Should I hop up my EX?

[Rkangel7]

My '99 EX runs well, so I have no real reason to crack open the motor. It has the big three, but I still find that I have to ride harder to keep up with the other quads in the group (almost all are 450's or bigger).

I like the reliability as well, but I'm also at a crossroad. Do I put money into the 400ex's motor and suspension (yet possibly lose reliability from the motor mods), or put that money toward a newer quad with newer suspension and technology.

Thoughts anyone?

[honda400ex2003]

Why not to some of the smaller stuff to it. i am not sure what the big 3 are but i assuming they along the lines of exhaust, tires, and susp. I have never heard of that. you could do a sparks key, and a few other cheap mods plus if you are riding woods alot you can go down a tooth on the front sprocket to make it accel better but you will go slower. this may help to keep up to the 450 in the woods easier but will hurt on the fields and such. otherwise the next step is go into the motor or get the best susp you can to help make it easier to go faster. steve

Originally posted by honda400ex2003
Why not to some of the smaller stuff to it. i am not sure what the big 3 are but i assuming they along the lines of exhaust, tires, and susp. I have never heard of that. you could do a sparks key, and a few other cheap mods plus if you are riding woods alot you can go down a tooth on the front sprocket to make it accel better but you will go slower. this may help to keep up to the 450 in the woods easier but will hurt on the fields and such. otherwise the next step is go into the motor or get the best susp you can to help make it easier to go faster. steve

Big 3 is Exhaust, Filter, And Jetting.

It's more commonly used on EFI quads, that term, for exhaust, filter, and programmer.

This situation depends. Are you happy with the 400ex? Is it just power you feel your lacking? I would try a couple things.

A curtis sparks timing key, and a hotcam stage 1 with the xr400 head gasket.

[F-16Guy]

Unfortunately, you're not going to get much out of it, maybe $1500, so realize that you're going to be paying a chunk of change out of pocket for a 450.

Are you a good mechanic? If you're fairly capable, then the 400ex is a good engine to cut your teeth on. You can do some pretty extensive mods without sacrificing reliability IF you do the correct mods. For a reliable 400ex that will run pretty closely with the 450s:

-- 11:1 87mm (416cc) piston. JE or Wiseco are both good, inexpensive options.

-- HotCams Stage 2 cam. A drop-in cam that requires no additional mods for compatibility.

-- GT Thunder head studs. I don't care what anyone says; these are a MUST for a reliable 400ex build. Don't cheap out on this.

-- OEM XR400R top end gaskets, or a Cometic set with the MLS (multi-layered steel) head gasket. Stay away from fiber head gaskets.

My advice would be to buy the parts (piston, cam, gaskets) from the cheapest place you can find, and then send the new piston and cylinder to GT Thunder and have them install their HD stud kit and bore and hone the cylinder for the new piston. When you get the cylinder back with the studs and fresh bore, it will be ready for assembly. Depending on how things look, it may also be a good idea to send the head in also to have the valves and valve seals done. You may also be able to have that done locally for a reasonable price, and avoid paying to ship the head.

[Snipe]

How much would all that run?

[Rkangel7]

Yeah, by big three, I meant that my 400 has a pipe (White Bros E-series), Filter (K&N with outerwears), and jets. Sorry about the confusion. I've been spending some time in the fuel injected quad forums lately. ;)

I ride mostly dunes and sand trails. Our riding group is made up of quite a few KFX450's, Raptors, and a couple LTR's. I like the 400ex. Just looking for ways to reliably keep up without having to work so hard doing it. This last trip out the dunes showed some of my limitations in both power and suspension. There were a few dunes I had to go around rather than follow everyone else over, the front shocks were reaching their limit in the rough stuff, and for some reason I was pushing sand like a bulldozer.
Motor-wise there is not much more I can do without opening it up...besides a cam. It is the potential cost of both the motor and the suspension work that got me thinking about the possibility upgrading.

Hypothetically, for those who have done something similar, if I was to do the 416 kit with Hotcam, cam chain, valve refresh, HD studs and labor, new a-arms and decent front shocks...about how much would I be looking at?

