stage 2 cam question

[grassman]

i wanted to do a 426 kit.. i was going to get a 11:1 compression piston so i can still use pump gas and keep the heat down for trail riding.. should i use a stage 2 cam with this set up or has anyone done this and what kind of results did you get.. thanks

[hypersnyper6947]

I would go with stage 2 with that set up, go for it

[rideracelivemx7]

12:1 and up is recommended for race gas, i had 11:1 440 and stg2 cam and iwas all dandy, i used 93, no heat difference from 93 and 87 at all. id recomend just using 93 thought, its alot more air and compression in there than the stock 9:1:eek2:

[BigLuke]

I run 12.1 and a stage 2 cam with 110 race gas, I could deff tell a tempeture difference on the race gas. I was told that with a stage 2 cam I would loose a little bottome end power but it seemed stronger.

[F-16Guy]

If you bump the compression ratio up, it's going to offset any loss created by the cam (which is exactly why people combine a high compression piston with a higher lift/duration cam). If you go to 11:1, I think you'll find that the bottom end is still going to feel really strong, and the mid and top end is going to rip!! My personal advice, unless you're already there, is to go to a 406 or 416. If you go directly to a 426, you're out of overbores, and the sleeve is on the thin side. There have been more than a couple 426s that cracked a sleeve. You're not going to feel a huge power difference from 10-20cc. Most of the new HP will be from the cam and higher compression ratio piston. I would also advise doing head studs. They're a weak area on the 400ex, and nothing sucks worse that going out riding with 10 hours on a fresh rebuild and blowing a head gasket. Mine blew on the starting line at a WORCS race. Not fun. Stage 1 or 2 HotCam or any other cam is your preference, but if you go too radical, the rev limiter is going to kick in before the cam signs off. Good luck with the build.

[grassman]

i thought about going with a 406 or 416 bore just to be able to use the sleeve for another bore but honestly the sleeves aren't too expensive from what ive seen, so i figured go all out. but i was wondering about the walls being too thin. my main thing is that i ride trails with alot of technical riding. alot of uphill and tight turns and occasional full out fast as it will go road rides...(no more than a couple of miles). each ride i take is about a 3/4 tank of gas worth... so i really want to keep heat down and with thin walls im worried it wont last me as long as i need it to. what would be better....416,426,stage 1, stage 2??? it all seems good to me. i really just want more reliable power.. ( but who doesnt).... thanks for the opions

[F-16Guy]

Yeah, you can put a new sleeve in, but it will get exponentially more expensive when you have to split the case, flush out all of the metal chunks, and fix any damage they caused. I would say go with the 406. I built a 406 for my buddy with an 11:1 Wiseco piston, Cometic XR400 gasket set (with the laminated steel head gasket, not fiber), and a Hotcams stage 2 cam. It ripped really good with just premium pump fuel and had no heat issues. The studs are optional, but I wouldn't build a high compression 400ex engine without them. My advice would be to buy the parts from the cheapest place you can find them (probably online somewhere), and then send the cylinder along with the new piston to GT Thunder to have it bored and have the studs installed. You will need to have the new piston with the cylinder when you send it in so they can get the clearances perfect. Most good shops would never even try to bore a cylinder without the new piston for reference. If you do that, your engine will be just as bullet-proof as a stocker, if not more so.

As far as stage 1 vs. stage 2? I love my stage 1 cam. It pulls like a tractor, and might be good for the type of riding you want to do. The stage 2 pulls good, too, but with more duration, the power band moves higher in the rpm range. It really depends on your riding style (revver vs. lugger) and terrain. The stage 1 is probably going to lend itself better to woods riding. The thing to remember is that you will see power gains everywhere vs. stock, it's just a matter of where you want the "meat" of that power.

edit -- I think I used an OEM XR400R gasket set on the 406. With a 1mm overbore, the stock XR gasket set will work perfectly, and Honda quality is the best. Use the XR set because the head (and base, I think) gaskets are thinner, which will get you closer to the advertised compression ratio of the piston. I think most piston compression ratio numbers are based on using XR gaskets on the EX.