Need Help on Making the Fastest/Stock Looking 400ex!

[cheater13]

Well, this Winter i want to get my 400ex worked on again. I drag race it and field ride it with little trails, but that's about it.

I want to get everything i can do to it done to make it the fastest it can be. All inside-the-engine work. I need to keep it stock looking so i can enter in the stock and beginner class in my drag races. ;)

But remember, it needs to still be field-riding worthy and reliable.

Everyone at the recent drags though it was a 450 since i was making a killing on the drags. My best was a 4.9 this year compared to my 5.1 last year, beating alot of 450rs, yfz450s, and some Raptor 660s.

There was a monster 2 stroke bike killing everything holding a wheelie down the track. Along with a Can Am Renegade and Artic Cat 1000, but they were in other classes thank god.

So any suggestions on some good builders i could ship my cylinder to? I need to ship my head to gtthunder still because i snapped my stock head studs again. :p

I heard fourstrocktech is pretty good? I just dont want to spend a grand or so on this and it breaking all the time and not being reliable for my daily field ripper.

Here's some pictures to keep you all entertained:

http://i396.photobucket.com/albums/pp47/cheater13_photos/null-21.jpg (http://s396.photobucket.com/user/cheater13_photos/media/null-21.jpg.html)

http://i396.photobucket.com/albums/pp47/cheater13_photos/null-20.jpg (http://s396.photobucket.com/user/cheater13_photos/media/null-20.jpg.html)

I just had the underglow on that blue cause it looked cool. It has many colors+strobe effects to choose from. :D
http://i396.photobucket.com/albums/pp47/cheater13_photos/IMG_0671.jpg (http://s396.photobucket.com/user/cheater13_photos/media/IMG_0671.jpg.html)

http://i396.photobucket.com/albums/pp47/cheater13_photos/IMG_0670.jpg (http://s396.photobucket.com/user/cheater13_photos/media/IMG_0670.jpg.html)

http://i396.photobucket.com/albums/pp47/cheater13_photos/IMG_0667.jpg (http://s396.photobucket.com/user/cheater13_photos/media/IMG_0667.jpg.html)

http://i396.photobucket.com/albums/pp47/cheater13_photos/IMG_0638.jpg (http://s396.photobucket.com/user/cheater13_photos/media/IMG_0638.jpg.html)

http://i396.photobucket.com/albums/pp47/cheater13_photos/IMG_0658.jpg (http://s396.photobucket.com/user/cheater13_photos/media/IMG_0658.jpg.html)

[cheater13]

Wow, so much help! Thanks guys!

[400man]

patience young grasshoppa......high compression, like 12:1, bore size doesn't matter too much, aggressive topend cam with hardend rockers and stiffer valve springs, ported head, 450r carb or yfz450 fcr carb,, xr250 dirt bike cdi box (higher rev limit), stroker crank if you want to split the cases, full exhaust with shorty silencer, but don't "hollow" it out.

[DragonGunner]

You have already done most everything....can always experiment with different gearing, a longer swinger could help keep the front down better. Higher compression with race fuel, or bore to a 407 or 416 with higher compression.

[JOHNDOE83]

I never got a trophy :tired:

[JOHNDOE83]

If you wanna take another few tenths off your time, strut the front and back then remove your air shrouds, thats good for about 40lbs off the stock weight of the quad.

[cheater13]

patience young grasshoppa......high compression, like 12:1, bore size doesn't matter too much, aggressive topend cam with hardend rockers and stiffer valve springs, ported head, 450r carb or yfz450 fcr carb,, xr250 dirt bike cdi box (higher rev limit), stroker crank if you want to split the cases, full exhaust with shorty silencer, but don't "hollow" it out.
I have most of that done besides bigger valves, different springs, and I guess I could go to 12:1 later on as long as I can run 93 in it for field riding. I'll get that rev box sometime here because I heard that's similar to white brothers. I just can't find any more white brother ones. Don't really wanna stroker crank yet until something happens to mine though. :p


You have already done most everything....can always experiment with different gearing, a longer swinger could help keep the front down better. Higher compression with race fuel, or bore to a 407 or 416 with higher compression.
I think I got the perfect gearing for 250-275 feet (13 front, 40 rear), but I don't think I wanna worry with a swinger and having to switch it out all the time. The front stays flat on the ground how it is when I take off. I run 112 octane in it for racing only.


I never got a trophy :tired:
Me either! I just happened to get one for the barrel racing because I'm good at that! :D

[Zakradu398]

All you really have left is a more agressive cam (webcam) which requires rockers and springs I believe and bigger valves without tearing into the bottom end. I highly doubt you can run 12:1 on pump (93) but I have seen it done... Best bet is weight reduction.

