what would you recomend 440 or 426

[wv400ex]

I am getting ready to redo my 2000 400ex in a few months and I was just woundering for those who have bored ther quads out how they liked them and what you would recomend to bore one out to? I have heard some bad stuff about the 440 but I have not heard anything on the 426. So Please let me hear your alls opinions. Thanks.

[JRDrider22]

440 all the way.its what i got and it keeps up with 450's.very nice along with nice power

[redroost85]

I would go more conservative first time around. If you do up the 426 right, you will be able to hang with many of the larger quads. I have seen this first hand at the local tracks too.

There are some guys on the board here that have some pretty stout 426's....hit them up a pm and I'm sure they would love to tell ya about them.:p

[wv400ex]

If I would go with the 440 Is there any work that needs done to the head? Should I have it board or just resleve it? I haven't done much internal engine work.

[wv400ex]

On the 426's do they run cooler then the 440's? The riding that I do is well 50/50, 50% easy riding with younger riders taking it slow and staying in the back toi make sure they all have a safe ride and the other is well usaully with my bud's I have grown up with and every time we ride it is a race.. So what do you all think would be the best for me?

[EXtremeEXer50]

i would do a 426 the 440 has an awful lot of compression and if not dont right u will be blowing head gaskets like crazy!

[member]

Originally posted by EXtremeEXer50
i would do a 426 the 440 has an awful lot of compression and if not dont right u will be blowing head gaskets like crazy!


i didnt know that displacment had to do with compression... :o

[EXtremeEXer50]

I was just giving him my opinion the 440 is hard on an engine!

[squeak12]

i would reccommend boring to 416 and strokin to 440 if thats what you want

my friend has a 440 & it is alot faster then the stock 400ex but it cant touch my 450r.... I would go 426 & keep your reliability

[wv400ex]

It sounds like the 426 is more for me. So I think I will end up going with that. Thanks for all of your input on this.
Does anybody recomend any certian company to go through to buy the stuff that I need?
Thanks again

[440ex2001]

A 440 kit will not be any harder on your engine than a 426. Compression ratio is not determined by the piston diameter. It is possible to have a 12.5:1 piston and a 440 11:1 in this case the 426 would be more apt to have head gasket probs. Remember this rule THERE IS NO REPLACEMENT FOR DISPLACEMENT. If you go to a 440 kit you dont have to bore or re-sleeve your head. You cant do that its impossible. You will have to bore and sleeve your cylinder though.Go with the 440 it has more potential

[440ex2001]

Originally posted by 440ex2001
A 440 kit will not be any harder on your engine than a 426. Compression ratio is not determined by the piston diameter. It is possible to have a 12.5:1 piston and a 440 11:1 in this case the 426 would be more apt to have head gasket probs. Remember this rule THERE IS NO REPLACEMENT FOR DISPLACEMENT. If you go to a 440 kit you dont have to bore or re-sleeve your head. You cant do that its impossible. You will have to bore and sleeve your cylinder though.Go with the 440 it has more potential

I meant that a 426 could have a 12.5:1 and a 440 could have 11.1:1. Ther426 would be harder on the engine. Just keep the compression below 11.5:1 to keep to reliabe.

[wv400ex]

Ok thanks for all the input

[TC426EX]

426 all the way man. It can be bored on the stock sleeve and revs faster than a 440 and runs a little cooler. My 426 has no problem keeping up with the 450's in races. Im not denying that the 450's are a little faster, but it all comes down to rider skills. I just have to work a little harder for that position and make less mistakes, but it's still competitive. For the type of riding you do just go with the 426 and forget about it. What else are you planning on doing to it? Just simply boring it will do little for your power. You need to at least go higher on the compression with the piston kit and add a drop in cam at the BARE minimum. Ideally you want to look at some head porting too, it makes a difference, and then you'll be around where you want to be and youll have a whole new bike. As far as who to get it done by, any of the top engine builders will do a great job like TC, Sparks, GT Thunder, Baldwin Motorsports, etc. From what I hear, GT Thunder does some excellent work and have a fast turnaround time and good prices. Dont forget to add a full exhaust if you already havent too...If you need any more info let me know...

