more power

[99exrider94]

:confused: Ok so i was wondering how to grinnd the head pipes down (the part thats goes into the engine) i am not sure exactly what to do and how? im just trying to get the most out of my 400 at low cost!!!!



also how would i jet with this mod plus ehs airbox lid and my performance exhaust insert?

<br>
thanks in advance:confused:

[JOHNDOE83]

the cheapest ways to get more power are ditching the airbox, choke removal, get rid of the oil catch on the intake tube and plugging the hole on the intake boot, then putting a small filter on the crank case breather tube, header welds and proper jetting.

if you do all these at once, youll notice a good lil gain in power.

if you do a search there are threads on removing the header welds with pictures.

[99exrider94]

cool thanks about the choke removal how would that do with cold starts.


im new at this i just ride and do the normal chain and sprocket and oil change stuff lol but now i wanna go deeper into it lol just need a lil help

[JOHNDOE83]

for the choke removal you get a bigger pilot jet.

try a 42 pilot jet, no choke is needed, you just pump the throttle a few times and hit the start button....if it doesnt do it so easy try a slightly bigger pilot jet.

42 was fine for me at sea level with a 440 kit so you should be fine with the 42 also.

I just unscrewed the choke plate, then popped the black cap off of the carb where the choke lever is and I basically pulled the rest right out. put the cap back on and it was done.

It was several years ago, there may have been a lil more to it, but its self explanatory once you start doing it.

[99exrider94]

thanks man i got my quad all apart in the garage lol i cant wait to do this i also was wondering how to do the header mod i kinda have an idea put i dont wanna screw it up lol no cash to fix it if i do

[Kentang4]

There isn't a lot to screw up on the header but here are a couple of suggestions...Stuff some rags down into the pipe before you starts so you don't end up with metal chips deep inside the pipe. They will stick to the oily inside and most likely end up in your muffler packing, spark arrester screen etc. Worst case some could end up back in the motor. Just shove them far enough down so you don't get them wrapped up in whatever tool you use. I used an air powered rotary file to remove the metal and it made quick work of things but I'm sure it could be done with a dremel tool also. The only other thing to be slightly leary of is removing so much metal that you free the collar from the pipe. I was pretty aggressive and didn't have any trouble, but pay attention to how much weld is still holding things together. You could always have a few tack welds added to the outside if you remove too much material but it shouldn't be a problem. This is a great mod and well worth the time. I'm pretty sure someone has posted pics of this mod on the site so search around a little if you still aren't comfortable. Good luck.

Kent

[TRXRacer1]

Ditching the air box gains you nothing. You can leave it in place and just remove the lid and get identical results with far better protection.

[tri5ron]

Originally posted by TRXRacer1
Ditching the air box gains you nothing. You can leave it in place and just remove the lid and get identical results with far better protection. ditto

[JOHNDOE83]

It does do more then just taking the lid off, whether or not its worth it is up to the person doing it.

If your trying to get every last bit of power, it will take away weight, and flow better, resulting in more power.

In my case, it was worth doing, If you want the "protection" of the airbox, then leave it.

Thers no reason to say it does nothing, because it does add power.

[99exrider94]

yea i was gonna do the lid mod.. outerwwears thing

[bkelley]

After running no airbox for a bit I've decided that I am going to build a custom aluminum box. The realization came when I was flying around a corner and found myself hitting some water in 4th gear. Not only did I suck in some water and stall the bike, but I also burnt the crap out of my exposed legs from the water instantly vaporizing after hitting my hot engine. Sure, no airbox is good in theory and in ideal conditions (dunes, drags, etc) but on the trails it's a different story. It's not worth the extra flow to have your filter covered in dirt and exposed to water and mud. I've even heard that having a little restriction is better than a completely open system.

[TRXRacer1]

Originally posted by JOHNDOE83

Thers no reason to say it does nothing, because it does add power. No it really does do nothing for power. The filter setup for the 400ex is outstanding and even if you did a 500 build you still wouldn't gain anything totally removing the box.

[JOHNDOE83]

Well i guess theres thousands of drag racers and duners that are wrong?

I guess they have no clue what they are doing?

I wonder why there quads and bikes are so fast then?

Im not trying to argue with you, but theres enough evidence to back up what im saying.

[TRXRacer1]

Originally posted by JOHNDOE83


Im not trying to argue with you, but theres enough evidence to back up what im saying. Nope, no evidence. Just because people are misguided or think it's cool don't make it so. The era that this concept is inspired from had no choice but to do clamp ons for max flow. Things have changed, filter setups are light years ahead from where they were and you'd have to build a 400ex beyond what anyone has ever done here at atvriders to even get close to having completely remove an air box to begin to make sense.

[JOHNDOE83]

LOL....ok man, like I said Im not gonna argue.

I never knew airboxs were so "advanced".

[honda400ex2003]

Originally posted by TRXRacer1
Nope, no evidence. Just because people are misguided or think it's cool don't make it so. The era that this concept is inspired from had no choice but to do clamp ons for max flow. Things have changed, filter setups are light years ahead from where they were and you'd have to build a 400ex beyond what anyone has ever done here at atvriders to even get close to having completely remove an air box to begin to make sense.

thanks trx! i was hoping you would chime back in. lol it really is great to have you back! I am tired of saying it how it is to get shot down lol as you notice i have drastically cut my posts in the past few weeks. I still look for your posts though to read an informed post every now and again. :D Totally removing the airbox is a waste of time! steve

[TRXRacer1]

Originally posted by honda400ex2003
thanks trx! i was hoping you would chime back in. lol it really is great to have you back! I am tired of saying it how it is to get shot down lol as you notice i have drastically cut my posts in the past few weeks. I still look for your posts though to read an informed post every now and again. :D Totally removing the airbox is a waste of time! steve LOL, it's been fun. Sometimes I'm just a stubborn ***** but things like this are like... really people?? I've got nothing against John either, most of the time I very interested in what he's posting but this one is just a new chapter in internet misinformation.

[honda400ex2003]

I too have nothing against John and that is true some things are just believed. no offense to anyone with any of my posts. I also like to stir the pot every now and again. lol. steve

[beags86]

Originally posted by TRXRacer1
LOL, it's been fun. Sometimes I'm just a stubborn ***** but things like this are like... really people?? I've got nothing against John either, most of the time I very interested in what he's posting but this one is just a new chapter in internet misinformation.

sometimes i feel like trx is the only person on here that agrees with me. thank god i have one friend instead of foe....

[beags86]

Originally posted by honda400ex2003
I also like to stir the pot every now and again. lol. steve

i know where your coming from, i like to do the same...

[honda400ex2003]

it keeps the site live enough for me to stay coming. lol steve

[99exrider94]

well thanks for the info.. im just gonna do the outerweears lid(make my own) but what jetting should i use ... thats were im stuck i was guessing around 152 mian and 42 pilot with the lid mod and grinded down headers.. plus a choke removal

so does that jetting sound right or close