what is the best overbore for a 400

[chad400]

02 400ex is starting to burn a little oil (excuses excuses lol) wanted to get 440 kit but people say to go with 426 or 416 help!! any pros or cons....... also hear 12.5-1 is to hard on starter

[04hmf400]

I would go with the 416 because it will leave you with one more bore on you stock sleeve. Also you should go ahead and put in a cam.

[chad400]

will i be able to notice a gain with a 416 and cam

[04hmf400]

A 416 with just a cam will pull away from a stock 400 easy.

[TRXRacer1]

I'm about to do the same thing. I'm going with the 426. Here's the deal, I still want to do the 440 some day but I want to see the difference everyone is talking about first hand. The Wiseco sleeve($70) for the 440 kit is made so you can start out at a 426 if you want to. What's nice about that is your not running your stock sleeve thin and you still have another bore left(440). I called my local shop and if I bring them the cylinder they install the sleeve and piston for 1.5hr of labor($100). I'm going with the 11:1 piston because I'm looking for power and I don't want to max everything out and I don't want to do a crank job as it is recomended for the 12:1 pistons. The only thing I'm undecided on is the cam. I think I will go with a hotcam but I don't know if I want the stage 1 or 2. I like the specs on the stage 1 but if the 2 is tons better I don't want to cheat myself. Good Luck.

[chad400]

thanx for the replies

[400Ex_Rida]

I would go with the minimum bore and a cam, .020 over. Unless you really want to go with a 416. .040 over is a good bore as well.

just my opinion

[hoser 400ex]

416 is .080 over...... im still undecided to which size i'm goin to. either 416 or 426... maybe even a stroker....

[ghak99]

Originally posted by hoser 400ex
416 is .080 over...... im still undecided to which size i'm goin to. either 416 or 426... maybe even a stroker....

Maybe?, just do it!;) Go with the fresh 426 sleeve and the 4mm stroker. This should give you a 440cc motor. And the ability to bore to the 440 bore at a later date to give you 460cc

[Kennethyfz450]

Just think the bigger bore you got the bigger the piston and it will slow the revs down a bit.. so its not really what kind of bore is the best its what else you are going to do with it..

i would recomend you get a cam and a fcr 39 carb and a high compresioin piston where you need to run mix gas.. dont cheat yourself..

also if you go a little more money go ahead and buy a stroker you will not regret it. but remember dont go over you head cause something so fun can turn into a lot of trouble if you know what i mean ..

[TRXRacer1]

Originally posted by Kennethyfz450
Just think the bigger bore you got the bigger the piston and it will slow the revs down a bit.. so its not really what kind of bore is the best its what else you are going to do with it..

i would recomend you get a cam and a fcr 39 carb and a high compresioin piston where you need to run mix gas.. dont cheat yourself..

also if you go a little more money go ahead and buy a stroker you will not regret it. but remember dont go over you head cause something so fun can turn into a lot of trouble if you know what i mean ..
Sorry man but you've got it backwards. It's the longer stroke that makes it rev slower not so much the bigger bore. Look at almost all of your high rev machines, they have shorter strokes. The 400ex is a 85mm bore with a 70mm stroke. The quicker and higher reving 450r is a 94mm bore with a 64.8 stroke. Your YZF is even more of an example. It has a 95mm bore with a 62mm stroke.

[sharkinthepool]

Originally posted by chad400
02 400ex is starting to burn a little oil (excuses excuses lol) wanted to get 440 kit but people say to go with 426 or 416 help!! any pros or cons....... also hear 12.5-1 is to hard on starter

As for the starter????
I have run a stroked motor with some custom 463 13.75:1 custom J/E piston in it for 2 years and never had a problem!

[Kennethyfz450]

I typed that backwards thanks for correcting me


but the bigger piston does slow the revs down but not as much as stokin.. either way you are going to gain some power.. so do it right and go smoke some yfz's and R's

[Carl Nevins]

go as little as possible, after stock you loose alot of dependability. Just learned alot about that this year the hard way. it's not fun watching your buddys race from the side of the track

[TRXRacer1]

Originally posted by Carl Nevins
go as little as possible, after stock you loose alot of dependability. Just learned alot about that this year the hard way. it's not fun watching your buddys race from the side of the track

http://www.bluetraxx.com/phpBB/images/smiles/bs.gifEven the 440 kit is reliable when done right. Don't give people bad advice because you got screwed.

[sharkinthepool]

Originally posted by TRXRacer1
http://www.bluetraxx.com/phpBB/images/smiles/bs.gifEven the 440 kit is reliable when done right. Don't give people bad advice because you got screwed.


This is so TRUE!

Do not be afraid to wait an extra week to have the money to do all the little things. My 440 was one of the most dependable motors I ever raced or rode. I went two years before I started even seeing any burn and almost 3 before the head gasket needed replaced. That was my fault for not waiting and using a heavy duty head bolt.

