I would think 2sparks per RPM. Not too sure

 

Well, I am not a mechanic, but I think most mower engines are supposed to run in the high 3000's, between say 3600-3900 no load RPM. So try it both ways, if one setting is giving you only say 1800-1900 at full throttle with the blades off, then it must be the other setting .....

 

1 spark to 2 revolutions 4 cycle.

Intake, compression (spark) power, exaust.

2 cycle, 1 spark to 1 revolution

 

That engine fires twice per revolution, once on the compression stroke and once on the exhaust stroke. The only small 4 strokes that fire once per revolution are ones with a distributor and Kohler K series with points. If you set the tach for 1 spark per revolution, the tach is going to show an RPM reading that is half of the actual speed. ED

 

The plug(s) fire once on every revolution. The magneto(s) (coil assembly) is fired off of the flywheel unless the engine has a distributor. It doesn't matter whether it's 2 stroke or 4, small engine or large (this usually only applies to outdoor power equipment engines).

Even the Ford Modular V-8 engines fire on every rev until the computer figures out which stroke the cylinder is on. And yes, they are crank triggered.

 

well now . i was pretty much thinking along the lines of what lgf said.
thought that was pretty much the way it was.ill have to look into it, first chance.

 

Originally posted by EJK2352
That engine fires twice per revolution, once on the compression stroke and once on the exhaust stroke. The only small 4 strokes that fire once per revolution are ones with a distributor and Kohler K series with points. If you set the tach for 1 spark per revolution, the tach is going to show an RPM reading that is half of the actual speed. ED

Yeah that's right the second spark is a waisted spark on the exuats stroke.

 

Well i set the mode on 1 spark per rpm and got four different engines to 3760 under no load without the blades on.

Tryed the 1 spark per two rpms and it was half that and i tryed the 2 sparks 1 rpm and it was half that to.

 

richard ,what u doing in lawncare,man.
what u need is a garrage with several bays.

 

awm, actually I'm working on getting my small engine certificate now.

And Lawngodfather's discription is correct, there is a wasted spark, on every other revolution of the crank.

 

Ok straightened the cable was 2300rpm on low that is correct now, low giving 1500 rpm but full throttle is 3200 still.

 

One spark per two revolutions , Intake-down compression- up ,spark down and up for exhaust . that's why it's a four stroke , takes two revolutions to get four strokes. A two cycle fires once per revolution.

 

And yet Kawasaki(and everyone else) uses a wasted spark system, where coils fire once every crank revolution.