need experience to answer this one

[rmcfadden68]

my 05 400 ex seems less off a bike over the last 3 yrs. i need new excitement. im wondering 416 426 or 400 big bore kit. i dont want a ton of maintence to come with it. and i dont wanna hav 2 worry about head caskets. should i stroke it?

[JBENSON]

Originally posted by rmcfadden68
my 05 400 ex seems less off a bike over the last 3 yrs. i need new excitement. im wondering 416 426 or 400 big bore kit. i dont want a ton of maintence to come with it. and i dont wanna hav 2 worry about head caskets. should i stroke it?


I have rode a 416 & 426 with stock cam & stock porting, I think they run very well for just a bigger bore & hi compresion piston.
As far as maintence & head gaskets you will be fine. Most people only have problems with head gaskets if they over tighten the head bolts because it will pull the studs out of the cylinder. Use stock torque specs. Hope this helps you.

[rmcfadden68]

thats what i was looking for im probaly gonna go 426. so i have one more step if need b. thnx

[matt14c]

I would go 416! Overtightening the studs isnt the only reason they pull out. The higher compression does this also. It is highly recommended to get the gt thunder studs with anything over a 416. Even with a 416 its not a bad idea. With a 416 you wont have any additional maintance that you would with stock. Depending what you have done to your bike now there are some things you could do to really wake up a stock bore. Sparks key, programmable cdi, better coil, higher compression stock bore or a 406, 450r carb.

[derekhonda]

416, 426, leave the stock studs. 440, call gt thunder you need them. Thats been my experience anyways.

[derekhonda]

and for the record I was in the same boat about 3 years ago, slight bore to a 406, 11:1 piston, trail cam (cant remember, not super aggressive though, new K&N (just replace the old K&N) and a full exhaust, $500 bucks later it felt like a brand new machine.