[honda400ex2003]

cool thanks for clearing up the big 3. I guess it makes sense now. lol, steve

[F-16Guy]

Originally posted by Snipe
How much would all that run?
Probably close to $500 w/ parts and machining, assuming you do the tear down and assembly.

--Piston w/ gaskets, $160
--Cam, $140
--Studs (installed) $110
--Bore & hone, $80
--Jets, $10

Give or take a little, but look on eBay and shop around at the popular places. There are good deals out there, but you have to look for them.

[MyKe2g3]

If you want to somewhat keep up f16guy gave you some good advice. As far as reliability goes it all depends on if whos doing the wrenching knows what to do. You can get a 440 kit and keep up with the others if the guy building it has a clue. As far suspension goes just get some 450r shocks read the sticky and maybe pick up some a arms and this will make you handle better.

[brothers]

Just read the post and it got me thinking so i went on ebay and found this. It seems like a great deal. they have more on there just search trx400ex and you will get pages of parts.

http://cgi.ebay.com/ebaymotors/HONDA-TRX400EX-440CC-89MM-BIG-BORE-CYLINDER-440-400EX_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a2 Q7c39Q3a1Q7c72Q3a1240Q7c240Q3a1318Q7c301Q3a0Q7c293 Q3a1Q7c294Q3a50QQ_trksidZp3286Q2ec0Q2em14QQhashZit em53db6519eeQQitemZ360163121646QQptZMotorsQ5fATVQ5 fPartsQ5fAccessories

[F-16Guy]

That seems like a good idea, but I would never put a piston in a cylinder that wasn't bored specifically for it. Most good shops won't bore a cylinder unless they have the new piston for a reference. There are variances in manufacturing, and you definitely want the cylinder to be bored and honed to fit the piston you have.

[Rkangel7]

So, if my figures are right I'd be looking at $1200 to $1500 to do the motor, shocks, and a-arms, (depending on the components used) correct?

On average what kind of power increases would a 416 get you?

[BamBam730]

Rkangel7,
Just rememeber that no matter what mods you do, the machine is 10 years old.

[brian76708]

Originally posted by F-16Guy
Probably close to $500 w/ parts and machining, assuming you do the tear down and assembly.

--Piston w/ gaskets, $160
--Cam, $140
--Studs (installed) $110
--Bore & hone, $80
--Jets, $10

Give or take a little, but look on eBay and shop around at the popular places. There are good deals out there, but you have to look for them.

dont forget you still will need
definitly these first 2
+crf 450 cam chain $50
+cam chain tensioner $60
i would recommend redoing your head since its a 99 and at least get valve seals we all know there probably bad.

+Valves/ seals / springs- around 150 200
not to mention labor if you couldn't do it your self.
and depending on suspension you can spend anywhere from $100to 200 for just 450r front shocks and if you plan on getting a arms that will be another $400 on up

[Rkangel7]

Originally posted by BamBam730
Rkangel7,
Just rememeber that no matter what mods you do, the machine is 10 years old.

See, that's the other reason I've thought about possibly putting that money toward a newer quad, and why I'm at a crossroad.

The EX has good ergonomics. It is in good shape for a '99. And right now it runs fine. It doesn't smoke, the bearings still appear to be in good shape with no play or wobble. But, like you say it is 10 years old and who knows what you'll find when you start getting into things (especially since I'm not the original owner). I know as soon as I start taking it apart I'm in for the long haul.

Hearing some of the horror stories about used 450's, I'm little cautious about going that route. Although several of the guys I ride with have KFX450's and put a lot of hours on their quads. One has over 600 hours on his original top end. His dealer checks it every time he takes it in for a service they swear that it is still in great shape. He may have one of those freakishly-well-assembled quads, who knows... Either way that's pretty darn reliable. Of course there is also the Raptor 700.

I guess I'm just thinking out loud.

[RIDEREDson]

I know C&D racing gave me a nice quote including labor. All you gotta do is send in the top end and stuff.

Even with a 3 angle valve job and port and polish it was under a grand.

