440?

[Jnblaster05]

so im thinkin im gonna get my 400 bored to a 440 any one who has got this done how much of a diffrence did it make im thinkin curtis x 6 pipe and stage 2 hot cam im gonna race hare scrambles this year like will i be able to keep up with 450 and i was thinkin 14 tooth sprocket any info or suggestions would be great this si gonna be my first time doin this racing thing

[CSR400EX]

i liked my 440 a lot, but if you are gonna be running hare scrambles, i would look into suspension and/or chassis upgrades before any motor work.

[400thacker]

I agree with CSR

however...you can make more power with a stock bore than a 440cc big bore under certain circumstances. compression is what matters in bore and piston selection.
You can't safely bore your engine to a 440 without resleeving your engine. if you want to bore it at all go with a 406 bore or 86mm just to freshen it up and get a 10.8:1 or 11.0:1 compression piston. you will not have to resleeve it and you will notice a SIGNIFICANT difference in power. Also, if you ever need to freshen it up again you will have room to bore it out again. 440 is a big of a bore that you can have on a 400ex unless you stroke it as well. after 440 it's new cylinder jug and sleeve time. stage 2 hot cam would be good with a after market rev box but a stage one will do everything you need more than likely.

what i was saying earlier is that a stock motor with just a 11:1 comp piston will out perform a 440 big bore with a stock compression ration.

14t front aprocket would be good and i stongly suggest curtis exhaust from everything that i read however i like HMF or YOSHIMURA exhaust. you could go to a 406cc with 11:1 compression of for about $150 if you shop smart and do the work yourself.
I got a full gasket kit for 25 and shipping off ebay piston and rings will run less than $100 and then whatever it cost to hone your cylinder which wouldn't be much V.S buying a new sleeve for the 440, piston and rings, having the old sleeve removed and new one installed for no less than $50 then having that honed to make sure you have teh right tollerances, gasket kit, not to mention over heating issues
that way you could still have money to build up your suspension with some elka products or whatever you prefer.
just my 2 cents.

[CSR400EX]

the Sparks X-6 is the best exhaust for a 400 IMO. i agree with 400thacker, you can get the same power as a 440 out of a 406, 416, with 11:1 compression, stage 2 cam, exhaust. the rev box is a good idea as well, just find one that isnt a XR250 CDI, or you might have starting issues. but in tight trails, suspension is gonna help you more than power would.

[Jnblaster05]

so maybe a 416 with a 11 to 1 piston would that still run pump gas i have wheel spacers now ive been wanting to get a nice suspensino but i want a arms and shocks which is around 1600thanks for the help here guys i appreciate it

[REPOMAN]

i have that setup. stage 2 with the x-6 exhaust, 440 kit with 11:1 wiseco piston, ported head, k&n and alum. air box. i assure you this setup has absolutely no problem from the 450 section. power gains from stock are enormous.

[Soutehrn_Style]

Put it this way, I raced a 06 LTR 450 with a slip on a chip with 18s and stock sprockets with my 440, stage two hotcams, K&N, stage 2 dynojets, and hmf pipe with stock sprockets and 22s. We raced from stop and three times. At most he was 1/2 bike length ahead and once we got to 5th I started to pass him and have about 6-8 mph over him wide open. Also raced a 426ex and it wasn't much of a race... I think a 44 kit is what all 400exs need, that and suspension. I know they only say 6-8 hp gain but you REALLY feel it. Only problem is 12.5:1 comp blows head gaskets but when mine blew i put a new one and gasket sealer and have never had a problem. Next mod for me is rev limiter. DO IT!!! WISECO! OHH and also, after ridding a pred with fox podiums for a year, the stock suspension F**cking sucks!!!!!!!!!

[400ex28]

I wouldnt jump right to the 440 first, go 416 or 426.

[400thacker]

don't go over 11:1 compression and you can still run pump gas. ;)

[nofear911]

I think you would be ok with 416 on the stock sleeve, I cracked a sleeve on my 426 then put the thicker on in on my 440.

I liked my 426, but really got the bottom end when I changed to 440.

As for cams, I went with the stage one to improve the bottom end for xc style racing and hill climbing. My buddy had stage two and they acted completely different. I could kill him in the woods, he could kill me on the mx track.
Just something more for you to think about.

By the way, I haven't had a 450 get around me yet. All fairly stock though, just pipes.

[Soutehrn_Style]

12.5:1 is the highest on pump (93 octane). All your major street bikes gsxr, yzfR, zxr, cbrs, run around 12.5:1 and as high as 13.3:1 (Kawasaki). If you run anything less it will combust before it sparks and cause a loud ticking noise and is hell on your engine. Most people that blow their timing ran 87 with their big bore so don't EVER run anything less than 93. And as far as going to 426 first. That's spending money twice for the same thing. It's not unmanageable power. I went straight to the 440 and have ridden a 426 and all I can say is go big or don't waste your time. I'm running a wiseco and definatly recomend. Get a real good spark plug too.

[TRXRacer1]

Originally posted by Soutehrn_Style
12.5:1 is the highest on pump (93 octane). All your major street bikes gsxr, yzfR, zxr, cbrs, run around 12.5:1 and as high as 13.3:1 (Kawasaki). You just named a bunch of liquid cooled street bikes. Compression doesn't require higher octain, the extra heat it creates does. The liquid cooling on those bikes allow them to handle the heat of the higher comp pistons much better then an air cooled engine. Apples and Oranges. Hell I can make my 10:1 ping if I run 87. You're asking for trouble running anything higher then 11:1 in an air cooled engine on pump gas.

