On Friday, February 5, 2016 at 8:18:42 AM UTC-6, CRNG wrote:
On Fri, 5 Feb 2016 09:11:03 -0500, Ed Pawlowski wrote
in

Many years ago my brother and I did some testing on small displacement
air cooled 2 cycle engines. (model aircraft and race car). With regular
lubricants they would run in the 12,000 to 15,000 RPM range. With
synthetics, we could get 15,000 to 18,000 RPM.

Just curious, How did you measure the RPM?

We (small engine repair) used a moving-magnet gauge that directly touched the output shaft. It had a rubber cone to fit the shaft drill-center.