[416exman21]

trinity racing does good work for port and polich and multi angle valve job$450---my 416 is quick and worth what i got in it and still very reliable (never left me stuck in the woods)in trails and drag mine will smoke 450's all day and not unless they are built really stupid but as far as the basics and a cam ...i got them...416 or 426 is the way too go .

[RATPACK Z400]

Your machines 10yrs old ,Id sell why you can and get 450 ,not worth money IMO if your a diehard honda freak ,wait till the new 450r comes out! or get used 450 thats in good condition you could buy used 450 with all the goodies for cheaper than motor/sus work for EX .I know Im going to hear it now from the EX guys ,but thats the facts .theres guys getting 450s for $3000 -4000 you would put that in Ex buy the time your done !These guys that say big bore ex will beat 450s are full of it unless they have drag motors/trans a regular big bore will get smoked by 450 there riding agains,t less skill riders to beat 450sIMO.

[F-16Guy]

Originally posted by brian76708
dont forget you still will need
definitly these first 2
+crf 450 cam chain $50
+cam chain tensioner $60
i would recommend redoing your head since its a 99 and at least get valve seals we all know there probably bad.

+Valves/ seals / springs- around 150 200
not to mention labor if you couldn't do it your self.
and depending on suspension you can spend anywhere from $100to 200 for just 450r front shocks and if you plan on getting a arms that will be another $400 on up
The bike is a '99. I'm talking about a bare-bones build here. Depending on the condition of the head and valves, he could opt for just a set of valve seals and a lapping -- or he could just leave it like it is if he doesn't have any problems now.

The cam chain and tensioner are also optional as far as I'm concerned. If he wants to be safe, an '02 CRF chain is $32 from Service Honda. I've got 10 years of riding on my original tensioner with zero problems. If it's installed properly, there should be no issue with re-using the old tensioner.

So you have the build at about $500-600, a-arms for about $200-400, 450R shocks for about $150-200, and a pair of G-Force extended hubs for $80.

Total build with suspension and engine costing roughly $950-1300. That's a pretty substantial difference from the $2500-3500 he'd be out-of-pocket for a 450R. Not to mention he'd probably have to do some repair/upgrading on that.

It could really go either way, but if the 400ex was well taken care of, then getting it to where it needs to be might save some cash.

[BD444]

I completely agree with F-16.
The fact that is ten years old mean nothing. The may be some parts that need replaced. The cost of a 450 isn't ridiculous, however you would also have to put parts on the 450 as well. The upkeep on the motor is also a much higher cost. NEVER buy a used 450....who knows how the maintenance was. Overall, follow F-16 bare bones rebuild and go for it.

[BEAVER.989]

Don't be afraid of the fact that it's 10 years old if you like it. The newest 250R's are 20 years old and plenty of people are still willing to dump money into them.

[F-16Guy]

Hey Rkangel7, how about some photos of the ex? Maybe we can see what condition it's in and give you a better idea of whether it's a good idea to spend money on it. I'm curious to see what it looks like. I have a 2000 400ex, and it's really clean, so you can't judge a quad solely by how old it is.

[Rkangel7]

Here are a couple pictures. They are from a camera phone though...

http://img35.imageshack.us/img35/8559/400exmy.jpg

http://img35.imageshack.us/img35/4671/400ex2.jpg

[nakomis0]

Not sure what type of riding you do but why don't you just put suspension on it and drive it till it blows up or till your ready to sell and upgrade. A good thing about suspension is it holds its value pretty well, just keep your stock stuff so you can put if back on the bike when you get rid of it.

Thats a clean looking 99. Looks good.

[416exman21]

Originally posted by RATPACK Z400
Your machines 10yrs old ,Id sell why you can and get 450 ,not worth money IMO if your a diehard honda freak ,wait till the new 450r comes out! or get used 450 thats in good condition you could buy used 450 with all the goodies for cheaper than motor/sus work for EX .I know Im going to hear it now from the EX guys ,but thats the facts .theres guys getting 450s for $3000 -4000 you would put that in Ex buy the time your done !These guys that say big bore ex will beat 450s are full of it unless they have drag motors/trans a regular big bore will get smoked by 450 there riding agains,t less skill riders to beat 450sIMO.



your dumb- big bore 400 will smoke a 450r --i do it all the time and mines 416ex -the 440 will wack it - and for the z400 fuel in jection (smoked that too) - 450r are quick but u will put the same amount of money in either 1--- u have your 400 keep it and hop it up a little it will be pleaty worth it----it's like a drug buying upgrades....

