did and added the K & N Power Kit and it seemed to make a big difference, atleast in the sound, so that is probably on the list.

I have about 30 hours or so on it now and just changed the oil & oil filter, are there any other things I should do to it or look for? I read something about checking that throttle adjustment, but can't find the post, so info on that would be appreciated also.


Thanks in advance,

[VegasEx'r]

Get the filter & an Outerwears, too. Either get rid of the air box lid, or drill some holes in it to get more air. I wouldn't buy a jet kit because you can buy individual jets for less cash. Buy some mains in the 155-165 area, and you could pick up a 40 & 42 pilot as well. One free mod you can make is to remove the choke (if you do, put in the 42 pilot). I think that the $30 you'd spend for an advance key (15 for the key & 15ish for a new gasket) is well worth it. Then get an exhaust. If you want, you can grind off the welds inside the stock header & use it (I haven't done that, but I have heard good things about it.), or you can but a complete system (the complete system w/ all this other stuff will probably put you just over $500). as far as which exhaust to buy? There are a ton to choose from, and you'll have to research that. Engine builders buils the best pipes, and the Yoshi & WB pipes are good, too. I can tell you that I am happy with my Big Gun exhaust. It is built more for top end, and it works well. Throttle adjustment is easy. You should be able to push the throttle about 1/4" before it begins to tension up. Just pul the dust boot off of the cable & use the adjuster to take out any extra slack in the cable.

Hope this helps.

[Moto92]

Id say for starters get yourself a good pipe and a set of nerf bars

[Deathbringer]

I got mine last year and put the WB E series pipe on it..
Moded the air box
WB rev box
K&N power kit..that will give you the Dyno jets and needle to put in your carb....and NO its not the same as going and buying larger jets so don't believe it for a second.. and you dont have to change the pilot jet at all.... that is just a bandaid for not knowing how to adjust the clip on the needle... the whole thing will cost you a little less then you are talking about ($500)
The whole project will take you about 2 1/2 hours to do and will be the biggest bang for you bucks you will ever spend. Oh and by the way the part they leave out on putting the pipe on..yeah you have to pull the air box so do the pipe at the same time you are doing the mods on the carb.

WB pipe $230
WB rev box $110
Powerkit $110

Anyway that is what I would and have done....hope it helps you.

[Dave400ex]

I would get a better Air Filter Setup and Pipe. Here`s what I have:
TC Pipe
K&N Air Filter with Outerwear
150 Main and 42 Pilot

I really like the Power it added. If you get a Pipe, go with a Engine Builders Pipe. They seem to add more Power.

[sly400ex]

Warriorman....You don't think your runnin a little to lean with that 150 main, seems a little to small!?!

[Dave400ex]

No because I had Jason Orr from Orr Motorsports check the Jetting and he put a 150 Main in instead of a 155. He said it is Running better now. I have a 42 Pilot too.

[yellowrider]

WB pipe $230
WB rev box $110
Powerkit $110

Anyway that is what I would and have done....hope it helps you.


__________________

rev limiter sucks though it out dude on a 400ex has one and he said he cant feel any difference between stock and his new rev limiter.. i would not get one...

power kit are you crazy 110!!! just buy some jets
wb pipe ?? i had one on my 300ex but also i had big mud tires to so i really cant tell you how much of a difference it was..
i would not get another pipe with disk.. i had a little promblem with mine
:( if any of you all remember that .. .. ..

[JabberJaw]

Make sure you check the valves...

Bwilliams,,you need to adjust your valves,,,,today..:D Then add the other mods..

Thanks For All The imput :)

I think I will go with:

1) WB Slip on Exhaust
2) WB Rev Limiter
3) K & N Power Kit

One of you recommended adjusting the valves, is this something thay can be done easily or should I take it to the dealer to have done?

Thanks,

[Moto92]

valve adjust is in the tech section here. Its pretty easy as long as you have some mechanical skills.

Since u have a nice amount of money to spend i would defenately buy myself a nice exhaust system air filter and i would jet it to get some speed and horse out of it

[Dave400ex]

Don`t get a Rev Limiter. Just get a Pipe and K&N Power Kit.

[JustRace]

Heres the deal with the rev limiter. Its worthless on a stock motor. The only time that it is worth having is when you change to a more aggresive cam that will allow the motor to create power at higher rpms. The stock motor will have no more power with the added 1200 rpms than it will at the stock limiter. For example on cams. The white brothers track cam is a cam that is built to add more to the top end so you get the rev limiter to take advantage of the power that is added. Then theres the white brothers all around cam and that adds all the power from low to mid range so there is no need for a rev limiter. I just put the stock rev limiter back on my 440 and noticed no difference in power.

