what kind of hp gains from 416-440 kits?

[04EX]

Like the title says i was just wondering what type of gains i will be looking at if i bore my 400ex. mabey someone has a dyno sheet.

[H_W]

Boring alone is not going to give you much more power. But add a cam and some port work and you will see a nice gain.

[CHEVYZ]

Cam and full exhaust should be your next mods of choice, not bore. Big bores can be a PITA if you don't build them right, not to mention they will not produce the power increases you see from other mods that you have yet to do.

[GPracer2500]

Bumping up the compression (regardless of bore size--you can stick with stock bore if you can/want) and swapping the cam along with basic intake and exhaust mods will make a big difference.

The stock 9.1:1 static compression ratio and stock cam specs are quite mild.

just $0.02

[H_W]

Originally posted by GPracer2500
Bumping up the compression (regardless of bore size--you can stick with stock bore if you can/want) and swapping the cam along with basic intake and exhaust mods will make a big difference.

The stock 9.1:1 static compression ratio and stock cam specs are quite mild.

just $0.02

I couldn't agree more.

[04EX]

I would probally do the 440kit with the bill ballance full exhaust, hotcams stage 2, edelbrock carb, k&n filter with outerwares, highperformance clutch, and im sure there is more that i am missing. Oh and of course bump the compression but im not sure if i want to run pump gas or race gas.

[400eXr1d3rZ]

You can bump the compression to 11:1 and you could still run pump fuel (93 octane).

[04EX]

91 is the highest that is sold in Az at the pump so i would probally have to run race fuel anyway.

[GPracer2500]

Fuel in AZ is junk. My 10.5:1 406cc JE would knock ever so slightly at the dunes. My 10.8:1 416cc JE would knock everywhere on our crappy 91 unless you took it real easy. The 416cc pumped 180 psi cold at 1300ft, btw.

[jmccary]

I was planning to do a 440 kit, head porting, a cam, and ss oversize valves this winter but I am still unsure about the compression ration to go with. Anyone have an opinion on this one? I live where we only get 91 octane and I don't really mind running race gas since most of my time is on the track (others at the dunes). How much performance am I going to gain with a 12.5:1 over an 11:1? Is it that significant to make the higher compression worth it? I was told that reliability shouldn't be a big problem as long as the decking and gaskets are done correctly.

[04TRX400EX]

So in a little while I am planning on getting into my engine to get some more power. I have a buddy with a JE 416 kit with a Hot Cam and a FCR carb that hauls a*s. Since I rode his quad, I have always said that I am going to build the same thing, but I have heard along the way about doing a high-comp piston instead of the bore ...

What differences will I notice between doing the following -
* JE 10.8:1 piston bored 2mm over (which I think is a 416cc, right?)
* Hot Cams Stage 1 or 2
* FCR carb (which is the 450R one, right?)
-vs.-
* high-comp standard bore JE piston
* Hot Cams Stage 1 or 2
* FCR carb

[H_W]

I don't know what the difference between the two, but I know the standard bore JE piston, hotcam stage 2, and FCR carb work extremely well together. My 400 is pretty quick, just not quite as quick as my yfz 450. It was closer than most people would think when the yfz was stock..