Looking to gain power ltz400

[1capper]

Im looking for some ideas on how to gain some power from a stock ltz 400. I say stock because i dont want to put a big bore on it its the kids bike. I have a full yoshimira exhaust,k&n air filter,fresh valve job and a pro com rev box. I have not put the head to gether im wondering from here what else i can do to get more power. maybe a hot cam or different intake etc.........

[vicsdvx400]

get the honda 400ex intake boot and the air filter. that's supposed to give you 2-3 hp gain. I got it done on mine about 2 weeks ago and will be rejetting my carb this weekend and then taking it out to the pismo dunes to see if i can notice a hp gain.

[twincat800]

Yeah i think what he says about the boot will help out and the cam as well, if you want to go a little cheaper route i know that some people leave one of the cams stock an upgrade the other because it doesnt help out as much as the other one does, not sure which one that would be though.

[locutus]

What about the 3x3 mod that the DRZ riders do. I did it to my DRZ and there is a big difference in power.

[1capper]

What is the 3x3 mod?

[cjmadison9]

people usually replace the exhuast cam and leave the intake stock, it works but if ur in thier you should upgrade both lol, i put a aftermarket rev box on mine for the track and it helps, ups ur rpm range...exhaust pipe will make a noticiple difference and im not sure about the 400ex air boot, i here lots of people talk about that but i never done it, might have to look into it!

[verno769]

the 3x3 mod is cutting a 3x3 hole in the top of your airbox. ive done that on my drz. but on a quad just take the air box lid rite off.

[locutus]

I assume you need to re jet to whatever the DRZ uses for jets as well?

[twincat800]

They DRZ is the same carb they wouldnt have different kinds of jets, different sizes, yes and the DRZ I would think already has a bigger jet than any of the 400 quads. Not sure on that though.

[350ex]

If you are running a rev box you should use the drz dual valve springs. Not too safe to raise the rev limit much on the stock springs.

[vicsdvx400]

the 400ex intake boot does really make a difference! I installed it a few weeks ago and just got my carb rejetted today and took my dvx down the street and I definately feel the difference... It was a little hard to keep the wheels on the ground in 1st and 2nd gear at wide open throttle. Will be taking it out to the dunes tomorrow since there are so many people racing at pismo dunes. Hopefully the 450's don't beat me by as much now... haha.. they probably will!

[cjmadison9]

does a 400ex intake boot fit right on a z or kfx? do you need to change the jettin on it if you do?

[vicsdvx400]

yes it does fit right on... only thing you need to do is modify your airbox so the wider intake boot fits and that's it... then you will be able to run a bigger air filter as well as the wider boot. You will definately need to rejet other wise you will be running lean. I went with the stock pilot, 150 main, dj needle third clip from top and pilot screw 3.5 turns out and it runs great. I'm running a full exhaust though too and no lid on airbox.

[Limited Z_400]

Iam not convinced that a 400ex intake will get you 2-3hp.The fit is not that great. I replace mine with stock tube because the pervious owner did not fit it properly so it dusted the engine.If you go with the ex tube do your homework and fit it properly.

[vicsdvx400]

have you seen the difference between the size of the stock intake boot vs 400ex boot... it's a big difference!

[350ex]

You dont need to modify the airbox because the ex boot is larger. You need to modify it because the ex boot gets smashed by the shock mount. The air box inlet needs moved up. I just got done modifying my airbox for better fitment. I had the ex boot on before that with the stock airbox with no issues other than the boot being squished. I believe the big difference with the different boot is that it is a straighter shot between the carb and the airbox. The stock boot curves around too much and disrupts the airflow.

[vicsdvx400]

well that is the reason why you modify the airbox... so the boot fits properly and you don't have any issues like you said you did....a smashed boot is definately an issue!! What's the purpose of having it if it's gonna be smashed it's just gonna restrict airflow and you will get no additional power whatsoever.