[Soutehrn_Style]

"compression doesn't require higher octain" Hope your not serious. What makes an octain is it's stability, the lower the number the more unstable. There are two things that ignite fuel, spark and compression so if it ignites from compression before the cylinder is at top dead center you will hear a tick and it may jump timing because the ignition is trying to push the cylinder backwards. Heat actually lowers your compression ratio (why there are such things as intercoolers). Altitude also lowers your compression ratio that's why the higher the elevation the lower the octain and a vehicle that requires 93 can run on 87 at a higher elevation. I've tun 12.5:1 in my 440 for a little less than a year on 93, I've been to dunes, regular trail ridding, and even some track days and have never had it ping. compression.

[TRXRacer1]

Originally posted by Soutehrn_Style
"compression doesn't require higher octain" Hope your not serious. What makes an octain is it's stability, the lower the number the more unstable. There are two things that ignite fuel, spark and compression so if it ignites from compression before the cylinder is at top dead center you will hear a tick and it may jump timing because the ignition is trying to push the cylinder backwards. Heat actually lowers your compression ratio (why there are such things as intercoolers). Altitude also lowers your compression ratio that's why the higher the elevation the lower the octain and a vehicle that requires 93 can run on 87 at a higher elevation. I've tun 12.5:1 in my 440 for a little less than a year on 93, I've been to dunes, regular trail ridding, and even some track days and have never had it ping. compression. I am very serious. I'm glad you have a rare 440 12.5:1 that doesn't need race fuel but to suggest this for the rest of us this is nothing but bad advice. Not one 400ex is igniting fuel on compression alone. Comparing a 400ex to a liquid cooled street bikes is like holding up a sign saying you totally don't get it. The only reason any 400ex is going to need higher octane fuel is heat and higher compression is a direct contributer to higher cylinder temps. That's why liquid cooled machines can run higher comp pistons on the same octane fuel, they keep the cylinder temps lower. That's why sometimes my 10:1 starts pinging, because I'm riding it really hard and it's getting too hot. That's also why when you run an advance key with a mild piston you can get pinging, because it's firing closer to TDC and running too hot. As long as you have a way to keep the cylinder temps down, like the liquid cooling in those street bikes you mentioned, you won't have a problem.

[Soutehrn_Style]

"Not one 400ex is igniting fuel on compression alone." who said that? I said when fuel is ignited by compression before the cylinder reaches TDC is what causes pinging. You really think that you can have any compression you want and run on 87 as long as you can keep it cool? :confused: So what do you think octane rating is? The temperature it burns at?? :rolleyes: Who told you this???

[CSR400EX]

lol. call wiseco and they will tell you anything higher than a 11:1 in a 400EX, you should run 100 octane or higher. you wonder why you blow head gaskets with a 12.5:1 and pump gas (detonation):rolleyes:

just today my dad told me the gas he put in my bike was 93, but when i smelled it, i could tell it wasnt, it was probably 87:eek2: you shoulda heard that thing ping when i got on it hard.

[Jnblaster05]

so im thinkin wiseco 11to1 piston and a 440 kit i think ill get some good power out of that

[TRXRacer1]

Originally posted by Soutehrn_Style
"Not one 400ex is igniting fuel on compression alone." who said that? I said when fuel is ignited by compression before the cylinder reaches TDC is what causes pinging. You really think that you can have any compression you want and run on 87 as long as you can keep it cool? :confused: So what do you think octane rating is? The temperature it burns at?? :rolleyes: Who told you this??? LOL, who said that........ you should know you quoted me.

I'm not saying pressure has nothing to do with it but you're still confusing the root problem here when you say "fuel ignited by compression". The level of pressure that these machines create is not enough to ignite the fuel. I don't care if you're running 13:1 it's still the added heat that is causing the problem. You run a 13:1 in a 400ex and you'll detonate your engine to pieces on pump gas but if you did that same 13:1 in an engine that could cool it and that same pump gas would be fine. You could without a doubt make a 13:1 liquid cooled engine run on 93 octane if you properly cooled it. Octane is a measurement of resistance to pre-ignition and even in optimum conditions you do need to raise the octane level. I never said you could run anything you want on 87 and I never would but you'd be surprised how much pressure that 87 could handle if you could keep the combustion chamber cool.


Originally posted by Jnblaster05
so im thinkin wiseco 11to1 piston and a 440 kit i think ill get some good power out of that Absolutely! Pair it with the right cam you'll have a killer machine.

[Jnblaster05]

if i go 440 do i need a bigger carb?

[CSR400EX]

a bigger carb would go great with all the mods you are wanting. a 450R carb would be a wise investment.

[Jnblaster05]

so i dropped it at the shop this afternoon im gettin the 440 kit with 11 to 1 compression and a hot cam stage2 i bought a x 6 exhaust this mornin im so pumped guy says hell have it done in like a week

[curlyatju]

Hey blaster 05 how much did the 440 kit and installation cost you without exhaust or cam. im curious cause im thinking of doing the same. pm if you want. thanks

[Jnblaster05]

um with out that it would be like 750