Engine Top-end Rebuild

Looking to get some more torque out of the 450 engine. Looked at an engine builder site that claimed big results with putting a 10.5:1 piston, webcam,kibble valve springs, more air and open up exchuast on the 450 and it would out run a stock 660 engine? I'm not real savy on engine building, but would like to do some upgrading to my 450. Any good ideas from any of you builders. I'm not interested in buying a new bike with bigger displacement.

Kenny how much would it cost , maybe check out a 660 swap then you could mod it even more later    an remember there is no replacement for  wait for it.... displacement    

I've thought about the idea of saddling up a 660. What I've seen you are eye balling $2.5K - $3K + for a used 660 motor, and there isn't chit around here for used Rhino parts. I like the 450's low-end but she could use more torque with all the good I've got her packing. Lighten the load and she'd do just fine to run up and down dirt roads but that's not my ridin style. Maybe I think I can get to much out of the 450 engine. I'm like a dog with a bone, don't want to giver up.

how big of a cylinder /piston can you go to  get that 450 up to 500 maybe , what about the grizzly 550 top end would it fit/work on your 450

The biggest I've found at JE was (10.5:1) 86.5 = 440 cc, the stock is 84.5 = 421 cc. I think if the memory is correct.

if you work with a builder ask to see dyno sheets first and then talk about how much money it will take to get there.

keep in mind that runnability (heat output, smooth idle, noise, power band) will be affected as well as reliability.

make sure you know exactly what you want before you start the build

Denny you always have good input, but I'd not even know what a Dyno sheet looked like, power to the wheels? Don't have any real atv/utv builders here other than dealership shops and I wouldn't take anything there to get screwed with.

Kenny G wrote:

The biggest I've found at JE was (10.5:1) 86.5 = 440 cc, the stock is 84.5 = 421 cc. I think if the memory is correct.

what about Wiseco?  its 11;1. stock is 10;1

Thanks Joel