[lyrikz74]

RKangel, im in your EXACT spot. Went to the dunes this weekend and there were hills that i couldnt get up that everyone elses 450 was making.... My issue is mine is a ****ing 08 and i JUST bought it a few months ago. I rode my buddies 450 and am just BUMMED> Mine is a stock 400ex....

Not trying to hijack to badly, but what can i do to get this thing to keep up with some of those 450s or should i just trade it in right now and step up??? My 400 is stock. First thing i want to do is get better paddles and some 450 front shocks. I dont want to bother if theres no way i can get this thing to keep up.... An example is the 450s were heading up hills in 3rd gear. I was 2nd the whole way up....sometimes having to hit 1st..

[Rkangel7]

Originally posted by lyrikz74
RKangel, im in your EXACT spot. Went to the dunes this weekend and there were hills that i couldnt get up that everyone elses 450 was making.... My issue is mine is a ****ing 08 and i JUST bought it a few months ago. I rode my buddies 450 and am just BUMMED> Mine is a stock 400ex....

Not trying to hijack to badly, but what can i do to get this thing to keep up with some of those 450s or should i just trade it in right now and step up??? My 400 is stock. First thing i want to do is get better paddles and some 450 front shocks. I dont want to bother if theres no way i can get this thing to keep up.... An example is the 450s were heading up hills in 3rd gear. I was 2nd the whole way up....sometimes having to hit 1st..
What dunes do you ride?

[lyrikz74]

Whinchester bay. Oregon. Sandlakes, that sorta thing...

Im looking at getting the following
1) smaller front sprocket (down one tooth)
2) sparks timing advance flywheel key
3) full exhaust
4) rev box
5) new filter with no lid. Any recs on what filter to run???

Originally posted by lyrikz74
Whinchester bay. Oregon. Sandlakes, that sorta thing...

Im looking at getting the following
1) smaller front sprocket (down one tooth)
2) sparks timing advance flywheel key
3) full exhaust
4) rev box
5) new filter with no lid. Any recs on what filter to run???

I know you're going to hate to hear this, but in my opinion it sounds like you need a different quad.

It seems like you ride mostly dunes, and no matter how hard you try, it will still be an outdated air-cooled 400ex. Sure, you can make it move alright in the sand, but without some serious modifications it's NEVER going to climb dunes like the 450's and banshee's.
I would say either look into a 450, or find a banshee so you can have some cash left over. Both of those bikes are dune beasts, and liquid cooled.

But if you do stay with the 400ex, a full exhaust, timing key, filter, and 450r carb I guess would make it some what livable. And forget the rev box, they do nothing, and a 400ex will never rev to 10,100rpm. They stop making power at about 7500 lol.

[Rkangel7]

Originally posted by lyrikz74
Whinchester bay. Oregon. Sandlakes, that sorta thing...

Im looking at getting the following
1) smaller front sprocket (down one tooth)
2) sparks timing advance flywheel key
3) full exhaust
4) rev box
5) new filter with no lid. Any recs on what filter to run???

Small world! We were just at Winchester Bay a week ago. That's where I was having problems keeping up with the 450's and Raptor 700. Especially on the large dunes and tree shots on the east side.

Currently I'm running stock gearing (which is 15/38 for the '99), but can definitely see the advantages of a smaller front sprocket for the hills.

[lyrikz74]

Thanks for that info. Its sad to think my 08 is outdated. ahaha.. What has me bummed is i had a 01 400 that had a pipe on it and a rev box and i never really had issues going anywhere... Is it that 35lbs that reverse adds thats holding up my 08???

[dariusld]

What happens if you do all this work, then wish you had gotten or still want a 450. I say get the 450, even though I love my 400.

[lyrikz74]

Originally posted by dariusld
What happens if you do all this work, then wish you had gotten or still want a 450. I say get the 450, even though I love my 400.

