I don't use YS 20/20 but I have always used a Sullivan 6oz RST clunk tank with no problems for my 72.  My 72 uses about the same amount of fuel as my Supertigre 51.  4 strokes are economical. 

DAN BANJOCK USES POWERMASTER 10-22 ON HIS SATO 72 POWERED VISTA.DON'T USE LESS THEN 20 % OIL AS THE ENGINE WILL BEGIN TO DISINTEGRATE.HE BLEW THE GEAR ON HIS CAMSHAFT.HE USED MY SATO THE REST OF THE SEASON.
PUT YOUR ENGINE ON A TEST STAND AND MAKE SHORE OIL IS DRIPPING FROM THE BREATHER NIPPLE.IF IT IS NOT DON'T                                             
 USE THE FUEL.
HE USES A 331 VENTURE WITH A SUPERTIGER NEEDELVALVE ASSEMBLY ON MUFFLER PRESSURE.
HE USES A REV-UP 14-5 AS A BASE PROP.A APC 14-5 WORKS WELL BUT MAKES THE AIRPLANE NOSE HEAVY.
DAN GAVE ME PERMISSION TO GIVE OUT THIS INFORMATION.
STEPHEN DINERMAN

Ok I will use powermaster 10/22 and a 6oz. clunk tank. Pressure or no pressure to the tank?

Forum looks different, I have to get used to it.  I use suction on my 4 strokes and uniflow on my 2 strokes. As to the YS Bob, that was a light hearted joke. The engine is very complex and requires a very high level of expertise in ANY application. 

If you are curious, ask Windy for his video with the YS on it. I have also run them courtesy of the RC boys, ("hey guys look at this, he's going to hand start it") . 

The YS has a stranglehold on the 2 meter F3A scene, the OS Max 91 Surpass has come to dominate the Senior Pattern Association class, (their classic).  Saito dominates everything else.  If I was going to rock and roll in F3A,(hint hint) I would go with the Saito FA-150, (hint hint). I would bank on my not having to dead-stick against his better flying to pull out a win LOL.

What is a roque venturi ? can you post a picture ? is it available in the USA? $?

Roque is the name of one of the best Brazilian flyer, pronounces HOCKY . He started to fly 4S many many many years ago and after burning a lot of fuel testing different designs he come up with a venturi which do a soft break.

We are fine tuning the dimensions of the unit and soon I will be selling it worldwide.

Martin

Martin, I watched your video of your Roque equipped Saito 72.  As far as I'm concerned, you nailed it.  If you need an engine run better than that, more than likely you just can't fly!!!

Me too... Awesome... Sure don't understand how a venturi can make a 4 stroke do that but it seems to work. Looking forward for more information.

Really starting to appreciate the grunt of 4 strokes now that I have a much better idea of how to make them run.