400ex cam question.

[mittman]

Ok well its time to throw some money at the quad since I havent in a LONG time. My buddy told me to do a 440 and convinced me to buy and new cylinder so I bought a 89mm one and he also said about a stage 2 hot cam. I was getting ready to order it when I thought to myself maybe I should ask this to a few 400 guys first. I do trail riding no racing at all I open it up a few times during the day while riding but its not in reving high all day long. Our trails consist of rocks so a lot of my riding happens in 3rd but sometimes requires 1st and 2nd to get over the really rocky areas. Now my question, stage 1 or 2 hotcam for my style of riding? Any info is very much appreciated!

[tri5ron]

You start off by saying you want to "Throw some money at your quad",...
But,
what is more important here,...
...is that you don't end up Throwing your money, AWAY.

Your buddy is doing you no favors by suggesting a 440 is a good choice for a TRAIL machine.
Here's Why...

This is purely my own opinion,..
and I have no doubt, that others are going to chime in, saying you are going to be fine with a 440, with either a stage 1 or 2 cam.
(and is probably biased, with what they run, wish for, or drool over).

I'm going to assume that you are asking your question, to get Actual, Experienced, and Educated, Advise,...

to result in a Reliable, Dependable, Solid, trail machine,...
based on the information you have stated.

Your style of riding, and terrain, sounds very similar to mine.

As a trail rider,
your priority concern is not necessarily which cam you should buy,
but rather, how you are going to keep your air cooled engine from over heating, while riding at slower speeds, in demanding terrain, and limited airflow across the oil cooler, and engine.

You don't say what compression ratio your 440 piston is, so I'm going to assume it is at least an 11:1, (or higher).
Therein lies the main problem for a trail ridden machine, that in all probability, is going to see some significant useage, rpms, and producing some significant heat.

The quick and simple answer, for a cam choice, on a 440 at 11:1 , 12:1, etc.,.... is a stage 2.

BUT,....

That is not the best choice as a TRAIL Ridden machine.

Again, it's all about managing, and eliminating the HEAT.

A 440 , (in my opinion),... and knowledge,... of the characteristic traits, of a TRX400EX, is a poor choice.
This is due to the thinner cylinder walls of the 440.

Combine that with a 11:1, (or greater), C/R, and the heat issue becomes even more critical.

Again,... in my opinion,...
Yes, a 11:1 c/r, CAN be used as a TRAIL ridden machine, ... but is not really advisable due to the potential for having a detonation issue on pump gas, at your higher temps, and lower air flow.
A 10.5:1, on a 416 bore, would be about as high as I would go, and personally I'd STILL be looking at the heat issues.

A spal fan, and/or, a larger oil cooler mod, would be the first choices in the war on heat.

You also do not mention, having, or getting, the GTT studs installed.

These are HIGHLY advisable for maintaining reliability in any build, that includes a higher compression piston,... and is going to see some significant heat.

So again, in only MY opinion,...
a 416, 10.5:1, stage 1 , is a solid top choice for a TRAIL Ridden machine.

Anything beyond that, starts setting you up for exponentially increasing issues, and points of intrest that need to be considered.

With the above combo, you could safely and reliably add a 450r carb, and a +3 or +6 timing key, and even a mild P&P job.

Don't even THINK about changing the CDI from stock.
The OEM box, is HANDS DOWN, the BEST box for ANY 400EX,...
Shy of a big bore, high compression, stroker motor, properly built for drags or dunes. (we're talking big $$$ here), and not even CLOSE to what you are asking.

Trails get dusty, so a foam oil filter is advisable, and a good slip-on of your choice, and cleaned up head pipe welds, will complete the package.

My advise would be to sell the 440 kit to your buddy that talked you into buying it, and getting a 416 at 10.5:1, and a stage 1 cam.

You'll have a seriously improved running machine, (about 35 hp), that is reliable, runs on 91/93 octane fuel, and will always bring you back to camp from a long tough ride.


hope this helps.

[chronicsmoke]

^I agree Ron..