[cals400ex]

Originally posted by TC426EX
426 all the way man. It can be bored on the stock sleeve and revs faster than a 440 and runs a little cooler. My 426 has no problem keeping up with the 450's in races. Im not denying that the 450's are a little faster, but it all comes down to rider skills. I just have to work a little harder for that position and make less mistakes, but it's still competitive. For the type of riding you do just go with the 426 and forget about it. What else are you planning on doing to it? Just simply boring it will do little for your power. You need to at least go higher on the compression with the piston kit and add a drop in cam at the BARE minimum. Ideally you want to look at some head porting too, it makes a difference, and then you'll be around where you want to be and youll have a whole new bike. As far as who to get it done by, any of the top engine builders will do a great job like TC, Sparks, GT Thunder, Baldwin Motorsports, etc. From what I hear, GT Thunder does some excellent work and have a fast turnaround time and good prices. Dont forget to add a full exhaust if you already havent too...If you need any more info let me know...


i don't know if you do much drag racing, but what is the outcome of a drag between your and a 450r or yfz?? given equivalent rider skills and weight. also, mention where you have an edge or where they have the edge in the race. thanks

[TC426EX]

OH I cant beat a built 450R or YFZ in a drag race but its close. I dragged a YFZ not too long ago with a full Yosh system, cam, and high comp. piston (full 450 not 439 or whatever) and out of 10 runs I lost ten times by about a bike length or 2. He did have his bike geared for more top end so I did get a jump on him at the start off but once it hit 3rd he had me every time. When I race I usually try to get an inside line and then pinch off in front of as many riders as possible at the first turn. The YFZ's and 450R's (with an equal rider) will pull a little off the start on me but I have had some top 3 starts this year. As far as stock ones, I have beaten alot of them but it may have been the riders, not sure. Throughout the race the 450's will have an advantage in the straights and I have to out maneuver them in the corners and whoops just like anyone else. I still race against just as many if not more EX's as 450's.

[wv400ex]

I think I will go with the 426. What brand would you recomend for the cam and piston kits? I don't want the best out there but I don't want any junk either. So let me know what your thoughts are on that.

[TC426EX]

Piston kit go JE or wiseco. From what you said I think you should go with a hotcam stage 2, and if you want to spring the extra change then get the TC MX or XC cam.

[cletusEX]

Originally posted by cals400ex
i don't know if you do much drag racing, but what is the outcome of a drag between your and a 450r or yfz?? given equivalent rider skills and weight. also, mention where you have an edge or where they have the edge in the race. thanks

My buddy has a 440 that will pull a 450R out of the hole and run away from them. Both the 450r's that he ran against have changed the front sprockets for the woods, so they sacrificed a little top end.

[cals400ex]

Originally posted by cletusEX
My buddy has a 440 that will pull a 450R out of the hole and run away from them. Both the 450r's that he ran against have changed the front sprockets for the woods, so they sacrificed a little top end.

what is done to his bike?

[cletusEX]

Originally posted by cals400ex
what is done to his bike?

JE piston bought from LRD(I think they do a special coating on it), i think 13:1 compression, web cam 479 grind, shortend vavle guides, bigger valves, ported head, full hmf system, stock gearing, running on 110 race gas. it's got a lot of *****

[cals400ex]

Originally posted by cletusEX
JE piston bought from LRD(I think they do a special coating on it), i think 13:1 compression, web cam 479 grind, shortend vavle guides, bigger valves, ported head, full hmf system, stock gearing, running on 110 race gas. it's got a lot of *****



does he pull thru all gears or just the first few? also, with the bigger valves, how much bigger than stock?? bigger on the intake vavles only or both intake and exhaust?? thanks

[cletusEX]

Originally posted by cals400ex
does he pull thru all gears or just the first few? also, with the bigger valves, how much bigger than stock?? bigger on the intake vavles only or both intake and exhaust?? thanks

He was pulling them out of the hole and all the way up to 4th. The guys on the 450r's are my brother and other riding buddy. Just so you don't think I'm talking about dragging some random guys. I'm pretty sure he went 1 mm bigger on all the valves.

[balls2da-wall]

Originally posted by wv400ex
If I would go with the 440 Is there any work that needs done to the head? Should I have it board or just resleve it? I haven't done much internal engine work.

Buy Wiescos 440 kit for 250$ and you should be set! It comes with a new sleeve just have a shop do that for you it ran me about 100dollars and they even resurfaced my cylinder. You really dont need any work done to your head but it would make it faster if you had it ported. On my 440ex I have the air box lid removed, K&N fliter, and a LRD pipe with a jet kit and that thing runs like a champ...I feel if you go with a 426 you will just be wanting more power when your done so maybe you should just go all out for the 440!

P.S. make sure you put locktite on the cam gear bolts unlike me!!!:D It's not pretty when the cam gear comes off and you bend all of your valves:p

[markk]

Originally posted by squeak12
i would reccommend boring to 416 and strokin to 440 if thats what you want


Thats the 440 u should go with.


Actully, if your looking for HP's cheap u should go with a 416kit, I have heard that the 426's rev up quick, and make good tourge, The 440's that i have ridden rev slowley, and they dont feel like they have the snap im looking for, but they do make tourge!! For the long hill climbs.

If i where to do it, i would build the 426 with everything i could to keep the quad cool! But if you have the money u should stroke the crank, and bore to a 416, Thats a real 440!, And then when your top end goes, U can still push it out to say a 465!