[cheater13]

How do I know what kind of webcam to order? And what about boring to a 416 or 427?

Would doing the rockers/springs/bigger valves decrease the reliability? Since I don't have a shop nearby, who could I get to do this?

For my next drags, i'm getting them Douglas .125s instead of my regular stock rims. That should help some. Plus, I guess i'm going to get an HMF slip on so I can retire the old FMF Titanium. I'm going to make the FMF into a shorty and see how it does when I get the HMF so I can compare.

[Chukkinsod]

If you are going to drag an ex....light = fast. take off everything. You can leave the plastic but may want to drag cut. If you run struts in the front and back and remove the front brakes...huge weight savings. Also run the 125s like you stated and no front bumper. The front end WILL come up quicker the lighter you make it...so you will have to play with gearing and/or slip the clutch out of the hole or run a wheelie bar. Rev box does not produce additional power but it will allow it to not hit the limiter as quick (shifts). Leave on both bars (Handle and wheelie). Wide open on the limiter out of the hole. Nothing more rewarding than to beat a bigger bike. Setup is everything on these as most are modded and produce similar power.

[cheater13]

If you are going to drag an ex....light = fast. take off everything. You can leave the plastic but may want to drag cut. If you run struts in the front and back and remove the front brakes...huge weight savings. Also run the 125s like you stated and no front bumper. The front end WILL come up quicker the lighter you make it...so you will have to play with gearing and/or slip the clutch out of the hole or run a wheelie bar. Rev box does not produce additional power but it will allow it to not hit the limiter as quick (shifts). Leave on both bars (Handle and wheelie). Wide open on the limiter out of the hole. Nothing more rewarding than to beat a bigger bike. Setup is everything on these as most are modded and produce similar power.
I don't want to run struts due to the condition of the track. It's too risky. But i'll do my wheels and leave the front bumper off. My gearing is already 13/40 so that's perfect for me cause I only go from 2nd to 3rd gear the whole way.

I might get it bored to a 426 and get some more head work done. I already hold the limiter out of the hole. And when I shift.

I got a Big Gun rev box recently but it probably won't do too much.

What about sand tires for the front compared to my asphalt drag tires since they have the "floating" effect?

Remember... I want to keep it stock looking. No wheelie bar, lol. I have a lowering kit on so I should be fine.

[Chukkinsod]

I actually run Skat Trak Mohawaks for my fronts for weight...many run smoothbuffs. They will be considerably lighter than your asphalt tires but are not as durable (Ply). We race on Sand here so dont have to worry much about rough track conditions.

[cheater13]

Well sometimes we go when its alittle muddy so I need some more traction than my asphalt ones.

I didn't know if the cheap sand tires with the line or two of tread down the middle would be better or not.

[RNL]

How much do the stock rims weigh in comparison to the .125's?

[cheater13]

How much do the stock rims weigh in comparison to the .125's?
Not sure. I'll have to do some research on that when I have time.

[cheater13]

Bump.

What do you guys think of sand front tires for drag racing?

[johnbanghart]

love your number plate :)

[cheater13]

love your number plate :)

Haha thanks. :D I have a real one but they require a paper one they give you just to count how many drag racers we have.

[i973eat1]

If I was you, I would strip everything that you do not want/ need on it. Also you could adjust your rear shock to be stiffer. (That could cause the front end to come up more easily, so keep that in mind) Remember what Chukkinsod said, light=fast. The better power/weight ratio you have, the better off you will be. Just a few things to keep in mind...

[cheater13]

If I was you, I would strip everything that you do not want/ need on it. Also you could adjust your rear shock to be stiffer. (That could cause the front end to come up more easily, so keep that in mind) Remember what Chukkinsod said, light=fast. The better power/weight ratio you have, the better off you will be. Just a few things to keep in mind...

Yeah I'll be working on that this year. I need a new rear shock because mine's totally wore out. I'm working on making it light. The .125s for sure will make it better. I'm just wandering if I should switch to sand front tires or keep my drag fronts.

The only bad thing about my drag fronts are that if it's any type of muddy condition, I have zero steering.

[i973eat1]

You could always use a skinnier front tire. The less resistance that there is to rolling on the ground, the faster/ easier it will roll.

[cheater13]

You could always use a skinnier front tire. The less resistance that there is to rolling on the ground, the faster/ easier it will roll.
Yeah, but as you can see on the first page, them asphalt tires are pretty small and narrow. Not sure if the sand tires with a strip of tread down the middle would be any lighter or not though.

