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912 ac mower compression

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Category: Allis Chalmers
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Topic: 912 ac mower compression

Posted By: nickia
Subject: 912 ac mower compression
Date Posted: 20 Jun 2010 at 11:43pm

does any know what a 12hp kholer motor has for a compression rating? Thanks

Replies:

Posted By: Brian Jasper co. Ia
Date Posted: 21 Jun 2010 at 6:30am

It's hard to say right off. They have a mechanical compression release that disengages once it starts. Are you having problems with it?

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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford

Posted By: nickia
Date Posted: 21 Jun 2010 at 5:24pm

im lacking power she is a oil burner and wanted to do a compression test to see how bad she is i thought i may want to check the valves for carbon build up getting a lot of backfiring if my valves are not seating may be the reason for lack of power i know when i changed the spark plug the electrode had a lot of build up on it

Posted By: Dusty MI
Date Posted: 21 Jun 2010 at 6:17pm

I have a very old Simplicity with a Kholer, 14 hp if I remember right, that I started working on today. It hasn't run in many years. It hasn't got a spark. Just for fun I checked the compression before I removed it from tractor. It has 85 lb. I was expecting maybe 30 or 40 lb.

Is there an easy way to check the coil. It's a fly wheel coil like most small single cylinder engines.

Dusty

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917 H, '48 G, '65 D-10 series III "Allis Express"

Posted By: Brian Jasper co. Ia
Date Posted: 21 Jun 2010 at 6:49pm

Now that I put my thinking cap on, Kohler does not have a compression spec for their engines. They want you to do a cylinder leakage test. If you don't have a cylinder leakage gauge, pull the head and see what the top of the piston looks like. You can see where the rings are no longer sealing and allowing oil into the cylinder. The area(s) of the piston where oil is coming up will be washed clean of all carbon.

My experience with the cast iron K series is the cylinders are always worn barrell shaped and I have never seen a crank that didn't need reground. The 301 block can be bored to a std 321 (14hp) piston. I also always used a 341 (16hp) rod. The cranks from 12 to 16 are the same. The connecting rods are the same dimension wise, except the 16hp rod is forged and stronger than the other two. To get the full 14hp from the 12 hp block, you need to also use the larger carb and valves. There is a K361 18hp single cyl, but it's not very common. It has the best camshaft to use in the other smaller engines. The most knowledgeable Kohler K engine folks can be found on, I kind of hate to say this, http://www.ihcubcadet.com - www.ihcubcadet.com . I quit going there due to them not being the nicest folks around. Just beware if you ask anything there that might be in a service manual, you will likely be told to RTFM. (Read the _______ manual. The "F" does not stand for "Fine")

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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford

Posted By: Brian Jasper co. Ia
Date Posted: 21 Jun 2010 at 6:54pm

Dusty, sounds like you have a "Magnum" engine. They used a magneto instead of battery ignition. Disconnect the kill wire and toss that Champion plug in the trash and get an NGK or Autolite plug and see what happens.

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"Any man who thinks he can be happy and prosperous by letting the government take care of him better take a closer look at the American Indian." Henry Ford

Posted By: Dusty MI
Date Posted: 21 Jun 2010 at 7:32pm

Brian, I'm going to start a new thread, I kind of hijacked this one.

Dusty

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917 H, '48 G, '65 D-10 series III "Allis Express"