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Discussion Starter #1 (Edited)
Going to be tearing down my 650 to do the cam chains and was thinking about getting the heads machined for a little bit more compression. I always use 91 marine fuel and though maybe I could bump the compression up a bit. Has anyone did this to a stock machine? I it worth it and will it still be reliable? I did a search and couldn't find anything. I also couldn't find any 650 base gaskets that were thinner.
 

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ahhhh if i were you ... i'd install forged pistons do w.e compression you'd like 11:1 12:1 ... all the base gaskets are the same for 650 and 800's you can find base gaskets any size you want from places like Mrrpm,the bom racing, get torqued they can get you w.e size you need... so if u wanna go with a 11:1 piston and go to 11:5 compression you can change the base gasket right same thing with the 12:1 piston ... if you shave the heads you could run into piston slap issues which can be fixed with a thicker base gasket but i think i'd put the forged pistons in it if you have it apart its a power adder abit and its alot easier then having your heads machined check out this calculator for setting up compression ratios Engine Compression Ratio (CR) Calculator
 

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Discussion Starter #3
So say a .015" base gasket would bump the compression up a tad would that cause piston slap? I don't want to replace the pistons I am sure they are in great shape. I want to keep it on the low budget side. Might just leave it stock.
 
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