Automatic Compression Release

Mon Nov 22, 2010 7:32 pm

Has anyone eliminated the ACR in a Kohler K series engine. Just curious. I'm cleaning a 10 HP engine from a 105 in preparation to rebuild it and was just wondering if the ACR can be eliminated without great consequence.

Re: Automatic Compression Release

Mon Nov 22, 2010 7:57 pm

I have a 100 that had a 2 piece cam from the factory. It did not have a compression release. The starter could hardly spin the motor. I replace the 2 piece cam with a newer 1 piece cam and haven't had any problems since.

Your 105 and my 100 have the same starter-generator system. My 100 has a new wire harness and the starter generator was rebuilt.

Why do you want to eliminate the ACR? There won't be any noticable power increase.

Re: Automatic Compression Release

Mon Nov 22, 2010 9:03 pm

I have no reason to remove the ACR other than fewer moving parts. My feeble mind was just wondering, and I think you verified what I was thninking that the starter generator would barely turn the engine without ACR.

Re: Automatic Compression Release

Tue Nov 23, 2010 3:16 pm

The ACR is there for the purpose of getting the engine to spin fast enough to start. The 7 HP with the 2 piece cam have a spark advance that don't let the spark fire till it reaches TDC which throws the piston down in a hurry so if you have enough battery to get it to TDC they fire on the second turn and usually don't even have to choke them. The points in a 7 HP must be set correctly and it's very hard to use a timing light on the 7 HP. I have a 7 HP TEST engine that I set the points and then take the push rod and the points and put them in my other 7 HP. I only did it one time but my 128 wouldn't start and that engine had been running hot ever since I got it. I took the points out of the Test engine and the 128 started up and didn't run hot using it to cut my grass this year.

If I set the points on my test engine the come out about .020(the setting don't change taking them out) and the cam and push rod aren't worn that engine should be set very close to .020. I want to try that on some other tractors to see how close the timing comes to the S with a timing light.

The ACR's don't have much problems except for having a spring come off or the PO started to bend the ACR which was adjustable on the early models, They changed the ACR tab to one that would break on later models f you tried to bend it. It's a good system and don't cause many problems. The slow turning can be caused ba a lot of other things.