125 K301 head

Fri Nov 05, 2010 9:48 am

The 125 I just got has stripped threads on the spark plug. Past owner had a helicoil done. Its ok but I'm not sure the plug is in far enough. I sourced a replacement head. Then I found out about high and low boss heads. And that Kohler made a few different head designs. My exising head appears to be a low boss with the spark plug centered between the valves. The replacement head I have appears to be the newer design with the plug over the exhaust valve. I found a description of this head.

The newest style head manufactured by Kohler is much like the previous one, but has the spark plug located directly over the exhaust valve. There are two reasons why Kohler did this:

It prevents cold-starting incoming raw fuel from fouling the spark plug.
It helps to produce more engine power and torque by retaining the majority of the combustion heat in one area.

If I use this replacement head the tins on top the K301 will not match up with the spark plug hole. Has anyone else done a head replacement like this. I can cut the tin a bit to make the plug hole match the tin.

Re: 125 K301 head

Sat Nov 06, 2010 4:18 pm

My 122 had the low boss head on it when I got it. Although they put a few pieces of tin work on it, it looks like just cutting the muffler heat shield would suffice.


Re: 125 K301 head

Sat Dec 11, 2010 9:36 am

I have a 301 head for sale. I send send you a photo if interested. It's in great shape Threads are perfect.