416 (11:1)
Cam (IMO Stage 2)
P&P
Slip-On (Search the classifieds)
Uni filter (30$ brand new)
450r Carb (search the classifieds)

^ thats a pretty peppy 400ex ;)

You might need a cam chain/HD studs if you want to do it right..

I wish there were more definative results using the rev boxes.. I still here about as much praise as I do bashing on them..

I guess there's only one way to find out, but I can live w/o it..

But to be honest, If I had a 440 jug in front of me, I would probably run it anyway unless I could find a buyer for it.. Sure you might have problems over heating ect, but you may not. You'll have to add more things to get it reliable (Spal fan, larger oil cooler, HD studs, full exhaust) but you will get more power in the long haul.. If you're not dead set on a 440, I'd consider your other options too :)

Are you doing the work yourself, or haveing a mechanic look at it?

[mittman]

I wanted to do the 426. I figured it was a all around bump up from stock and would suit my needs. My buddy said well if your going in there might as well do it right with a 440 kit. I couldnt find a kit with a 12:1 so I just ordered the cylinder and was going to get the piston from JE and the cam from hotcams. As for the cylinder im sure I could tell the guy I dont want it but I did already pay for it. So Im kinda in between what I should do. I dont know maybe ill just stick with it and just get a bigger oil cooler or a fan. Oh and my buddy is doing the work since he works on atvs pretty much every day.

[chronicsmoke]

Originally posted by mittman
Oh and my buddy is doing the work since he works on atvs pretty much every day.

Always nice to know somebody that knows what they are doing..

At the end of the day, nobody on here can make you do anything.. If you're set on a 12:1 440cc bike, (you being the owner of the 440 cylinder). Just go ahead and do it.. but dont just throw it together or you'll be out more $$$ when it blows.

you will "need"
HD Headstuds (especially with a 440 @12:1 CR - see GTT)
Spal PULLER fan (Ebay ~35 bucks)
I'd get a bigger oil cooler too, but that's just me.. You're going to generate alot of heat with a 12:1 piston.


^^
Do you need those things to run? No.
Do you need those things to run and be reliable? IMO, YES!

[mittman]

Will I be able to run the fan without needing any upgrades to the electrical system? I would read up on it but I'm on my phone won't be home till tomorrow

[chronicsmoke]

Originally posted by mittman
Will I be able to run the fan without needing any upgrades to the electrical system? I would read up on it but I'm on my phone won't be home till tomorrow

Yes, the Spal fans draw very little..

Somebody had the exact number in another thread.. I'd suggest reading up on it when you get a chance.. Theres numerous ways to mount it/tie it in to the electrical system.

[mittman]

Ok thanks. I decided its easier to just do a 440 since I already have the cylinder ill just finish ordering parts tomorrow. Ill just spend a lil more to keep the heat down. Oh and is it worth it to pick up a tto temp meter? Thanks tri5ron for info also!

[chronicsmoke]

NP, there is a good bunch of guys that frequent the 400ex section. Always somebody willing to help.

I suggest going slow when you're building, make sure you have the right tools, and post pics up as you go.

If you dont have a manual, and your buddy doesnt have a manual.. GET THE MANUAL! it'll save you headaches later, and I think someone has it on here for free DL

:bandit:

[Thumpin440ex]

The 440 will work fine, but def like said do the GT thunder head studs.. A over sized oil tank is a must imo, the fan is a good idea. I have not done a fan.. There are some threads floating around with fan installs.. Also do a crf timing chain. take your time.. I have ran the piss out of my bike, in hot weather this year, it hasn't missed a beat.. Of course mine is done right, not rushed.. Alot of good info in the thread for sure.. My specs are in my sig. you will be more then happy when your done.. :D

John

[dxcody]

my only advice to you is dont be dumb like i was, (i still am just not quite as dumb as i was before these forums)
ask anyone on here, i bought a 400ex (it was a hunk of junk)

I should have started from step 1, my wheeler didnt run when i bought it, i tore it all apart, bought a hotcam and ranit from there.

these guys told me, while i had it apart, to go ahead and replace the timing chain because it stretches them out having them off then on then off then on, i didnt.

I decided to throw it together and ride it, now i have ruined my valves, scared my piston, now i have to get a complete rebuild kit. and have it rebuilt.