Avoid your typical after run oil in the YS. The seals will be ruined with petroleum based ARO. You should buy a Harry Higley book on engines Jacked69.

http://www.hobbylinc.com/htm/hig/hig...source=froogle

Expect overhauls more frequent than you're Saito, especially on the pump diaphram. One big winner on YS is you can put the fuel tank anywhere in the plane, and it will draw fuel. You can tach it 2,000-3,000 higher than your Saito too. Don't forget to readjust your CG with the engine swapping chores.

Here is a good website to answer more questions you will have on the YS.

http://www.geistware.com/rcmodeling/glowpower/ysfaq.htm

Personally, I'd put a .91 on it, not a .63. Either way, these are thirsty engines. YS 20/20 fuel isn't cheap.

YS 63FZ: 1/2 oz per minute

YS 91FZ: 1.1 oz per minute

YS 120FZ: 1.5 oz per minute

YS 140L: 1.5 oz per minute

YS 140DZ: with venturi restrictor- 1.75 oz per minute