[Dave400ex]

I wouldn`t get a Rev Limiter on a 440 Motor. Duncan said there is no Reason. You should be Shifting before the Rev Limiter Kicks in. Keep the Stock one.

[Deathbringer]

I disagree with that.. I found that when I made the mods (k&n powerkit & wb pipe) that it was hard to start.. I added the rev box and it went away..so call me crazy but I think the package works great together... Do what you want but trust me you will like it if you do everything I said...

[Dave400ex]

Well that`s what Duncan said. I will never get a Rev Limiter. I always Shift Quick. Plus I Ride in the Woods and don`t Rev the Day Lights out of my 400ex. It`s your Choice, some Guys like them, some Guys don`t.

[RideRed04]

Should be easier to start with the stocker. It was easier to start becuase it was jetted right. Pilot jet a bandaid fix? No, if your quad is hard to start, one reason is that it is lean on the pilot circut, then you need to change the pilot jet. I say dont waist $100 on a rev box, have you ever hit your stock rev limiter? I have, but a total of about 4 times, and that was really running through the gears (love the sound of that bike wound up!). I say go with a yoshi, sounds like it is a much higher quality pipe than the white bros. A lot of guys talk about having leaks and poor packing on the white bros. pipe. Get the jets from the dealer (it really is the same thing, you just dont pay for what you dont need) and a uni filter. K&N is nice, but they dont filter the fine stuff as well as a Uni. Keep it oiled and it will be fine (same with K&N, just depends on where you ride: dust=Uni, not so much=K&N) Use the extra money you saved to get a pair of AC standard nerfs. I got mine from http://race.atvaddiction.com/home.php for about $130 to my door. You should be sitting really good after that. Another thing, if you want more speed, spend the $15 to get a 16 tooth countershaft sprocket. It will hurt your bottom end a bit, but it will give you that extra on top. Good luck!

[Dave400ex]

RideRed04, Not to change the Subject, but how do you like the Razrs?

[Deathbringer]

Ridered... no the dealer jets are not the same as the Dyno jets that come with the K&N kit.. and the needle taper is very different which in turn affects your throttle responce.. I ride in the dunes so yes I hit the rev limiter all the time.

"Pilot jet a bandaid fix? No, if your quad is hard to start, one reason is that it is lean on the pilot circut, then you need to change the pilot jet." Wrong... you need to move your clip and that will fix it.. a stock 400ex does NOT need a new pilot jet, even one with a pipe and box mods doesn't.. You go with a bigger bore..YES..then you need to think about stuff like that..


"K&N is nice, but they dont filter the fine stuff as well as a Uni." Well I don't want to say it again..but Wrong..the K&N comes with a pre filter in the kit and if you can get anything through that thing sideways I will replace it free... the pre filter is so fine water almost stands on it.
I am not trying to bash you in anyway but I don't want him to be mislead, what I tell is the truth.. I don't recommend anything unless I have had first hand experience with it.

Williams trust me..if you want a big bang for your buck go with what I said.

[Dave400ex]

If you want a lot more Power then go with the Marcum`s 416 Kit. That has got to be the Best Bang for the Buck. A Pipe and Air Filter will never Add Horsepower like the 416. Just another Idea.

[RideRed04]

I wasnt offended at all deathbringer, I have alot of respect for your opinion, you always tell it like it is. I am still going to stand by what I said before. I still stand behind the fact that a uni will filter better then a K&N. A K&N is a great filter for dunes, mx, etc. Where I ride, we have fine coal dust everywhere, I am not kidding when I say it is dusty 30 min. after it rains. I didnt look before, but I now see he is from So. Cal, so a K&N might be better. Like I said, dust=uni; not so dusty=K&N. Heck, we have a K&N on one of our sportsman 500's, it isnt that I dont like them. If you are letting it rev out, you arent getting the most out of the engine, it starts loosing power at about 7000rpm. If you went up on the countershaft sprocket, then you could go the same speed and be in the meat of the powerband. The needle jet controls about 1/4 to 3/4 throttle. The pilot jet controls idle to about 1/4, and they all overlap. For just starting and idling, if it is lean that is the pilot jet. Honda sent the 400ex out from the factory lean so that it could pass Cali's emission standards. I am not alone when I say that the pilot is lean. You are right in that the needle could stand to be richer too, but same for the main jet. You can buy different taper needles, I dont see what makes the dyno jet kit so special. I am not trying to cut on you, we just ride in different areas, so we need different bike set-ups. Maybe if Bwilliams told us how and where he uses his bike, these details would be easier to sort out.