Thats the thing, i loved my old 400. It never got stuck, it went anywhere.... I think my paddles suck *** to... I will be upgrading that...

Say i did the sprocket, timing key advance, exhaust, filter w/nobox, new good paddles. You think i would be able to keep up better then i have been? I dont have to race and win anyone. Just the fact i couldnt get up a hill that the 450s could REALLY bugged me.... I always went where the 450s went before, now i have a new bike and cant go anywhere.... I just paid 5500 otd for the 08 and have ridden it once and regret it.

Originally posted by lyrikz74
Thanks for that info. Its sad to think my 08 is outdated. ahaha.. What has me bummed is i had a 01 400 that had a pipe on it and a rev box and i never really had issues going anywhere... Is it that 35lbs that reverse adds thats holding up my 08???

LOL Where the hell did you get 35lbs from? The reverse barely adds ANYTHING. The 08's, are the same as all the other past 400ex's weight wise. That 410lbs they show in the site, is wet weight. They used to show dry weight. So no, that's not holding you back.

I will say, there was quite a difference in power on my 400ex with the exhaust. Makes it a different animal. The stock exhaust is super restrictive on the 400ex's. Don't like to rev out.

[lyrikz74]

Originally posted by DMC-4OOEX
LOL Where the hell did you get 35lbs from? The reverse barely adds ANYTHING. The 08's, are the same as all the other past 400ex's weight wise. That 410lbs they show in the site, is wet weight. They used to show dry weight. So no, that's not holding you back.

I will say, there was quite a difference in power on my 400ex with the exhaust. Makes it a different animal. The stock exhaust is super restrictive on the 400ex's. Don't like to rev out.

The weight between the reverse and no reverse 400's is like 30lbs... Unless they changed the way they weight them like you were saying.

My old 400 never lost power in second, ever. This one loses power in second all the time. ahaha.. So i think you mentioning how it doesnt like to rev out maybe the exhaust will fix it...

I figured i would spend about under 300 bucks for all that stuff and im hoping i will like it. I know its not going to turn it into a 450, but i just want it to not dye out in second, and maybe let me to pull some hills in third...

[espergre]

If you are mechanically inclined, and wrench yourself. For real cheap you can find a stage 1 or 2 hotcam, 11:1 stock bore wiseco piston, air box lid off, uni or K&N filter, either one get an outerwear if riding in sand. Any exhaust system is going to have the biggest difference over a stock exhaust without its baffle removed. Get an hmf slip on, cheapest pipe with big ganes.

But you mentioned you feeling like your pushing sand like a bulldozer.... take a look at your tires man, sand paddles in back are great, but a set of front sand tires will help tremendously for floating over sand and turning. Stock tires are heavy and the knobs grip the sand way too much. I would start with those and see how your stock quads feels in the sand, you wont regret that purchase for a dedicated duner.

I have a 450 myself, but i started off on a 400. With just a 11:1 piston, cam, full hmf exhuast, and uni filter, a good rider can outride most 450s, even in a drag race. (notice the good rider part) These mods will bring you up to the power of a 450, but will not surpass by much like people claim. Any 450 with the same simple mods, cam, piston, filter and exhaust WILL outrun any similiar 400. To this date, my girl races my 400 and spanks many guys on stock or slightly hopped 450s and embarrasses them. Rider skill has way more to do with a 400 beating a 450 than the engine does. PRACTICE. I havent found a hill yet that the 400 cant power up, let alone wheelie up if youve got the skillz

[F-16Guy]

I raced my buddy's stock 450R up sand mountain and had no problem beating him. Once he added the HRC kit, he was able to pull me, but not by more than a couple of bike lengths, and sand mountain is a long pull. Putting in the mods that were suggested will make a huge difference in pulling power for a relatively small investment. You probably won't be smoking anyone up the dunes, but you will definitely be able to hang.

[Rkangel7]

I'm not a drag racer, so embarassing 450's isn't my goal. Athough there is a certain appeal to having a sleeper quad...

