is a 400ex stock bore with 11:1 compression possible??

[sideways]

I was down at the local quad shop today and looking into higher compression pistons for the my 400. I was looking to get around 11:1 compression with hotcams stage 1 and wiseco piston kit (85mm). Now the person at the quad shop said i cant go to an 11:1 piton without getting a 86mm cylinder, which would then require boring and whatnot. I am basically trying to stay with stock cylinder size for now but i want more power of higher compression. I am not interested at all in a 440 kit, if any it would be a 416 and a year or so down the road.

is it true that i cant get 11:1 compression without going to a bigger size piston?

[TORO1968]

I believe that with most of the stock-bore, high compression pistons, you'll net around a 10.5:1 compression ratio.

You may be able to get more out of it by running thinner gaskets...anyone wanna chime in on this?

BTW, if you're wanting a high compression piston, screw the Wiseco and get in on the Ross piston group buy from C&D Racing! :)

-Jordan

[frogburner]

I got the next size up,, Mine is a 406 with 11:1 High-comp.,, And your stock Rod will be fine for that compression,, if you exceed over that, your depending on a little ole OEM rod in there to hold your motor together... just something to think about..

[sideways]

lets say im staying with the stock bore size (85mm) would the 10.5:1 compression with the stage one cam give me a lot of power increase? what does higher compression do in terms of making power?? does it make the engine rev out faster or just increase engine output at the same revs? the 400 is going into the shop on wed, so i would like to get everything that i want squared away before then. right now the only question is to stay with stock piston and re-ring, or go with the ROSS (instead of wiseco) piston with higher compression.

[WKY400EX]

I had an 11:1 stock bore piston, XR400 cam, filter, and X-6 full system on my 400EX. Over stock, it's a huge difference in power. It just didn't run with the 440's. I originally didn't want to go big bore with the EX, so I went with the stock size piston. If you're tearing into your motor, might as well port and flow the head too. Just my opinion.

[tinner]

Wky is right. If you have the $$ get the head done too. Check into the different piston mfg's. I have a 10.5 JE stock bore. Night and day difference over stock. Along with all the other stuff...GTT cam, Porting, HMF full pipe.

[BiggerRed 400ex]

will a higher compression affect longevity of the motor?
Thanks,