have heard that 416 better than 440. how?

[medicdude]

not understanding how it can make more power, by only increasing 16cc. vs 40 (or 35 actual from what ive seen).

also, ive read that no machine work is required for the 416 kit. that would obviously be much nicer for my wallet.

thanks for the advice.

[Rancher2005]

I had only heard that a 416 was better in the reliability department although some may argue that. It would keep your cylinder temp down as they still have a larger wall thickness. And it may also rev quicker if I can assume it is lighter than the stock or 440 piston.

[GPracer2500]

Originally posted by medicdude
not understanding how it can make more power, by only increasing 16cc. vs 40 (or 35 actual from what ive seen).

also, ive read that no machine work is required for the 416 kit. that would obviously be much nicer for my wallet.

thanks for the advice.

When I re-did my old 400EX I chose an 87mm piston (416cc) mostly because:

1) I wasn't comfortable going to an 89mm piston without upgrading the cooling (bigger oil tank, maybe scoops, and maybe an auxilary oil cooler). When it comes to ATVs, I dune almost exclusively and heat is a concern.

2) Although an 87mm piston does require machine work (boring of the stock sleeve) it avoids having to have a new sleeve installed. I've personally seen more than one big bore sleeve fail (by dropping in the cylinder). The aftermath is ugly. Mostly that's an installation issue--and I do have a competent machinest--but sticking with the stock sleeve cuts down on one way the build can screw itself.

3) Smaller bores are fundamentally less prone to detonation. Admitadly, 2mm isn't anything to write home about in that regard--but still. My build pumped ~175 psi cold at 1300ft (that was a 10.8:1 JE with thin gaskets and a HC stg 2) and I still HAD to use a 50/50 mix with my settup/riding. I wanted to stay with pump gas but it didn't happen. Granted, AZ pump fuel is crap so YMMV.

4) I didn't want the expense of purchasing a full exhaust system. Not that it's a requirement with an 89mm piston, but I'd expect the stock headers to start becoming an unwelcomed restriction as you reach or exceed 435cc.

5) I didn't want the expense of head work beyond the replacement of worn stock valvetrain parts. Same sort of logic as the head pipe--building a good motor is as much about matching complimentry components as anything else.


I just decided that a basic 416 build was a better choice for the 400ex, FOR ME. I felt like it was either go all out and build a full-on 400ex or keep things basic and save my money for a new ATV in the future. The 400ex is what it is, and IMO that doesn't include being a hotrod dune machine.

I think an 89mm piston does have more potential for producing big HP numbers than a smaller piston. But the end result is more about the package than one particular part.


BTW, piston weight doesn't necessarily corelate to bore size. A 10.8 87mm JE weighs 26 grams more than a 12.0 89mm JE.

$0.02

[mach1stang]

not to highjack this thread but i have a few questions on the two stroker kits too,
1. would you need to run race gas in them?
2. do the kits cut the reliability down any?
3. whats the cheapest place to get a new kit?
4. is there alot a other mods i should do to back them up?

[Wheelie]

A 416 is a bore kit, not a stroker.

1.depends on the compression ratio you decide to run.

2. If you buy quality parts, and build/have it built right--IMO--no.

3. What are you looking for?

4. Depends on what you decide to go with.

[mach1stang]

sorry i am used to car motors and we call them strokers alot.
basicly i am wanting a motor that i can build that will run good and is still reliable cuz i am building my every day basher and i figured why not do a engine while i am building it

[underpowered]

Originally posted by mach1stang
sorry i am used to car motors and we call them strokers alot.
basicly i am wanting a motor that i can build that will run good and is still reliable cuz i am building my every day basher and i figured why not do a engine while i am building it

well they do make stroker kits for the 400ex, but it is more common to bore. on cars, you get more of a gain out of a stroker than a bore. like a SBC 350 can be bore out to a 355,360 etc but it is more common to see it stroked with a SBC 400 crank to a 383.

but for your questions

1. fuel depends on CR. stay below 11:1 and you should be fine on pump, any higher than that and atleast a mix with race fuel is recomended.

2. reliabilty really depends on how the motor is build. i went 3 years on my 426 without any problems so yes it should be reliable.

3. depends on what all you are gonna get. i like to stay local, so try your local shop first. then check C&D on here, they seem to have good prices.

4. i would get a piston, cam, HD studs, HD cam chain, good exhaust (if you don't have one already) . then you could also have the head P&P and get a good carb as well.

[mach1stang]

ok this is my first build and i am doing it from the ground up so i am trying to get as much info as possible but i plan to buy somthing that needs to be rebuilt or somthing so i can throw a cam and stuff in it.