So a question then to MotorGeek, what is a TRUE was to test jetting scientifically then other than just how it runs and rides?

There is not any real scientific equipment that I have found that can tell you when a two stroke has the best power air fuel ratio.  Instruments that can measure performance like stop watches, radar guns with acceleration plotting ability, dynos, timing clocks and speed traps at the drag strip are some instruments than can tell you when you are making optimum power.  You just have to make enough runs with different jetting to see which one runs best.   

An 02 sensor like we use on 4 strokes will not tell you what mixture will make the most power. 

An egt gage will not tell you when your engine is making the best power.   Every engine has a different egt where it make the most power.

A water temp gage or a spark plug base temperature gage will not tell you when you are making the most power.

An air flow meter and a precise fuel flow gage like we use on the dyno will not tell you when you have the mixture that makes best power. 

Reading a spark plug will not tell you when you have the mixture that makes best power. 

Looking at the top of the piston will not tell you when  you have the mixture that makes best power

Trying different main jets on the on the dyno or roll on side by side drag racing  on a long paved steep up hill will quickly tell you if you have the best power main jet.


As I lean the main jet and power increases I look at the piston crowns and spark plugs for indications of detonation and overheating of the piston crown .   A well developed engine package will not usually hurt the piston before you reach the jet that will make max power and max acceleration for brief periods of full throttle.  An engine that has a good working cooling system and a properly designed piston will allow the engine to run at max power for longer time periods before reaching critical temperatures. 

I wish there was a jetting for dummies instrument but I have not seen or used one.  You have to use all of your 5 senses and painful past experience to tune two strokes.