[400EX quick and easy mods] - ATV Riders Forums - Honda, Yamaha, Suzuki, Kawasaki, Polaris, CanAm, Arctic Cat, Kymco ATVs

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400EX quick and easy mods
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Posted by: Badaxe

I just picked up a 05 400ex. It's totally stock and I'm looking for the simple cheap mods to get a bit more power.

I just ordered a HMF slip on muffler and will open up the air box. What's the best way to get more air? Vent holes in the lid? Get rid of the lid? Any tips on jetting?

Anything thing else I can do besides the above?

Posted by: cmaxx

get it ported. remove the air box completly. bigger jets. better filter.

Posted by: tanner 222

ya i agree with cmaxx. but if your gonna remove the air box make sure you get an outerwear

Posted by: REDRIDDER

best $20 i ever spent $ for $...http://www.atvriders.com/articles/timingkey400ex.html

Posted by: oleboy87

depending on what kind of riding you are going to be doing i wouldnt remove the airbox... i have an hmf slip on and im at sea level running open airbox and k&n filter stock motor othan than that... im running a 170 main jet....

Posted by: flauge

Get you an ehs raicng lid, its like an outerwear but its held in place by a bolted down bracket instead of velcro like on the regular outerwears. You could take the choke out too, it makes a difference on throttle response.

Posted by: XXXRACER165

Get a cam HCS1, Wiseco 11:1 piston, port it + a pipe & power kit. With that you'll probably get a good 35 hp.

Posted by: dariusld

quote:
Originally posted by Badaxe
I'm looking for the simple cheap mods to get a bit more power.

What part of this didn't you guys get? I don't think a port, or many of the others listed, falls into this catergory.

Posted by: XXXRACER165

Well then a Pipe & power kit is about it. And you wont notice much of a power difference.

Posted by: oleboy87

well if he is riding a stock machine then he will notice a difference! and i hear that the timing key makes a big difference!

Posted by: Badaxe

Thanks for the help guys. I'm going to start with the slip on and opeing the air box and re-jet then see how it goes.

Posted by: Badaxe

quote:
Originally posted by XXXRACER165
Well then a Pipe & power kit is about it. And you wont notice much of a power difference.

Don't mean to sound stupid but what's this power kit you speak of? Jet Kit maybe?

Posted by: honda8&3

quote:
Originally posted by Badaxe
Don't mean to sound stupid but what's this power kit you speak of? Jet Kit maybe?

I am pretty sure that he is talking about this

http://www.motosport.com/offroad/pr...6263&nav=&sMMY=

Posted by: FoxHondaRider

jet kit and air filter. some power up kits come with a hot cam too. If your all stock now i say get an HMF slip on, jet kit, and a k&n airfilter. With that you will see a huge difference. Way more torque, quite a bit of HP increase, and deffinately more throttle response. HMF gives great gains for little cash. HMF is just below curtis sparks in my book. If you still want more and want a crazy fast quad compared to stock get a cam on top of that. If I ride my brothers with the HMF slip on, dynojet kit, and K&N then get on mine it feels like it doesnt move. With the combo of those no more bogging down. Then before when he had the cam it was amazing

Posted by: honda8&3

quote:
Originally posted by FoxHondaRider
jet kit and air filter. some power up kits come with a hot cam too. If your all stock now i say get an HMF slip on, jet kit, and a k&n airfilter. With that you will see a huge difference. Way more torque, quite a bit of HP increase, and deffinately more throttle response. HMF gives great gains for little cash. HMF is just below curtis sparks in my book. If you still want more and want a crazy fast quad compared to stock get a cam on top of that. If I ride my brothers with the HMF slip on, dynojet kit, and K&N then get on mine it feels like it doesnt move. With the combo of those no more bogging down. Then before when he had the cam it was amazing

HMF slip on with an FMF powerbomb header jets and filter. Also a cam is great but for simple mods like foxhondarider and I said. Set you back about 650 dollars with a huge increase for what I said.

Posted by: FoxHondaRider

You could do without the powerbomb header for now though. I'm still debating whether there is a noticeable or good increase in power with the powerbomb header or not. my brother has the HMF slip on but is looking for a little more without doing engine work because last time the timing chain snapped after the cam was in for a few months and that shreded he inside of the motor so he got that replaced, then his valve broke off and went through his piston lol. but i think thats because the high compression piston had a little too much compression.

Posted by: Badaxe

quote:
Originally posted by honda8&3
I am pretty sure that he is talking about this

http://www.motosport.com/offroad/pr...6263&nav=&sMMY=

Thanks for the link.

Posted by: FoxHondaRider

its cheaper to actually buy them separate if you didnt know. You can save a bit ordering the parts that are in the kit separately. They kit just has it all packaged in 1 thing but ordering the jets and airfilter separately will do the same thing but leave more money in your wallet

Posted by: FoxHondaRider

For the same things separate it cost $126.97 vs. $134.99. But thats motosport, the K&N and outerwears are much cheaper on rockymountain. You will save another $10 or so. So around $115 for it all on rockymountain ordering them separate.