Something like these: http://www.rockymountainatvmc.com/p/43/-/165/723/146/24687/Duro-Sand-Master-ATV-Tire

Or I could get these in 19x6: http://www.rockymountainatvmc.com/p/43/-/165/723/146/24121/ITP-Sand-Star-Front-ATV-Tire

[i973eat1]

Well, the million dollar question is what surface are you drag racing on? Plus are you gonna have a separate set of wheels & tires that you are going to run if you are trail riding?

I think that I would go with the second option if you are running in mostly sand, if you are running more in mud, i would go with the first ones.

[cheater13]

It's a hard packed dirt. If it rains it'll be muddy though.

And yep, I have 2 other sets for woods riding so I'm fine with that.

[i973eat1]

Then I would go with thesehttp://www.rockymountainatvmc.com/p/43/-/165/723/146/24687/Duro-Sand-Master-ATV-Tire They would probably be the best ones to have, and have the least rolling resistance on the hard packed dirt, the only problem is I am not sure how they would do when it rains and is muddy.

[cheater13]

Just picked these up today! What about them? They're skinner but alittle taller than my other ones.

http://i39.tinypic.com/2edw4rr.jpg

^If the picture is sideways, blame tinypic.

[i973eat1]

All you can do is try them lol.

[cheater13]

I'm going to see if I can find someone that can switch my smaller tires onto my blue labels. Then ill just keep the stock rims with my new drag tires as a back up.

Right now, how both setups sit, they both weigh a hair under 10lbs per each tire/wheel.

[JOHNDOE83]

I'm going to see if I can find someone that can switch my smaller tires onto my blue labels. Then ill just keep the stock rims with my new drag tires as a back up.

Right now, how both setups sit, they both weigh a hair under 10lbs per each tire/wheel.


Nice!!!!

I just got some drag cut razrs for mine.

[cheater13]

Nice!!!!

I just got some drag cut razrs for mine.

Rears? What's your front tire setup weigh john? After I get mine built to a 427 12.5:1 and some other stuff done by 400exshop, hopefully my snows will still hook, haha.

[JOHNDOE83]

Rears? What's your front tire setup weigh john? After I get mine built to a 427 12.5:1 and some other stuff done by 400exshop, hopefully my snows will still hook, haha.

drag cut Razr rears.

Not sure what the fronts weigh, its just some gforce gp alloys on there now.

My 4snows spining down the track in 5th gear with no traction still run faster then any other quad at my track.....lol.

so your 4snows are fine for now.

http://i953.photobucket.com/albums/ae15/johndoe83_2010/CAM00949_zpsabe3062f.jpg (http://s953.photobucket.com/user/johndoe83_2010/media/CAM00949_zpsabe3062f.jpg.html)

[cheater13]

Oooo looks nice. Let me know how they do when you race again. I have 2 sets of razrs. I don't really care for them though. They're not drag cut though.

But good. I was thinking of trying my Dunlop rears but not sure if I want to take the chance. They only have about 65% tread too.

You sure have a lot of air in them things. How many psi are you running? I run around 3-4 in my snows.

[JOHNDOE83]

Oooo looks nice. Let me know how they do when you race again. I have 2 sets of razrs. I don't really care for them though. They're not drag cut though.

But good. I was thinking of trying my Dunlop rears but not sure if I want to take the chance. They only have about 65% tread too.

You sure have a lot of air in them things. How many psi are you running? I run around 3-4 in my snows.

Tried to race saturday night with them but after the big alcohol trucks went down the track the ruts were as deep as my front tires...lol. So I couldnt race, theres no way I could hit the rut at speed and survive.

The cut razrs are best for wet dirt tracks "like sat night" they hook better then the snows do and have better gearing ability then the paddles do, I can run 14/36 instead of 14/42 and use a 20in tire. Keep in mind my hybrid roosts them down the track spining the whole way so my stuff performs slightly different then yours. But if you have old ones laying around, I made these in 1 hour with a $20 harbour freight tool...lol.

I run anywhere from 3-10 psi depending on situation.

[cheater13]

Yeah I have two sets because my one set got a slit in the sidewall. Have to keep them pumped up to 6-8psi or the plug will blow out when I do donuts, haha.

But if I knew as much as gears as you did, I would have a whole shelf of sprockets. I think my 13/40 setup works pretty good for me. Got me the best times so far on the 250-275ft track. Not sure what I would do for 300-500ft though.

I want to keep my snows and put .125s on them. Also, I want to try the ohtsus and Dunlop tires on our track someday. People said them things hook hard too. But my snows did killer on the wet track last year. Everyone else spun. :D

My fronts on the other hand.... No. Had to get off the 400 and turn it with manpower, lol.