400 to 440 help

[DominicD400ex]

Well I purchased a wiseco 440 kit that includes the new cylinder and the piston is 12.5:1 compression.

I understand that I should install hd head studs and probably a new cam to get the best out of it.

As far as installation and other parts to help reliability, what should I do?

I realize now that I should have gone with 11:1 but that's too late.

I'm NOT trying to make this a race quad.
I simply want to give my 400ex a little more go and want to know what is necessary to install this kit.

I will be doing strictly trail and recreational riding.

any help is appreciated.

[416exman21]

you have to get crank and rod ,prob. some hd clutchs, def. a cam,get your head work done hd rockers and hd valves-hd springs,you need an elctric fan for cooling,hd studs, and i would get your cyclinder coated with nicsol (i think that how you spell it lol it will help on lasting longer and cooling and all around cyclinder life ..it cost but well worth it .

[scdirtdobber]

Hmm,I've been looking at some Big bore kits without having to beef up the bottom end,which may or may not have to be done,maybe this will come up in this thread

[DominicD400ex]

I updated my initial post to include that this is not a race bike and i just need the essentials to install the kit and keep it reliable.

Thanks to those who have replied so far.

[rob_990]

you shouldnt need a new crank/rod unless the one you have is bad.get a cfr 450 timing chain.hot cam stage2.with hotcams you use your stock rockers.id throw in some kibblewhite valves/springs if you have enough money.and some stiffer clutch springs.i wouldnt replace your entire clutch unless it starts slipping.your also gonna need gtt heavy duty studs studs.

[rob_990]

get a 4"spaul puller fan to help keep it cool too

[rideracelivemx7]

valves and all that other bs above, dont worry about it, 12:1 your risking snapping your rod , thats why i wen twith 11:1, yeah you shoulda done head studs, just buy morehead gaskets if your going to be a hard rider. your clutch will hold up, if your turboing it, then youd need a clutch, these engines just dont have the oomhp to spin a clutch, and stock clutch is actually favored in some applications and is very reputable.

[RIDEREDson]

a fan only keeps it cool when your riding trails. If you're on a track then its pretty much useless.

[aDviSol2y]

If your just trail riding, you should have gone with the 416. You don't have to worry about doing any of the crap these guys are talking about with the 440. There are well documented test that show the 416 is just about as good as the 440 as far as power wise. And reliablity wise the 416 is far better. You run a 440 side by side with the 416 and you will be neck and neck. Where you will see the differance is climbing a steep *** hill climb. I have raced 440's and smoked em on many occasions. The lighter piston makes it much snappier and quicker.

[EXinMB]

i had the same thing at first i ran the 440 kit you bought with a hot cam stg 2 and a dp clutch kit with stock carb a k&n and stock exhaust and it hauled. then i added a slip on pipe and fine tuned the jetting and i smoked the brand new clutch kit and one head gasket. i changed both and smoked the clutch again. now im running 3 steel honda plates 3 dp steel 1 fiber dp and the rest barnett fiber (big screw up royal distributing listed the wrong amount of fiber plates) and dp springs and this clutch grabs and now i have the hd studs in and i hope that works.
so my opinion is if you have the money and still have it apart do it all right the first time and just build it as if it was a race motor. same thing as using a 450 for just trail riding. but just do it all right cuz if you build it on a tight budget it'll cost more in the end just like mine but i can still pull holeshots on piped 450s :-)

[DominicD400ex]

see, now after hearing some of your responses i'm thinking that a 416 or 426 may be a better choice for my application.

I realize that if i put this kit on, my bike can seriously haul ***, but i'd rather have the reliability and not have to worry about things like clutches and head gaskets.

I'd rather just get a 416.

[aDviSol2y]

Good choice.