Good handling, power, and reliability are what I'm looking at for a good all-arounder. Long term reliability is one of the reasons I have not been completely sold on 450's. Although 600 hrs on a KFX 450 had started to change my mind.

Assuming I do the 416 kit, and stage 1 hotcam, what jetting would I be looking at for just above sea level?
Should I consider 10:1 or 11:1 piston? Would I lose some low end if I went with a stage 2 cam? Would I have to pull the motor to do the kit, or can I do it on the bike?

What are a decent quality set of affordable +1 or +2 a-arms?

F-16, how do you like the Lexx pipe? I have a White Bros E-series and it's a challenge to meet the 93 db noise restrictions in many of our riding areas.

Thanks again for all the info, guys!

[MyKe2g3]

Ever heard the statement go big or go home. I think you'd be more inclined to get a 440 kit with stage 2 cam along with a good pipe will get u closer to where you want to be. You will be around 40 hp which would be plenty quick enough to deal with stock 450s. As far as aarms decent and affordable dont usually work together lol. If you get a chance check out this months Atv action they just put a 440 kit on their bike using ct parts and it woke it up.

[killer400ex]

Originally posted by F-16Guy
Probably close to $500 w/ parts and machining, assuming you do the tear down and assembly.

--Piston w/ gaskets, $160
--Cam, $140
--Studs (installed) $110
--Bore & hone, $80
--Jets, $10

Give or take a little, but look on eBay and shop around at the popular places. There are good deals out there, but you have to look for them.

piston with gaskets from wiseco (assuming that you bore up) starts at 200,
and installing studs arent really necessary, ive seen 440 strokers run with stock studs for years and never run into a problem, althogh it is a good precaution

[lyrikz74]

Rkangel.... Its like im writing your posts.ahaha Thats how i feel about my quad....

IM going to try these mods and hopefully it gets me to where iw ant.

[lyrikz74]

And if that doestn work, i will put a cam in it and rejet it and im sure i will be good there... I just want to keep up with a 450.... or even relatively close.

[Rkangel7]

Originally posted by lyrikz74
Rkangel.... Its like im writing your posts.ahaha Thats how i feel about my quad....

IM going to try these mods and hopefully it gets me to where iw ant.

Great minds :)

I'm considering a few additional hop ups, maybe a 416 just so I don't fall behind so easily.

I think a 440 kit is a bit overkill for a simple budget project. I would have to address reliability, cooling, HD studs, a cylinder re-sleeve, case machining, carb replacemet or modification, and probably head work...which I wouldn't mind doing if I was planning on completely rebuilding my quad. But if I was going to do all that to get 450-like power and suspension, why wouldn't I just get a 450?

[dariusld]

Then if you do all that and have any problems, your'e really going to wish you had gotten the 450:)

[lyrikz74]

Im with you.. I will literally follow what you do... Im not worried about the suspension yet...

Going to do the sprocket, the timing key, exhaust, and filter with no box.... and new paddles...

What are you gonna do?

[lyrikz74]

He wont have any problems.

[Rkangel7]

The first thing I'm going to do is check my compression to make sure I don't have any ring problems or cylinder wear that could be causing lost power (as soon as I can get the right adapter for my compression tester, that is).

I don't really want to tear down the motor if it's in good shape. So, if the compression is good I'll probably spring for a Stage 1 hotcam, rejet accordingly, maybe tweak the gearing and see how she responds along with the filter and pipe that I already have.

If the compression is iffy, then I may consider a budget 416 build.

The suspension will probably wait for now, but front sand tires are definitely on my list.

[RATPACK Z400]

416 dude get real you beat some less skilled riders and claiming your quads a 450 killer Please! the 450s with exshaust /filter put out way more than you got, whats your hps -like 32hp ? the reason I say get 450 is that he rides dunes 400exs wont keep up without thousands of dollars put in it to say 440/416 will beat 450 is a joke ,unless there set up to drag only. THATS NOT DUMB ITS THE FACTS!

[dariusld]

Originally posted by RATPACK Z400
416 dude get real you beat some less skilled riders and claiming your quads a 450 killer Please! the 450s with exshaust /filter put out way more than you got, whats your hps -like 32hp ? the reason I say get 450 is that he rides dunes 400exs wont keep up without thousands of dollars put in it to say 440/416 will beat 450 is a joke ,unless there set up to drag only. THATS NOT DUMB ITS THE FACTS!

