Best 400ex power upgrade(s) for $500

[McGivern]

Hello Everyone,
I just joined the forum, and I just bought a 2001 400ex. I also ride a modifed XR600R.

In order to make sure I can smoke by buddies with 400ex's, what should I do in the first $500 or so in upgrades? I do trail riding in the Arizona mountains and desert. The main thing is I want the quad to be relable.

Here are the items I'm considering:

1. exhaust - only thing here is I don't want it real loud
2. WB rev kit
3. air filter
4. re-jet or new carb?
5. cam - XR cam or after-market? I don't want to change springs/etc.
6. piston- I'd like to stay around 10.5:1

I can't do all this at once, so where should I start?

Your input is greatly appreciated.
Mark

[GNCC#829]

I would do #'s 1 and 3 and definately remove the airbox lid.

[Justin330ex]

Go with a pipe , slip on , air filter , rejet and if you got enough money get a performance cam , next step is rev kit after that get a high comp piston
Youll have a sweet bike with tons of bottom and , mid range , more top also

[yellow400rider]

i'd go w/ a full exhaust, re-jet the carb, and mod the airbox lid. (either run w/ no lid or do one of the many alternatives...such as holes, outerwears, etc) this is the plan that i am going to take first. this will b right around your budget of $500. then get the FCR 39mm carb :D if u ride trails a lot which i do as well i dont think the stock tires are all that great. im going to invest in some razrs real soon. also my ac pro peg nerfs are on order and ill feel a lot safer riding around with em. happy modding
joe

[McGivern]

Thanks for the input so far...

As for the exhaust, I have an XRsOnly full system on my XR600 and they make one for the 400ex.

Anybody running the XRsOnly pipe?

Mark

[yellow400rider]

hope i dont sound dumb but i have never heard of the pipe that u r talking about :confused:

[BadA$$440]

Get yourself a nice exhaust or slip on even. Then a airfiler so it can breathe.

Then get a 416 kit ($165, includes boring the cylinder) Hotcams Stage 1 or 2.

Some good tires.

Maybe a 36T rear sprocket to get a lil top end.

[MX26]

Since the pipe adds the least power, I'd go ahead and get an air filter(K&N or UNI, TwinAir makes a good one too), Rejet it, take that airbox lid off, and maybe change your gearing.

Slipons are great, but on a dyno they alone provide the least power gain.

[wilkin250r]

You could add a nitrous kit for $500.:D

Oh, that's right, you said reliable...

[TrX465]

buy the W/B 440kit 250$
install sleve & bore 100$ to 200$
you tear down and ***. 0$
take off air lid and rejet under 50$
keep it stock looking now you have a real sleeper:)
can you imagin the look on the face of that guy riding a stock rapter or banshee? thats what i love

[RAPTORAZ]

Where abouts do you live in Arizona? I've only have about $500.00 (mod list in signature) in engine mods, including the slip-on, on my EX. We could probably hook up and go riding sometime if you'd like a demo.

[13RAZOR13]

RAPTORAZ me and TrX465 ride at 107 & Jomax Im there allmost every sunday eve. around 4:00 to 5:00 after Im done with all of my honey due list..... I have a red and blue drag Banshee With no back fenders. TrX465 most of the time lately has had to workon the weekened, hope to see you one off these days. Where do you ride?

[RAPTORAZ]

Most of the riding I do is at Glamis. I haven't done much desert riding since the closure of the river bottom (107th and Camelback). The closest place I knew of on this side of town was 339th and I-10. I didn't know there was any riding at 107th and Jomax. What's the area like? Size wise and terrain?

[13RAZOR13]

I live down the street from here and Its the last spot I know of thats still open & close to town. Some times their are alot of people out here on the weeknds sence everthing else has been closed down.There are some inclines,some trails,some small jumps,a river bottom thats too rocky for me in some spot(small bowlls),and a nice dirt road wear every body drags. The cops will give you a ticket if they catch us on the road sometimes but most of the time they are kool and just tell you to stay off of the road. We go to glamis and the cynders but we hate to go to the haseampa rive(339 & I-10) we allways feel like gust keep on going toGLAMISSSSSSSSSSS:)

[jb400exxx]

get a slip-on, and K&N power kit, that will be about $300. i got my pipe and K&N kit from moto-man.com for $295 w/shipping. then spend another $300 and get a JE 11:1 or 10.8:1 piston with a hot cams stage 1 or 2. it will be a little over $500 but it will deffinetly be a really fast quad. total it will probably cost about $550 - $600.

[Dave400ex]

Get a Slip-On, good Foam Filter, some Jets, then a JE 416 Piston and the Cam you want. Go with a Drop-In Cam.

[jb400exxx]

me and warriorman got the idea. i can't wait to do my 416. i think i should be in the 35-38HP range after that, i hope. then probly in the 38-42HP range when i get the 39 fcr carb w/some porting.

[Dave400ex]

Yep. After you get the other stuff, then you could get your Head Ported and the FCR Carb like jb400exxx said.

[jb400exxx]

then get long travel +2 Arens A-Arms, and elka quadrate suspension, and get your rear shock modified, and maybe an rpm adjustable axle, and +1.25inch extended swingarm, race rims. and on and on. lol

[2 QuicK]

Then get a 18 pound Lonestar Titanium Frame. ;)

[jb400exxx]

yea, right. lol for what, 10 grand?

[racin 400]

well put that xr600 motor in ur 400 frame that would show em up.

[McGivern]

For now I think I'll do the slip on pipe, filter, jets, cam and piston. But the 400ex is definitely getting my modified xr600 engine in good time. 55HP sounds like it would be fun in the quad.

[13RAZOR13]

Dont forget about lighten your fly wheel, its a real good cheap hp maker
good bang for the buck:)