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MPAQALLIS

ac 310, K241

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Dadsy98
These Kohlers have Automatic Compression Release (ACR). My service manual says it is difficult to obtain an accurate compression reading. You will need to crank the engine over 600 RPM to overcome the ACR. When you get a service manual see section 9 for info . Otherwise, I'm sure a member here has a general idea of what the compression range should be. Steve

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HubbardRA
From what I recollect, these engines only run about 6 or 6.5 to 1 compression for the flatheads. The newer OHV engines may have more. With the limited cooling of these air cooled engines, they must keep the compression low to prevent overheating. This is why they run so well on low octane fuels.

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HubbardRA
John, I milled .060 off a 10Hp head then installed it on a K321. Used it for pulling, but wouldn't even think of this set-up on a work tractor. Don't think the engine would last long.

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acjohn
I only took .030 off because I wanted to be able to bump the HP and still run mid grade pump gas. The engine needed a .060 over piston, so I figure I'm making about 12HP. I have a spare head in case I have long term problems. I know that air cooled engines are much more sensative than water cooled, but I don't think I've pushed the limit too far.

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