You will not see outstanding performance numbers when looking at the specs of a motor...#1 you will never be running the motor at those numbers...#2 those numbers don't give best performance and can be interpreted different ways.

The 4 strokes have much more power throughout the range of throttle than the 2 strokes....the 2 strokes on make good power at the top end when running all out.

The 4 strokes have torque in the middle of the throttle band.

Another thing with only one exception the YS 140DZ (fuel Injected motor) cube for cube the 2 strokes will beat the 4 strokes at full throttle. SO


a 72 as you mentioned will not compete with a .61 or .70 2 stroke....but will have about the same weight and top end power of a strong I mean strong 46-50 size 2 stroke.

In fact the plane flying on the 72 will have more power because of the performance in the middle of the throttle band.


Another thing you can't look at a specific prop and rpms to determine power. Props are different and the 4 strokes like bigger props because of the power and grunt in the middle of the throttle.

Also you don't want the 4 strokes turning those high RPMS above 10K they work harder and get better when running down in the 8800-9500 rpm range.

The 2 strokes running in the rpm range don't make power because they get their performance from RPMs...the 4 strokes have it in the grunt category. Take for example an old tractor and a sports car.....the tractor could pull down a building but never hit 100mph.....


One other thing you will find is that the 4 strokes will respond to nitro much better than the 2 strokes. I never run below 20% nitro in the 4 strokes...reason is they run cooler and breathe better...Also the motors really perform as you up the nitro.

Type of Fuel is another issue.....I know there are big loyalties in the fuel department. I would caution you to try a few different ones....and see what you think. Last year I was testing the YS 140DZ and tried almost every fuel I could get my hands on....Wild Cat, Powermaster, Magnum, Cool Power, Excaliber, and so on...I tried all different blends from the 20/20's to pattern to 2 stroke, to you name it....what I settle on for peak performance reliable idle and cool running was the Cool Power 30% Heli Performance fuel. This is the same fuel that Saito recommends for their motors.

I bet if you look at running some of this fuel the performance will come....also as you up the nitro the needle valve becomes less sensitive and because the more nitro the richer the needle is set to get the mixture right.....the more oil flows and the cooler the motor becomes.

I know that Power Master has come up with a new Low Viscosity fuel similar to the Cool Power Heli and now Cool Power is making this same fuel in a 20%.....My guess is conservative but running a stock 20/20 fuel of any brand and then going to the 20% Heli Cool Power the results were over 10% in the performance and then going up to 30% the results were in the 20%+ range.....


The 4 strokes are not for everyone and every application but in the plane you are looking at the the Saito 100 on some 30% cool power heli is what I would run.



Good Luck
Troy Newman
Team JR