416 Vs 426

[Cannonball08]

Is there a big power difference between the two?

[SlapNutz]

NO

:macho

[UglyMotha™]

Originally posted by SlapNutz
NO

:macho

you okay there slappy:huh

A buddy of mine has a TC racing 416 national kit on his 400ex....sucked in some dirt and had to have pushed to a 426..

I noticed no difference between the 2 at all. Now just doing the bore alone you could probably see a difference but I'd just go with the 416 just for the fact you can bore it again if accidents happen....:eek2:

[Pappy]

426 super gorilla:macho

[Dune Surfer]

I went from a 416 to a 426 and I can definatly feel a differance. It feels stronger on the bottom to mid range.

[Steve-o 400EX]

Originally posted by Rico
A buddy of mine has a TC racing 416 national kit on his 400ex....sucked in some dirt and had to have pushed to a 426..

I noticed no difference between the 2 at all. Now just doing the bore alone you could probably see a difference but I'd just go with the 416 just for the fact you can bore it again if accidents happen....:eek2:

I agree, There is only a very small increase with a 426 and you might need to bore it again if something does ever happen.
I garuantee you will be plenty happy with a 416.:macho

[Cannonball08]

Thanks guys I will just go with a 416 to be safe.

[Dune Surfer]

chicken:rolleyes:

[Cannonball08]

I don't need a 426 or a 416 to go fast. Its 5% bike 95% rider.

[Steve-o 400EX]

Originally posted by Cannonball08
I don't need a 426 or a 416 to go fast. Its 5% bike 95% rider.

true that, i am gettin a 416 this spring.

[jcv400ex]

Yeah, you'll only feel it off of the bottom. I'd get my buddy off the line, but from there on out, it was neck and neck. I'd do the 426, Gobs and Gobs of low end power, and heck a sleeve is only $65....

[86atc250r]

Well, here it goes again...

At .080" over (416) the sleeve is getting pretty thin.

Yes, pistons are available that will allow you to bore to .120" over (426cc).

At one point I had measurements on how much sleeve this left, but have since forgotten - but it's not good.

Can any one of us feel a difference of about 9cc's on our engines (all else being the same) - I REALLY, really (and I mean really) doubt it.

That said, having seen them bored, and after talking to several engine builders - you've really got to question how much potential reliability is worth to you.

Do you want to push the envelope on a stock sleeve for performance that you'd be VERY hard pressed to feel or see?

Will all 426's have problems? NO. Are there folks who will come on here and say "I've had my 426 for xx years and never had a problem", YES... Are there engine builders that will refuse to bore your stock cylinder to .120 over? YES.

Now you have the info - do what you're comfortable with.

Me - I'm sleeving and going 435 (440) for my next rebuild instead of boring my 416 again...

[forum]

the main reason why engine builders bore the engine out to 416 in the first place is to clean up the cylinder fram any scrathces or wear. THere not trying to get extra hp boost from just 16 cc's cause thats rediculous. 16 cc's isn't gonna do a damn thing. For those of you who say well my 416 is way faster then my stock machine. well then you must have gotten other mods with that 416 then just the actual bore. Im going to run a 11-1 piston in my stock bore back up ex. and have the head flowed and get a cam. Mainly because i want a relaible machine for a back up. and the larger you bore the thinnner the head gasket and My buddy had so many problems with head gaskets blowing all the time i don't wann go throug it again. Otherwise i'd go 440. Is a white brothers track cam any good?? I don't want to trade my stock cam in when i buy a new one so don't tell me about them kind.

[jcv400ex]

With the stock bore, a XR 400 cam would do you good.

Yeah, Gabe hates the 88mm pistons....there's been alot of discusion in here and in yahoo about the reliability of a 88mm pistion in a stock sleeve. Personally, I had great luck with mine, and it's still together. Hetrick 425 is now the proud owner.

And it's .118 over....:p


A port and polish on a stock bore is not going to do much for you, your better off spending the money else where.

[Razorback]

I've just recently upgraded to a 416 (JE piston), but I didn't just have the piston done. I changed to a Sparks X-6 full pipe, Sparks race cam (I believe it's the one in his 416 national kit), hardened rockers, new valve springs and guides, and port and polish.

I'm supposedly up around 38 hp now, and plan on adding an FCR 39mm carb soon, and that'll get me a couple extra hp and a steep jump in the in-the-seat-of-the-pants feel :)

The difference is amazing to me. I actually feel like I can keep up a lot better in the races now. Not having the horsepower is no long an excuse for me :D