Vintage Horticultural and Garden Machinery Club

This old dog leant a new trick. The problem with the Kohler ignition timing was twofold. Firstly, the manual’s instruction was incorrect. It stated that the points should start to open when the flywheel timing mark S was next to the armature plate mark and AFTER that, adjust the points gap to 0.020”. Yet this action altered the ignition timing. The correct method, which I found by reading posts on forums, was to set the gap and THEN adjust it so the points open at S. I originally followed the manual’s method and it resulted in the timing being too advanced by 8 degrees. The engine was difficult to start and in the end, impossible. The second problem was that I did my usual method of honing out pits on the point’s contact surfaces. This resulted in changing the timing and something I was not aware of. When I tried to adjust the points so they open on S, they did not open at all. The fix was to file some material off the heel that goes against the rod that opens the points. However I am going to get a new set of points as they are readily available.

The engine still did not start after the third pull, which is what I like them to do. It did get going in the end though and ran well. Am still not sure if it’s getting enough of the correct fuel/air mixture in the combustion chamber to start easily. Also it’s big heavy lump to pull over, the recent rebore meant it’s still a little tight, the starting handle position just below the handlebars is awkward and the belt clutch on the mower deck creates a lot of friction. All combine into me putting in a lot of effort and still having just one 4 stroke cycle which I hope will fire strongly enough to go to the next cycle. But at least I have a good runner now, the timing was the key and it was David’s original post that set me on course to fix it. It has also made me think that if an engine is mechanically good, the carb appears to function correctly and the spark is 6mm, but it is still a poor starter. Then the timing could be out and from now on am going to check this on ignition systems with points. From what I have read in the forums, wear on certain parts in old engines can effect the ignition timing. If I get this problem on what should be fixed timing and going to use the adjusting of the points gap as a method to getting it to the position the manufacturer’s recommend. Got to be careful the points still have a gap that is close to the recommendation too as otherwise the dwell angle may not be right.