Winter Project

[99RED4X4]

Well I've had my 400ex for two years now and I'm finally ready for some power. Like everyone else, I ride with a bunch of 450's and 2-stroke 250's. Its time for some more power. Now unlike everyone else, I'm not looking to beat a 450, I'm just looking for a moderate power gain.

My riding is basically tight woods trails and big big hills. All things considered, I want more power, but not just a big top end increase. I really want a nice increase from bottom to top. It seems to me that most engine mods just increase mid/top end power.

Currently I'm on a stock motor, UNI-Filter, 142 Main jet, and FMF Powercore 4.

For my winter project I was thinking about:

Higher Compression (staying at 400 or 416)

Cam (XR or HotCam Stage 1)

Valve job w/ porting

And an ignition module for stronger spark.

Appropriate jetting

All of this is well within my budget. I'm just not sure of the power increase I will get.

Comments/Suggestions? Should I do more/less?

[riotact]

I would also add a full exhaust,450r carb,and open airbox.I am also on a stock motor that has never been rebuilt and that made a huge increase.I would look into suspension before I tore into the motor.

[CJM]

I have a 416, 11:1, open air box, uni filter, slip on, hotcam stage 2, jetted, HD studs and lemme tell you what-it absolutely rips.

My buddy has a totally stock 07 and he was several lengths ahead of me and I just hit it and he went all out and I passed him with ease.

I like the 11:1 b/c you get closer to the true compression your supposed to have, the stage 2 cam really hits mid and low well too and the open airbox makes it breath so much better.

[mineralgrey01gt]

Originally posted by CJM
I have a 416, 11:1, open air box, uni filter, slip on, hotcam stage 2, jetted, HD studs and lemme tell you what-it absolutely rips.

My buddy has a totally stock 07 and he was several lengths ahead of me and I just hit it and he went all out and I passed him with ease.

I like the 11:1 b/c you get closer to the true compression your supposed to have, the stage 2 cam really hits mid and low well too and the open airbox makes it breath so much better.

i had pretty much the same set up but with a 450r carb and it did rip pretty good

[99RED4X4]

riotact - I agree with you, suspension/brakes are always more important than power. You can only go as fast as your bike can handle or and stop.

Currently I have works triple rate front shocks, and a PEP revalved/resprung rear shock. In addition, I have replaced ALL suspension bearings (swingarm, shock, linkage, a-arm, wheel, steering stem)

For what I'm doing with the bike, the only other thing I'd love to have is a 1.5" extended swingarm. Unless I can find a used cheap one, that's outta my budget.


CJM - What you said is what I wanted to hear! I've always been under the notion that higher compression and wild cam's just load a motor with top end power, and leave the bottom end lacking. When I climb hills I like to have that wicked bottom end to help me out if I F**k up...

I already have the UM Racing Oil tank (snapped to bottom off the stock one changing the oil). Being that I have this, would I need a larger oil cooler? I know that heat is a big problem with high compression and 400ex's

[CJM]

The stg 1 cam might be more torquey, for me with the 416, stg 2 and 11:1 I have no problem with power at all imho. Im just using 93 pump gas as well and have (yes I know people say they suck) dyno jets.

I went to some local dunes/pits this past sunday and found it had so much power that even tho my tires (kenda klaw XC) work well in the sand, it slid quite readily from to much power and I had no issues getting it to move in loose sand. Paddles woulda helped but meh it did the job.

Really for me, once you get into the mid rpm its crazy, but low end is def there. My buddy who tuned it for me told me he was pulling wheelies like crazy and was amazed the power vs his mildly build z400.

Personally I just found my setup works well. Im running 20s in the back, 22's up front and the sprockets are stock. I never had an issue with power since I have upgraded. Before even it felt way more powerfull compared to even stock machines (and as far as I know everything was stock besides slip on). My friends 05, and (2) 07's feel like crud even when mine was stock.

Whatever cam you choose or engine combo you will be happy. I let my buddy with the 07 ride mine and he was so impressed hes gonna do the same mods over winter.

Its really hard to say honestly about the cam, b/c I never bought a stg 1 or ride a simialr machine with it either. With the stg 2 I felt gains overall but more so in the upper lowend and when mid hit it was nuts. Higher you went the better b/c of the cam profile, but still-imho it pulls hard always. Face the facts you not gonna be hitting super low RPMs to do any hill climbing either, so of course higher you rev more cam helps. If I so much as blip the throttle while coasting or taking it easy the front wants to lift up.

Hope all that helps :)

[99RED4X4]

CJM, I think I'll take your advice. Sounds like a nice combo!

Riding season is almost over for me, so as soon as I start tearing into it, I'll take tons of pictures and keep posting.

[CJM]

It wasnt a hard job to do honestly if you have taken apart engines before.

Good luck Red!

