Squeezing more power from XT400

[worzal07]

Just bought XT400 & was wondering if replacing exhaust system & air cleaner system with aftermarket type would increase both the power & torque output & would i need to re-jet carby ?

[James Deuce]

The cheapest, easiest, and least trouble power upgrade would be an XT600 engine.

[Motu]

I've got a couple of threads out there about my XT400E.....and now it's an XT600K.I'm suprised that it's not that much more powerfull than the 400....you need less throttle to go just as fast.Much rougher and noisier.As I ride a lot of gravel the thing I liked about the XT400 is that I could ride it as hard as I could push it....I really like a bike like that.The 600 just needs less work to go the same speed....and less fun.But much better on hills and wind - and there was sure a lot of wind today,the 400 would of really struggled.

As a 400 I ran a Supertrapp and lifted the needles a notch.You can't improve the air flow I found out - they run the same size carbs as the 600 and restrict the intake,any improvment in air flow kills them....it'd need a major rejet.

[Crisis management]

I don't know what your intending to use the bike for, but if it's general gravel roads and the odd farm track (like most of us) is it really important to get more power out of it? The rides I've done are usually at 40 to 100 km/hr and the DR very rarely gets wrung out, I would have thought an XT400 could easily have kept pace.
The reason I raise this point is that when I first got the DR, I was making lists of things to do to extract more power, but having now used it for a while I question whether I need that. Ultimately I will improve it's performance but I am no longer in any rush to do that. My advice would be not to rush into extracting more power unless you have a specific need.

[worzal07]

Thanx guys for your advise,i agree that i haven't had bike for very long & should hold off thinking about changing exhaust.Being only 5'4 I definately prefer the seat height & weight of XT400 compared to XT600 & it handles real sweet going along scenic drive in Waitakere.I think the bike is running too rich as plug quite black & sooty,how difficult is it to adjust air/fuel mixture,can any DIY do it ?

[Crisis management]

Give the bike a complete tune rather than just adjusting the idle mixture. New plug (correct type?) clean air filter, change oil, check timing (is it adjustable?) check the choke is closing off completely and lastly adjust the idle mixture screw to give it a smooth idle.
If you haven't done these types of things before, get a manual from tech books or possibly the library, have a read and see how capable you feel.
If you want a hand send me a PM and I will see what I can do.......





You thought it was going to be easy, didn't you!

[worzal07]

Thanx dude- I should have checked air filter sooner.It was a real shocker!! I'm sure that was the reason it was running rich - Got new filter coming tomorrow.

[Crisis management]

Thats good news, nothing like an easy fix eh!
Take the condition of the filter as an indication of the level of maintenance carried out tho.......do an oil change & tune asap, and get the maintenance up to scratch!

Enjoy!