Why do YS 160/170's run so much better on 30% ,or am I just mistaken.What fuel would work best?I still run Powermaster 20/20 is my YS 140 ,but its been my understanding that the bigger ys's thirst for more nitro

The 170 will run just fine on 20%nitro, and probably even less than that. You get more power from 30%, and it really helps on very hot &humid days.

+1

YS's ALL like 30% nitro and my brand preference is CoolPower.....

Not only will they put out more power; they are easier to tune and will idle slower on the higher nitro content fuel.

Just buck up Dave, it ain't like flying gassers....

Switched from 20% to 30% Cool Power for my YS140L one hot & humid summer day at a regional contest. Once the needles were set, I experienced huge power plus a reliable idle and it seemed glow plugs lasted 2 - 3 times longer.

Steve

YS engines are a high performance engine and IMO, any type of high performance engine will perform better, with better quality and higher octane fuel.

I run 30% nitro in all my engines. Only had 2 dead sticks with my YS 140/160's over a ten year period. Glow plugs lasted forever.

I'm now running 175cdi's and still using 30% nitro. They will idle for ages at 1700rpm and then throttle up without any problems.

Most of the flyers i know that are having problems with YS's, are using lower nitro fuel.

I'm positive that the reliable idle and running is helped greatly by using 30% nitro.

All YS's run better on the 30%, not just 160/170/175. Many 2 strokes do also BTW

I think the reason they do is fairly straightforward. Higher nitro is a higher density blend. It can carry more heat away from the engine because of the extra mass. Coupled closely is the fact that higher nitro introduces more oxygen in the combustion chamber and would run lean unless the needle is richened. So, you have higher density (more mass) and more fuel (also more mass), both of which remove heat better. The engine isrequiring a larger amountof fuel per charge and develops maximum HP while maintaining its cool. Bestof all worlds