[99RED4X4]

I was looking at some parts, and thought of something else. I know that I need new valve guides, and I have a bit of ticking. Someone told me the heads are probably worn on my rockers. So during this project, I'm gonna replace some valvetrain parts.

When I was looking at parts, I saw that I can get oversized Intake Valves.

Anyone ever experiment with these? I assume If I was going 440 or 465 these would be necessary, but if I'm just goint 416 with 11.1 will they be benefical?

[matt1106]

i built a 400 for my friend similar to what your talking about, and it was a good setup, tons of torque. It was a 416 with 11:1 compression, Stage 2 hotcam, mild porting, no airbox cover, K&N airfilter, a big gun CDI, and full yoshi exhaust. It would stay in front of my other friends stock TRX450R in a drag race, but in the woods, the 416 was so much better than the 450. Unbelievable torque, u could put it in 3rd gear and just go no shifting, no clutching. Those r the positives. now here r the negatives... When u do these things to your motor, and i dont care what brand stuff you buy or who puts it in, you lose reliability, considerably so. To me its not worth it. one of the best things about the 400, is how bullitproof it is. when u do motor work to it, all ur doing is taking that away. I race GNCC and i dont feel like my stock motored 400 has any disadvantage against the 450's in the woods, its all about the rider...if u ride trails, and ur suspension is setup good there is no reason u should need to do motor work to keep up with ur buddies, unless they can ride better than u ;-)

[99RED4X4]

What kind of reliability are we talking here?

I used to have a banshee, and actually enjoyed always having to work on it (cleaning carbs, adjusting carbs, fouling plugs). I was used to flooding it now and then.

Now obviously this is a 4-stroke we're talking about..
Are you refering to problems like:
Overheating
Not Starting when hot
Stalling
Flooding
Bolts comming loose
Constantly tweaking jetting

Is this what i'd be in for? Or does it get worse?

[mineralgrey01gt]

i didnt have any of those problems you listed you are concerned about. Only thing is just go ahead and put some HD studs in so itll be a little reassurance. Sure it will get a little warmer but not enough to kill the engine as stated before. If I get another 400ex id do the same exact thing i did to my last one and still have killer reliability. You wont regret doing it and whoever says there is enough power in a stock motor is bs'ng because if they ride like that in the woods on a stock motor think of how much quicker you would be with more power and torque in your bike. Just food for thought.

[99RED4X4]

Matt1106 isn't the first person who has told me that once you change the stock motor it will never be the same (as far as reliability). I had another person tell me that once you crack a stock one open, it will never be the same. Something about the factory assembly is superior.

In my case, I'm a maintenance freak and like my stuff to be PERFECT. So when I go ahead and do this, I'll probably replace just about everything that I see.

The one thing that I haven't decided yet is if I should let a shop do all this work, or do it myself. I'm definitely mechanically inclined. I've had every piece on the bike apart besides the motor and had no problem re-assembling it properly, I've swapped motors in trucks, set valves, and stripped down briggs and stratton motors. I have never undertaken a project like this though. I figure if I take my time, follow the manual's (I have to different ones for the same bike), double check everything, and ask questions here on the forum as I go, I'll be just fine.

[CJM]

Matt doesnt seem to have much of a clue or he and his buddy didnt do a good job on thier build or something.

There are tons of us running roughly the same combo with no ill effects at all. I have had mine out at least a half dozen times on the trails and testing it out at my house with no issues.

Heat is the biggest killer, for some in colder climates this may not matter at all or even factor in. For the purposes of heat dissipation I put on a spal puller fan just to be on the safe side and I did the HD studs for the same reason. its totally reliable, not a single issues since I built it.

As far as doing the actual work:
-I had GT thunder do the bore and HD studs
-I uses a wiseco piston, no junk there
-I bought cometic EST (extreme seal technology) gaskets. These are higher end gaskets than even the dealer stuff. They claim they are as good as or better than OE: http://www.cometic.com/est.aspx
-I assembled it myself, im an auto mechanic by trade and have rebuilt plenty of things. I found it SUPER easy to do and I didnt use any special tools really besides stuff you can commonly buy at the store and a socket I ground down to fit the sparkplug.
-I only use quality oils and change often. Some like shell rotella, I prefer mobil 15w-50 and will use nothing less than a syn oil in it.
-I reground the valves (look up how to do it using a drill..works super well)
-Replaces valve seals
-generally I went over everything with a fine tooth comb and made sure it was good. my quad is nothing fancy, it is fast and gets the job done with minimal bling bling parts.

Overall I felt that the little bore job I did will not take away enough material for it to add more heat. Really if you add the fan and run it while your riding it cools it so much better its not funny. Its probably cooler than stock.

[matt1106]

Originally posted by 99RED4X4
Matt1106 isn't the first person who has told me that once you change the stock motor it will never be the same (as far as reliability). I had another person tell me that once you crack a stock one open, it will never be the same. Something about the factory assembly is superior.