[Steve-o 400EX]

Definately go with the 416, its the best bang for the buck, i highly recommend it with a stage 2 hotcam, pm me with Q's.

[Abrab916Ex]

I understand the best cam for the 400ex is the hotcam....but wats the difference between the 1 and 2.......if i have a 400 with t-4 slip on, K&N air filter and jet......wich would be best with my quad...some 1 please explain..

[TRXRacer1]

Stage one is a strong mid range(RPM) cam with a shorter duration and stage two is a strong top end cam with a longer duration.
1 = mid
2 = top

[Steve-o 400EX]

Originally posted by Abrab916Ex
I understand the best cam for the 400ex is the hotcam....but wats the difference between the 1 and 2.......if i have a 400 with t-4 slip on, K&N air filter and jet......wich would be best with my quad...some 1 please explain..

I would recommend the stage 2 if you ride hard, if you are an average trail rider i would recommend the stage 1. Either one will work great with a slip on and an air filter which is what i have.

[TRXRacer1]

Originally posted by Steve-o 400EX
I would recommend the stage 2 if you ride hard, if you are an average trail rider i would recommend the stage 1. Either one will work great with a slip on and an air filter which is what i have.

Common mistake, it's more about your riding style and where you want your power. It's not about how hard you ride.

[fmf400ex03]

about this 416. I dont really want the 426 becuase its the last bore plus if the 416 aint enough i can go bigger. with a 416 i need gaskets valve seals piston kit stge 2 cam and bore is that all? Also when people say they beet the stock with this set up what do u consider buy beeting it like theres no chance you just keep pullin away or is like slightly. Also can i run a stck pipe with it for now till i get the money or is that not recamended?

[markk]

Originally posted by hoser 400ex
416 is .080 over...... im still undecided to which size i'm goin to. either 416 or 426... maybe even a stroker....


I would go with the 416, My motor had done great for me.
The power gain is tremendious for the amout of $ u put into your motor, It revs quick (to hang with the 450 in 1st and 2nd) and it likes the RPMS. The only disadvantage to the 426, is i hear that they make a little bit of heat!!!!

Im gona to take my motor back down again this winter, and Buy a new pistion and rings, and Try to get my crank streched out another 4mm's, And with my 416 .080, 87mm pistion and my 4mm stroke that should put me about a 440stroker.

Actully check out GT thunder they have some nice 400ex motor mods, The 450stroker is sweet!!! Brandon Summers rode one and Dominated his GNCC Class!!!!!!!

[fmf400ex03]

the lakes are freezin and winter is commin so i have alot of drag racing ahead of me mainly racing pipes 400ex and z's. with that set up what should i expect for the most part we all have studs so we hook up good

[fmf400ex03]

can i run a stock pipe on a 416

[47501exracer]

I am getting my 400 punched to a 416 this winter with a stage 1 hotcam. My question is why is it called a 416? When I looked at both Ross and JE's websites they state the displacement as a 415. I am guessing with all parts, boring and gaskets it will cost about $350 bucks. Does that sound right? I plan on putting it back together myself to save money although I'd rater pay someone. I have a complete manual.

[47501exracer]

Originally posted by fmf400ex03
can i run a stock pipe on a 416

IMO, I would get a good pipe first and then rebuild later when you have more $. It won't hurt to run it that way, but the pipe will make a big difference to go along with the overbore.


Hey, I finally have 100 posts.

[fmf400ex03]

the rents are getting me an exhaust cuz my dad smashed my old1 but can i run a stocker

[Steve-o 400EX]

yes you can run a stock pipe on a 416, i dot his and am very happy with it. I would use an exhaust that is more opened up, like an e series with no discs.

I believe the actual size of the displacement is 415.5, so the round it to 416., i am not 100% on this but i believe that is why.

[markk]

Originally posted by fmf400ex03
can i run a stock pipe on a 416


YEah, BUT with an aftermarket pipe u will notice a HUGE diffrence!!!!, I have one of my stock pipes, that i Choped up, and i made a shorty out of it, with nothing inside, ITs really loud, but it doesnt sound that great! Its 1/2 the lenght of what it used to be. U could chop that pipe up, and keep some of the packing in there, But i have to say its alot easier just buying a pipe from somone, or somwhere!


Yeah i just figgerd that they rounded up on the displacement on the 415's, and the 425's!!! I dont know y!!!!!

[fmf400ex03]

thanx for the info cuz i am getting an exhaust but i want to get the stuff for a 416 wile i have the money cuz i know i ll blopw it on some thing else when i buy only and exhaust so i will never get a 416.

[400-416EX]

you wont be dissapointed with the 416 purchase. I love mine, if you can afford it look into getting it ported. Once you get it all done let us all know what you think of it Have fun building

[440ex#28]

I have ran a 440 for about a year. It has been dependable and the power gain was great. the power is even better with aftermarket large carb.

[chad502ex]

416 for hp
502 for torque! :D

chad502ex.com