My friend has a exshaust /filter 450 and we are dead even up the hill and at the drags and he is a better rider than me. Those are the facts in my case:rolleyes:

OK... Enough I beat he beat she beat. The fact is, no matter what someone rides, they're always going to defend it. Personally I hear so many stories from so many people, people that I know, that aren't true. They have more stories then mother goose, and I'm sure there's a bunch of people like that on here too.

Here's my honest view on the whole 400ex vs 450 debate. My 400ex, I will say, is pretty snappy with the full exhaust, filter, and sparks key. One of the faster 400ex's I have rode out of other piped 400ex's. My dad's good friend, who we ride with a lot, has a 2007 YFZ450. All it has is a HMF exhaust, rev box, filter, and cam mod done.

There's a main strip at Freeland, where you can really open stuff up. I ripped down it on my 400ex (This was before my banshee was finished) and got a good idea of speed. I thought it was decent.

I hopped on that YFZ450 for the first time since he got it on hard pack ground. And all of you "My 400ex will beat a 450" guys will be pissed, but I'm sorry. There is NO competition. That 450 got up and went like no ones business. It absolutely embarrasses the 400ex. I got back on the 400ex and was like wtf, this thing is amazingly slow. The 450's just pull to top gear like no ones business and has a ton of torque.

Even I admitted it would definitely give my banshee a good run for it's money.

So guys, the 400ex, is a GREAT bike. It's super reliable, and a great trail beater. But all you dreamers that think you can spank a 450, well guess what. They throw an exhaust and cam on that 450 and it will wipe the floor with your 440 stroker. The 400ex is not meant to be a race bike.

[RATPACK Z400]

Im not going to argue anymore on this 400ex beating 450 BS! the guy being talked into building an ex to keep up with hes friends 450s and will probably spend thousands trying when he could (if funds let him) buy 450 and problem solved ! thats the way IMO he should do. then in future he can make faster when he becomes more skilled rider but spending thousands on EX is retarded ! I see it all the time people trying to talk others to spend thousands on Ex than just getting a 450 it a waste unless you are diehard Ex fan,Exs are good trail quads but in dunes they stand no chance against 450s unless your a super mechanic with bottomless pockets!

[Rkangel7]

I could always get one of these. :D

http://img7.imageshack.us/img7/9941/780sideview3.jpg

Sorry, just thought we could use a little levity.

All the input is helpful. Don't worry guys nothing is set in stone yet.

So, having looked at the dune-ability of the 400 and having heard the reasons why I should upgrade, and the reasons why I should not upgrade the EX, what about the flip side: the trail-ability and reliability of 450's? The reputation is that 450's are maintenance queens and require frequent rebuilds. I'm sure there is a certain amount of myth, truth, and rumor to that, but reliability is important. I don't mind maintenance but I also don't want to spend more time fixing and adjusting my quad than I do riding it, if you know what I mean. :)

Originally posted by Rkangel7
I could always get one of these. :D

http://img7.imageshack.us/img7/9941/780sideview3.jpg

Sorry, just thought we could use a little levity.

All the input is helpful. Don't worry guys nothing is set in stone yet.

So, having looked at the dune-ability of the 400 and having heard the reasons why I should upgrade, and the reasons why I should not upgrade the EX, what about the flip side: the trail-ability and reliability of 450's? The reputation is that 450's are maintenance queens and require frequent rebuilds. I'm sure there is a certain amount of myth, truth, and rumor to that, but reliability is important. I don't mind maintenance but I also don't want to spend more time fixing and adjusting my quad than I do riding it, if you know what I mean. :)

They aren't that hard to trail ride. They have massive mid-range torque. The KFX is one of the best "trail" 450's.

Reliability, well if you maintain it, it will still last a while. You just need to adjust the valves more often, change the oil more often, etc. As long as the mods are minimal it will be fine. But once you start getting big bore and such, they're ticking timb bombs.

