[Honda400xRider]

So I’m wanting to do some engine mods to my quad. I’m not too sure what to do to it. I want to squeeze a little power out if it. I don’t want to bore it or do anything like that just yet. I just want to do some cheapER stuff to it. Not trying to get crazy power out of it. Just enough to be a little more than stock. So just give me some suggestions I guess.

 

[retro]

I don't know anything about the 400x, but I doubt that you can put together a symbiotic package on a small budget. There are some things you can do for any motor though, to optimize and improve what the factory gave ya. But those generally take a lot of time and study, a lot of math and testing and a lot of work. In the old days they called that blueprinting a motor... but its much more involved than that. Sooner or later you are going to have to form a plan, stick to it... and buy some parts.

Question: How do you make more power?

Answer: You make more measurable torque. The more torque (force) you can make the more power (HP) you'll make.

So pay no attention to horsepower figures, ever. Leave that nonsense out of all of your plans. Don't even think about power... think torque and make torque. Power is a calculated figure (cannot be measured because it does not ever exist at the crankshaft) while torque is the only measurable figure.

Wanna see a great torque package? Check out SlammedRanger's 400EX vids! He's still making gobs of torque with his motor at his redline shift points! Its a torque monster! But that torque (its power) did not come cheaply... and it did not happen overnight... and it did not happen by buying a random bunch of popular parts neither. It was designed, planned and executed to outperform and overachieve.

You can beat him if you can out think him though!

Have fun!

 

[SlammedRanger]

Full pipe, uni filter and remove the airbox lid. Jet it accordingly and you will have a noticable seat of the pants gain in everything. This is the starting point to all good builds. More air in and more air out add in fuel and bigger bang. But retro is exactly right. To do a full race build you have to have a well thought out plan. All internal mods compliment each other. They all work togeather to make one cohesive power and torque curve. But until you want to go internal start with the basics. What we call the ricer tune up kit where im from. (Named after all the honda civics out there with a fart can and a cold air intake haha). But most of all enjoy the hours you spend putting into it. Its a labor of love. You will never get the money back out of it.

 

[Honda400xRider]

Is there really that much of a difference in removing the air box lid?

 

[SlammedRanger]

Is there really that much of a difference in removing the air box lid?

Yes. Huge difference. The stock snorkle is a straw. Take the lid off and infinate amount of air can be pulled in. As much as the engine wants and intake can provide.

 

[Honda400xRider]

So if I did that would I need to re jet for that?

 

[SlammedRanger]

Yesir you would

 

[Honda400xRider]

So earlier you told me a 155-160-165 jet for right now. If I were to take it off what ballpark would I be looking at?

 

[SlammedRanger]

170-175. Mixture 2 1/2 for sure.

 

[Honda400xRider]

Alright then. I might do that later. It doesn’t have to be done now. With my ridin conditions it might be best to leave it on anyway.

 

[SlammedRanger]

Get an ehs powerlid. Its a outerwares cover over the airbox lid. I ride in alot of mud also just not deep water. Which you shouldnt be in anyway.

 

[Honda400xRider]

If I got the power lid would the jetting still be about 170-175?

 

[RemMax]

Get an ehs powerlid. Its a outerwares cover over the airbox lid. I ride in alot of mud also just not deep water. Which you shouldnt be in anyway.

While I'm riding my blue 300fwd my riding buddy is on a 400ex that he bought recently
His lid was missing when he got it so got another one for him

BUT..... Watcha mean shouldn't be in deep water.
That idiot frequently Parks in deep water, not to mention plowing through or across every mud hole he sees!!

Seems if ya get enough speed momentum will either carry ya across or plant ya in a rut wondering how you landed so far from the bike. ?
Did I mention he's a Idiot. ?

Just removing the air box lid alone won't really add much to your noticeable power but it will make it a Lot easier to flood out
Adding a HP exhaust system and then more air is the quickest and easiest way to create more noticeable"power" in pretty much anythingg
RemMax

 

[SlammedRanger]

Get an ehs powerlid. Its a outerwares cover over the airbox lid. I ride in alot of mud also just not deep water. Which you shouldnt be in anyway.

While I'm riding my blue 300fwd my riding buddy is on a 400ex that he bought recently
His lid was missing when he got it so got another one for him

BUT..... Watcha mean shouldn't be in deep water.
That idiot frequently Parks in deep water, not to mention plowing through or across every mud hole he sees!!

Seems if ya get enough speed momentum will either carry ya across or plant ya in a rut wondering how you landed so far from the bike. ?
Did I mention he's a Idiot. ?

Just removing the air box lid alone won't really add much to your noticeable power but it will make it a Lot easier to flood out
Adding a HP exhaust system and then more air is the quickest and easiest way to create more noticeable"power" in pretty much anythingg
RemMax

Your buddy better buy stock in rear carrier bearings. He will need them alot. And i never said just removing the airbox lid was gunna make it any faster. But with a full pipe it makes a noticable difference in not only power but jetting.