Since fuel takes some time to begin burning, spark must occur little bit before piston starts power stroke. In most engines, spark occurs when piston moving upward on compression stroke. Most small engines have one ignition timing setting determined by manufacturer, listed in service manual. Possible to adjust timing in many engines.
Some engines (such as Tecumseh and Kohler) have provision for adjusting timing with engine running. Requires timing light. Timing light connected between spark plug and plug wire (in first cylinder of multicylinder engines). Spark plug isn't disconnected. Each time plug fires, timing light will produce flash.
Engines that can't be timed while running usually have spark advance mechanisms. If so, they'll have two marks: a TDC mark, and a timing mark. To adjust timing with engine running, perform following steps:
1)Adjust point gap to manufacturer's specifications. If involves removing flywheel, flywheel have to be replaced before timing checked.
2)Locate timing marks. On some engines, particularly those with self contained magnetos, an inspection plate may have to be removed to expose flywheel timing marks. Recommended that timing marks be accented with chalk to make them easier to see.
3)Install timing light as described above.
4)Start engine, run it at 1,500 rpm. Speed may vary, depending on engine. Consult service manual for proper speed. Best results obtained if tachometer used to determine engine speed.
5)Aim timing light beam at timing marks. As light flashes each time plug fires, light creates strobe effect. Timing marks will appear stationary because only time they're seen is when illuminated by timing light beam. If perfectly aligned, timing okay.
6)Engines with provision for checking timing while running will usually be provide means of adjusting breaker assembly relative to cam while engine running. Method varies depending on engine and ignition system. Externally mounted points, or points of separately mounted magnetos, usually adjusted by loosening point locking screw, rotating point assembly around cam with screwdriver. Other systems are equipped with point adjusting screw. Make adjustments to advance or retard spark until timing marks aligned in light beam.
On a Kohler, adjusting the gap is adjusting the timing a wee insignificant bit. If you want to be technical, making the point gap smaller will advance the timing and wider will retard it. However, that is insignificant, and your timing won't be off simply because the engine will run like scrap anyway with incorrect gap.
Timing on a Kohler K series engine is fixed and solid. It cannot be changed except by changing the camshaft gear alignment with the crank. You have to change the position of the breaker points in relation to the camshaft to adjust timing on any engine. You can time a Tecumseh, and some older Kohlers with Scintilla magnetos (early K-Series) because the entire magneto rotates around the actuating cam for the points.
I wouldn't worry about timing, Noel. Just get your points right according to the book, and make sure they are spotlessly clean.