What C.R. with pump gas? [Archive]

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FIREHAWK116

04-12-2007, 07:07 AM

I am thinking about replacing the piston in my 05 450R. What compression ratio should I go with and still be able to run preimium pump gas? Also what is the stock C.R?

400exrider707

04-12-2007, 07:25 AM

EDIT: stock is 10.5:1, you can use 12:1 safely.

GPracer2500

04-12-2007, 09:17 AM

Stock is 10.5:1 for 04/05. :blah:

400exrider707

04-12-2007, 09:24 AM

Originally posted by GPracer2500
Stock is 10.5:1 for 04/05. :blah:

ooops mistype!

ratso

04-12-2007, 10:48 AM

I think you should put 14.1 piston and mix race gas with pump. race gas is about $4 to $6 a gallon. The gas in CA is pretty bad even the supreme,they want $3.60 a gallon for it.

The power increase from 10.1 to 14.1 should be about 4% the cost of pistons out here in CA is the same. This would also be a good time to change the cam and maybe do porting.

Sorry this is a little off topic but I wouldn't run pump gas in anything that is going to be ridden to the extreme. I have torn down many motors and the damage pump gas does to valve seats is horrifing.