In my case, I'm a maintenance freak and like my stuff to be PERFECT. So when I go ahead and do this, I'll probably replace just about everything that I see.

The one thing that I haven't decided yet is if I should let a shop do all this work, or do it myself. I'm definitely mechanically inclined. I've had every piece on the bike apart besides the motor and had no problem re-assembling it properly, I've swapped motors in trucks, set valves, and stripped down briggs and stratton motors. I have never undertaken a project like this though. I figure if I take my time, follow the manual's (I have to different ones for the same bike), double check everything, and ask questions here on the forum as I go, I'll be just fine.

Look i really dont care wat you do, and as far CJM running his mouth about me and my buddy not knowing what im doing i never said i had any probs with my build, we never had a failure...but its a well known fact that doing motor work decreases reliability on a motor..call duncan, racing call CT racing, see wat they tell you.. As a stock motored 400ex sits, they will run forever no matter how bad you beat them as long as you change ur oil and adjust the valves. thats it! If you do motor work, you can count on it not being the last time.

[99RED4X4]

Easy now killer, we're all friends here. No need to get upset. I have my opinions, He has his, and you have your own. Lets not fight over this.

Matt I agree with you, I've always heard that you loose reliability.

CJM I like hearing from you that you did the job correctly, took some extra time to get better parts and have had no problems.

I definitely need more power, and am going to tear into this thing. It must be reliable. I ride in a place called wellsville that is hills, hills, hills. If your bike breaks and you get stranded, your done for. If you leave your bike there, it will get stolen or burnt. Reliability is cruital.

[ish416]

As far as reliability of a 416, I have had no issues with my 416 at 12.5:1 over the last 6 years. It runs just as well as it did when it was stock except with more power. I do not have a spal fan or a larger oil cooler, the cooling system on mine is stock.

The only time you will have issues with a 416 overheating is when it is very hot out ( 100 + ) or if you let it sit and idle for long periods or if you are moving at less than 10mph for extended periods on an extremely hot day.

Some people around here will mix a higher octane fuel during times they know it will be hot. Such as E85 and 93 or race gas and premium. It will lower temperatures in the cylinder. I have even ran leaded AV fuel and it worked fine, although it destroyed the packing in my muffler.

An 11:1 416 setup should be just as reliable as a stock EX. Just make sure that you use HD head studs for peace of mind while running a higher compression. Also, if you run a 400EX gasket you will loose some compression. An 11:1 setup may be more like 10.8:1. Where as an XR400R gasket which is thinner, will get you much closer to the advertised compression ratio. That may have changed with some after market gaskets but it is true for the OEM Honda gaskets.

As far as your setup goes, mine is very similar.

My setup when I first did it was:
12.5:1, XR400R cam, stock header with fmf powercore 4, kn filter, no airbox lid and proper jetting.

That setup had so much torque that I could pull the front wheels up with no clutch in 5th at 25mph with very little help from me. No, that was not standing on the back bar either. My friends and I commonly refer to my EX as the tractor or the diesel because of the amount of off-idle torque.

The only difference I would make with your setup would be to not get an ignition module and instead get an 04-05 450R carb instead.

I think you will be very happy with your setup. A stage 2 hotcam is more mid-to upper rpm power. A stage 1 or XR cam is more low to mid range power with an almost stock feeling top end power.

[99RED4X4]

Hmmmm 11.1 or 12.5.1 That is the Question.

ish416, you speak of not getting the ignition module. The only reason I like these are for the improved spark. I really don't want the rev limiter taken away because in my opinion, you rarely make power past what the stock stops at. Its just a greater chance to over rev and snap the crank or something.

Maybe i'll go with the stage 1 cam.

It seems to be in between the xr400 and the stage 2 cam

Again has anyone toyed with the oversized intake valves?

[CJM]

I went with 11:1 b/c of the fact I wanted to use pump gas only. I couldnt find race gas as easily and of course its much more money.

As for cams, tough call really. I like how mine hits hard on the upper lowend and mids as well as the high (basically the whole range imho). But I didnt have the luxury to try a stage 1 in it to see whats going on or an XR400 cam which is somewhat in between them all. hey, buy one, try it and if you dont like it im sure you can resell it. Rather easy to change out as well.

[ish416]

you speak of not getting the ignition module. The only reason I like these are for the improved spark.

I have ridden EX's and other quads that have had either ignition modules for stronger spark and ones with CDI's that are supposed to advance the timing.

I could not tell a difference between an ignition module or CDI at all compared to a stock machine. They are just a waste of money in my opinion. If it made a noticeable difference, I would have one on my EX. In reference to the rev boxes, the 400EX engines are not your sophisticated high revving engines that we have today. They are based off of 1970-1980's technology and are not meant to build power to 10,000+ rpm.

