Hello all. I ride a '02 Raptor. My friend just got an '00 400ex. While it is a nice quad, it just doesn't go like my raptor does. We want to give it a noticible improvement in power without going into the motor at all if possible. Will a full exhaust and dynojet kit with open airbox lid wake this thing up? What mods can we do to this 4wheeler to make it faster without opening the motor up? Is there some kind of rpm limit remover or something that helps ( I think I read this somewhere) What about better intake boots or something, as the stock rubber ones look like they could use some improvement? Any and all mods would be greatly appreciated. This bike is on a budget. thanks and get back asap.

Mike
Houston, TX

 

When I had my 400EX. it was stock dynod at around 23-24HP. With a white Bros slip on a jet kit and big holes in the lid, Trinity dyno tuned it and got 28.4HP.

Total cost $220 pipe, $50 Jet kit, $0 Holes, $100 dyno tune.

Smitty

 

Sounds good, thanks for your mods. The $50 jet kit, was that a "Dyno Jet Kit" or another jet kit. My jet kit for the raptor was like $85 ouch. Any reason that you didn't do the full exhaust? Is it not necessary or did you just not have the cash? I know there has to be more tricks for this quad. It has been around long enough to have them I would think. Something more than exhaust, k&n and jet kit...

Thanks.

 

instead of buying the jet kit i would just buy the individual jet that you need. the jet kit comes with many jets that you will never use. jetting is trial and error. what i do is go buy the jet that i think i need from my honda dealer and start there. the jet is like $3.00. if it is the wrong size i take it back and exchange it with another. this will just save you $45 or so. just a thought

 

Yah, sounds alot cheaper, which my friend will like. But I still need to get this thing moving. Its top speed wasn't bad, but it was the lack of acceleration that bothers us. Don't get me wrong, it goes alot better than his timberwolf [img]i/expressions/face-icon-small-smile.gif[/img] but it needs some more umph. We are definitely doing the full exhaust, jetting, and airbox mods, but comeon, there has to be more without opening the motor.

 

The Dyno-jet kits come with a arrangment of main jets to create the stage 1,2 or 3 for which ever mods you are running and the adapter to run the standard main jets, and a new needle with a different taper for your mid-range.

The mods that we are running on my wifes 400ex are as follows: Supertrapp IDS-2 slip-on, K&N filter and outerwear, no air box lid, 170 main jet, the new needle on the center position and the air mixture screw 3.5 turns out.

For a stock motor, they (www.powroll.com) say the stock head pipe flows plenty, until you start getting into cams, high comp piston or big headwork.

Now my application is good from sea level to approx 4000ft, then for above there they say to goto the 165 main and 3 turns out on the mixture screw to lean it out .

 

Well then, a slip on it is. Chicneater, how much of an increase did your wife's mods provide. I don't care about HP, i'm talking feeling. Was there a marked noticable difference? When you hit the throttle were you like this is more like it or were you like I think I can feel a little more power? Have any of you used the rev box?

 

Yeah, we could feel a difference, especially when were out in the dunes riding, it seemed to give it that little extra. After we did that stuff, we also dropped a tooth on the front sprocket. You can get a front sprocket from your local dealer or thru www.rockymountainatv.com , they are the ones we order the most from.

 

Well I don't care what "they (www.powroll.com)" say. I have a full WB ProMeg system on my 400ex and I could feel an incredible difference between it and my friends 400ex that has a WB e-series slip on.

 

Yeah, that half a horsepower from the Pro Meg is WELL WORTH THE EXTRA $200! Don't you know that each engine responds to pipes differently??? Yeah, your ProMeg might work better on your engine, but then it might suck on his engine. A good quality slip-on like the E-Series is the way to go. Also, get the extra 6 disks and the longer screws. You'll wanna play around with different configs to get the bike running to your preference. I ran mine with all 18 disks in.

And STAY AWAY FROM 2 THINGS!
1: K&N Air filter. Go with a UNI or Mooose or any dual stage foam filter
2: Dyno Jet kits. They are not worth the money. Just buy new main jets

Then drill a 3" hole in the airbox lid, insert a sub box port tube, cut some foam out of mom's new couch(joking!) spray it with filter treatment, and put the foam into the port hole. This will give you more airflow. I wouldn't run a quad in Texas without an airbox lid....too dusty.


And the number One best bang for the buck horsepower gain....The infamous "FOX HEAD" sticker below the headlights on the front plastic.....adds 2.2048hp in most 400ex's....