[F-16Guy]

Originally posted by Rkangel7
...I don't really want to tear down the motor if it's in good shape. So, if the compression is good I'll probably spring for a Stage 1 hotcam, rejet accordingly, maybe tweak the gearing and see how she responds along with the filter and pipe that I already have...

If you decide to go this route, here's a thought (and this has been done successfully with good results and reliability):

Buy a new OEM XR400R or 400ex head gasket. Take that new gasket and drill out the rivets that hold the layers together. The top and bottom layers are the gasket portions, the middle layer is just a spacer to adjust thickness (which is what makes the XR and EX gaskets different). Take the top gasket portion and spray both sides with 3-4 coats of high temp, flat black BBQ spray paint, let it dry, and then reinstall the head with the single layer.

This does a couple things: It raises the compression ratio quite bit more than just switching to an XR gasket. It retards cam timing slightly, which moves the power up in the RPM range slightly, which would be fine (maybe even benificial) with a stage 1 cam. It also effectively raises the deck height of the piston by decreasing the amount of space between the top outer edge of the piston and the corresponding surface of the head. That gap is known as the squish band, and is known to be too thick on the EX. Thinning out the squish band causes the fuel/air mixture to be more effectively pushed into the middle of the combustion chamber just as the piston reaches TDC, which creates turbulance, concentrates the mixture, and results in a more explosive and powerful combustion.

http://www.motorcycle.com/images/content/How-To/Fig_02.jpg

Back in the day, a lot of 440 owners that foud out that their Wiseco 89mm flat top pistons had a lower compression ratio than advertised used this mod along with eliminating the base gasket as an alternative to decking the cylinder to acheive the proper squish and compression ratio.

The end result will be a more powerful, efficient, and cooler running engine for about $15.

[Rkangel7]

What is the reason for painting the head gasket?

Also how do the KTM motors (such as in the Outlaws, etc.) compare in maintenace and reliability to the "traditional" 450's? I've been reading that they have a broad powerband, more low end torque and deliver power differently compared to many 450's.

[RIDEREDson]

A 400 will take thousands to beat a 450 in a drag or where their is a lot of straight aways. But its possible to beat 450's on a mx track with just a 416 and good suspension. People do it. I doubt in A class but B and especially C.

[timmy400exfast]

id have to agree with RIDEREDson

[F-16Guy]

Originally posted by Rkangel7
What is the reason for painting the head gasket?

Also how do the KTM motors (such as in the Outlaws, etc.) compare in maintenace and reliability to the "traditional" 450's? I've been reading that they have a broad powerband, more low end torque and deliver power differently compared to many 450's.
I don't know that the pain is absolutely necessary, but that's what was used as an extra sealing measure. You could probably also use some Coppercoat.

I don't know how KTM engines are as far as reliability, but I rode a 525 bike when they first came out, and it was ridiculous. They definitely make strong power.

[timmy400exfast]

i had a 2002 ktm 125 power and reliabilty man

[RATPACK Z400]

Wow! thats the gayist quad ive ever seen whats it Russian? haha .thats the funniest quad Ive ever seen who was it made for sreech from saved by the bell!

[killer400ex]

you could do all of this or you could just put a wiseco 11:1 comp piston in, also boring up would deff increase your power, even slightly changing your bore size is extremely noticeable, i had a 416 and i bored up to 426 and the power difference was obvious, you could dance around it all you want with the timing keys and stuff but it all comes down to changing your displacement, sure you will notice a big diffrence with the exhaust but nothing is going to increase your chances more than boring even if slightly and increasing compression, im extremely happy i did, and keep in mind that a 440 needs re-sleveing and thats not cheap, also a 440 takes longer to reach higher revvs, i think out of all the diffrent piston sizes ive ridden on 400ex's that the 426 is the best all around, produces a ton of power while allowing you to rev real quick which is good especially in the dunes, and you can also try using a 450r carb, that will also make massive power gains

[Rkangel7]

So, if I was to do a piston would I have to pull the whole motor, or could I just pull the head and cylinder?

[killer400ex]

just the head and cylinder, it took me 30 mins to do a piston rebuild