As far as your build, I would go with 11:1 on either the stock bore if the cylinder is good or go to a 416 so you could run pump gas. Either way will be a drastic difference in power. As for the 450r carb, do it. It will pull much harder throughout the entire rev range and is honestly one of the best mods you can do for the money. I think the only mod that has better performance for the money would be a timing key on a stock EX.

I have no experience with larger valves in the EX and I do not know anyone who has done anything besides a port and polish. I would imagine that there could be some power gained with larger valves but only with a "race engine". The RFVC head on the EX actually flows surprisingly well or so I have been told and is even better with a port and polish.

As for cam choice, think of the XR cam as a hotcams stage 0.75 and then the hotcam stage 1. Both are very similar but the stage 1 hotcam will be a little more aggressive with more mid to top end power and the XR cam more of an exaggerated stock power band.

[jsl1213]

probably a dumb ?, but do you have to make any adjustment to run without the air box lid?

[jsl1213]

probably a dumb ?, but do you have to make any adjustment to run without the air box lid?

[99RED4X4]

Considering that the motor runs well now, stock, with the exception of some faint black smoke when I nail it (rings or valve seals I think - already fixed the rich issue) I might be able to get by staying stock bore. That would save a pretty penny.

So those $250 rev boxes are junk. I figured they weren't that great considering noone ever talks about them. I knew not having a rev limiter was bad news, but thought maybe the increased spark made a difference.

I've definitely heard alot about the sparks timing key though! Must be a worthwhile mod if 80% of people on here have it and suggest it!

450r carb huh? That sounds interesting. Time to start searching Ebay!!



jsl1213 - I doubt you'll hurt anything running it like that, but technically you should re-jet if you pull the lid off.

[99RED4X4]

http://cgi.ebay.com/ebaymotors/Honda-450R-450-Carb-Carburetor-Stock-Intake-_W0QQcmdZViewItemQQhashZitem483bdf706bQQitemZ31024 2144363QQptZMotorsQ5fATVQ5fPartsQ5fAccessories


Is this what your refering to? They're really that cheap????

What are the wires hanging off the bottom for?

Correct me if I'm wrong, but basically by doing the carb swap, its just a conversion to an FCR carb which is just about the most common carb seen on the high performance machines of today? (lots of little mods available for them too)

[99RED4X4]

I forgot, this is DILLWAD, my 2000 400ex.

(not the best picture, but he's at his homeland, Yellow Creek, Ohio)

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs640.snc4/60080_430235711212_650586212_5662650_254183_n.jpg

Pretty much stock, used to have yellow plastic.

I don't have my works shocks on here, the lower bearing/bushings went out on them before this trip.

Also, I gotta get rid of these 22in. tall rear tires. They came with it, and man they're nice for getting through mud, and i rarely bottom out, but they roll like a SOB!

20's are too small, I'm thinking 21's

*Look closely at my front storage box. Its exactly the same as the ones that you guys are talking about on the "400ex Storage" thread, except I put mine on the front so I don't flip over hahaha

[99RED4X4]

And this is what we like to ride -


http://sphotos.ak.fbcdn.net/hphotos-ak-ash2/hs347.ash2/62783_430237771212_650586212_5662700_2912023_n.jpg

[99RED4X4]

When I was 13, I rode this -

http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs661.snc4/60119_430738946212_650586212_5674117_3561603_n.jpg

[matt1106]

yes usually you will have to rejet


Originally posted by jsl1213
probably a dumb ?, but do you have to make any adjustment to run without the air box lid?

[matt1106]

yes usually you will have to rejet


Originally posted by jsl1213
probably a dumb ?, but do you have to make any adjustment to run without the air box lid?

[ish416]

If your EX is running fine at the moment you could just hone the cylinder and throw in an 11:1 piston. I would get it checked and make sure that everything is still within tolerances.

The only advantage that some of the rev boxes offer is advancing the timing by +3 or something similar. Still, they are a waste of money as most 400EX rev boxes are just XR250R cdi's with a bit of tweaking done to them and usually cause cold starting issues.

As far as a timing key. They are the best bang for the buck of any mod you can do to a stock EX. The stock compression ratio is something like 9:1 and a +6 timing key will really wake it up. However, if you run a +6 key on an 11:1 engine you may be asking for trouble without running higher octane fuel (race gas mixed with premium or E85).

As far as the 450R carb, I am running a 41mm Sudco FCR carb and it is a pain to get jetted properly. They are the absolute best carbs you can get but are extremely finicky with temperature and altitude changes. Most people that I know are running the 42mm 04-05 450R carbs. They seem to be much less finicky with the temp and altitude changes. Also, you most likely will not be losing much if any power compared to an FCR.

As for your ebay link, I am not sure what you are referring to as it tells me the item has been removed.