ac 310, K241

[MPAQALLIS]

What should the compression be for the motor??

[RonT]

Welcome to the club. I'm not exactly sure of the compression specs for this motor but a rule of thumb is 100-125psi. I have seen motors run with 50-80psi but not real well.

[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

[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.

[acjohn]

I have a K241 with only about 15 hours since complete rebuild. I milled .030 off the head so my compression should be higher. I'll run a compression test and let you know tomorrow. John

[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.

[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.