Author Topic: Should i go to a High Compression piston??  (Read 1356 times)


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Should i go to a High Compression piston??
« on: July 11, 2010, 08:18:00 PM »
i am having my cylinder re-sleeved back to 80mm, having it ported and polished, and a new piston and rings. is there an option for a higher compression piston still at the stock 80mm and is it a good idea to use it? i want to keep the machine reliable and i always run 93 octane fuel with honda racing synthetic two stroke oil 32:1


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Re: Should i go to a High Compression piston??
« Reply #1 on: July 12, 2010, 05:44:07 AM »
First, sleeving is a bad idea. The replacement sleeves do not replace all the original leaving a band of cast iron. So you end up with a sleeve in a sleeve. This causes poor heat transfer. With the additional heat output from the porting, the cylinder will run hot. It is about transferring heat from the piston through the sleeve to the cylinder itself so a water cooled head will not address this issue.

You do not use a different piston to raise compression. A ported cylinder (at least my porting, may vary with others), running just the bottom layer of the stock head gasket and a head with a combustion chamber size equivalent to a stock head shaved .008" will result in compression just at what you can run on fresh 93 octane.