Originally posted by RideRed04
Maybe if Bwilliams told us how and where he uses his bike, these details would be easier to sort out.


RideRed04,

1st I would like to say Thank You for all opinions mentioned here :)

I live in the High Desert, for those of you that are familiar with southern california. I mainly ride on trails or dirt roads. I don't plan to ride the dunes at this time, but who knows about the future. I have a canyon by my house that I go to and do some SMALL jumping and hill climbing also. The more I get acquanted with my 400ex, the higher the jumps get, but weighing in at close to 230#'s the jumps won't get to high ;)

I mainly want to keep up with the OTHER guys when we ride the trails. I ordered the K&N Power Kit so far and am still researching the exhaust. I think I will end up going with the WB E-Series, but am still open to suggestions.


Thanks Again,

[RideRed04]

Get a yoshi from marcum's atv. He has a few for VERY cheap. They seem to be a better overall pipe then the white bros. but it is up to you.

[Pepto_Bismol]

Hey, I'm a desert rider too, and I live in the phoenix area(very...VERY dusty). I run a K&N power kit with a Yoshimura slip on, and I have AWESOME torque bottom to top. Being an engineer, I'm VERY anal when it comes to my stuff, so I "require" everything to be perfect. It took me about two weeks playing with my jetting before I found the sweet spot. The only reason I suggest a Dyno kit that comes in the K&N power kit is that if you need to play around with the jetting, you have everything right there. Plus, the Dyno needle is tapered to run specifically with their main jet. That's their business, that's all they do. So I trust that they have some precision in their product. Example: I had ok performance with the Dyno jet set-up with 170 main as they suggested, Then, not liking the "2 piece configuration" of the main jet, I decided to go with aftermarket stock jets from the dealer with stock needle. After I installed a 170, 165, then a 160, I didn't like the performence of any of those. I attribute most of that due to the fact that standard aftermarket jets don't have the same tolerence specifications and quality that Dyno-jet produces. So I went back to the Dyno jet setup with a 165 main, needle at 3rd, and my own screw settings, and now I'm flying with NO performance issues of any kind, just great performance. The Yoshi pipe is so crisp too, I can only say great things about it. Thumbs up to Yoshi! Good luck Dude!!!!
Pepto :cool:

BTW, just a point, I hit it hard and fast, but even with my set-up, I have no need for the WB REV box, and my quad fires on the first shot every time, with stock pilot jet and I only paid a total of $340.00 for my deal from Marcums ATV! Fine tuning is an art, we should all be artists!

[Deathbringer]

RideRed04....thank you very much for the compliments, that means a ton to me.. I understand now why you said the dust thing, coal dust sucks!!! I had my quad stored this winter in an aluminum shop and oh my god did it get fine dust everywhere in it, and the K&N filter even though it was covered in the air box it still had a ton of crap on it. I agree with different riding areas you need different setups.... I don't have a clue why the dyno kit makes such a huge difference but it does... I have experienced straight rejetting and I have experienced Dyno rejetting and the Dyno is very very different.. The pull I feel in the midrange is awesome, the lack of "lag" in the throttle responce is hard to describe....

I spend my life at the dunes pretty much anymore and so I come from that angle on bikes. RideRed04, you are tops in my book also and many more happy posts...and I hope you continue to see quality in what I post...

[RED121572]

First of all, would like to say howdy to all the fourwheeler junkies out there, this is my first post.

$500 isnt a whole lot to play with if you want more ponies from your quad. You could do right much if you have about a grand lying around though.

Here is my two cts on what "I" think would work for 500 bucks;
K&N air filter, a good quality slip on silencer and then go rejet it. I wouldnt modify your airbox. (drill holes in it) That will expose your airfilter to the elements that much more. Good luck bud!

[RideRed04]

Nice looking bike! Sorry warrior man for not answering before, I forgot...lol. I havent had a chance to get the razrs on yet (rims should be here in the next couple of days!) but I have ridden a 400ex and a ds650 with them, and was very impressed. They seem to float over sand instead of digging in, and wear decent. The hook up is great, but the way they slide is what sold me on them. I highly suggest them. My buddy that has them popped one the day he got them, and rode almost a the whole ride with about 0 pressure. You couldnt tell, the sidewall is that stiff. The ride wasnt comprimised that much in my opinion. Any other questions, dont be afraid to ask!