[powertechn2]

well, i had 2 people NOT buy my quad because they thought it had too much power, they were looking for something stock, and then planned on piping and jetting it, they are now going to buy a stock one, then pipe and jet it and install a K&N and spend more than they coulda bought mine for in the end... just because they what, cant not go full bore? its nice to have the power when you need it, but not always use it.

first off, why were you building it in the first place? does it actually need rebuilding? or are u just looking for a lil more power?

i have seen a lot of 440 kits running with stock lowers, and no problems. most weren't that high of compression, but if you already have the kit, you can just get a lower comp piston.

as far as reliability, as long as you do a stud kit, even if you only do a 416, its worth doing, you shouldnt have gasket issues, and as long as its assembled correctly, it should still be reliable and offer good longevity.

if you were just looking for a lil more power, do you have an exhaust?

if you dont have an exhaust, you should really look in that area before rebuilding if its not necessary. get a good full system, get a pro flow kit or a K&N filter, and an ignition kit, and you would be surprised at the feel difference from stock.

if i did my engine again i would go with a lower compression piston personally. it sucks trying to get race gas in b.f.e.



as far as reliability, im in a toss and turn situation right now, my quad is built, makes plenty of power, just really like a few of the new quads out, have listed mine on craigslst, and been looking at new even went to buy one, but got bait and switched lol. if i had the room, i would just keep my quad now, but dont have enough storage area. however, looking at alot of the newer quads, if i bought one, im loosing some of the bulletproof-ness that the 400ex's are known for.


as far as clutches go, i have had to go through 3, first one the springs came loose probably on the dyno, cause first ride i felt it slipping hardcore at 9k rpm powershifts, so i took the oem clutch, and the dp kit that was installed, and reinstalled the thickest of everything, and then the new perforated steels, that held for a lil bit, till i dragged it at the hill a few too many times... then i finally got a dirt racer ebc clutch kit, and its held pretty well so far... it does slip if i powershift consecutively, or drag a ton, but at the time the extra plate kits were outta stock.

if i didnt ride it hard, a stock clutch would actually hold up well, esp if you judt did stiffer springs.

[DominicD400ex]

Thanks for your input man.
The kit I bought ended up being bought back by the seller, so i'm back to square one.

I'm considering a 416 with 11:1

hd studs will still remain on my list of things to add.

I do have an exhaust, although it's a slip on.
I have modded my airbox and got a new filter, and my bike is jetted for my pipe.

My engine has been ridden hard since i bought it in 04 so although the rebuild is not absolutely necessary, I would like to go through with it.

[powertechn2]

well, you could even just do a cam in your engine, and go to full exhaust.

if your not looking for super power gains, anything you do will suffice, but you can always do the cam now, and the exhaust, or buy a header pipe that matched your slip-on, some are able to do that, and then save the rebuild for later.
or do the 416 kit, then save the cam and header for later.

no matter what you do, just dont get crazy compression if you do trails.


i originally wanted just a lil more power, then by the time i was going to do a 426 kit, i just figured it would be a lil more $$ to go to the 440, but then figured its apart, might as well stroke it... then might as well port it and do larger valves, then needed larger cam... then might as well swap carbs... then might as well cryo all sortsa stuff... and i can say i went overkill for my application, but im happy other than the race gas.

[aDviSol2y]

Originally posted by powertechn2
well, you could even just do a cam in your engine, and go to full exhaust.

if your not looking for super power gains, anything you do will suffice, but you can always do the cam now, and the exhaust, or buy a header pipe that matched your slip-on, some are able to do that, and then save the rebuild for later.
or do the 416 kit, then save the cam and header for later.

no matter what you do, just dont get crazy compression if you do trails.


i originally wanted just a lil more power, then by the time i was going to do a 426 kit, i just figured it would be a lil more $$ to go to the 440, but then figured its apart, might as well stroke it... then might as well port it and do larger valves, then needed larger cam... then might as well swap carbs... then might as well cryo all sortsa stuff... and i can say i went overkill for my application, but im happy other than the race gas.

What kind of HP are you getting from your bike? Have you ever had it dyno'd?

[powertechn2]

yea, its been on the dyno.

47 at the rear wheels, and a lil over 33lb/ft. it has a really good wide torque curve and spread out powerband, you can lug it around a gear too high, and it still hauls.

i would post an image of one of my runs, but all i can find in my puter are my runs from before i got the carb tuned in, even then it was 45hp and 32lb/ft, but just not as impressive as that extra 2 hp lol.

i can do one more cam swap, and should hit 50, was going to do it this spring, but havent been out riding, and been busy between selling my bike i had, and now trying to decide if i want an outlaw 525s, or a ktm 525xc...

have still been thinking about doint the cam swap, but then ill have yet another cam with ten hours on it sitting around, and im only asking 2700 for my quad, would even settle on 2500, so i dont really wanna drop the money just for sits and grins