Why not YS?

[Vincent Judd]

I've read a lot on here about the Saito 4 stroke engines such as the 56 and the 72 and their use in contol line flying.  I haven't come across much talk about the YS 4 stroke engines and was wondering why.  I would think that the YS engines with their pressurization of the fuel system would make a perfect stunt motor. 

What am I missing here?

Vince

[Bill Little]

Do you have a comparison of the respective weights of the engines comparing them to the Saito, etc., that is always a big concern to stunt flyers.

I do not have a direct answer.

Bill <><

[Bob Zambelli]

I think Doug or Steve Moon experimented with the YS 4S engines.

Bob Z.

[Richard Oliver]

The YS is a great engine. 2-3 things come to mind that are issues for the YS for Stunt. It is heavier than all other 4-strokes, cost considerably more and more things to go wrong.
The 1.40 I ran in R/C pattern had pump diaphragm issues and everyone bought an after market brand. With an internal pump and regulator you just have that much more stuff to deal with when it comes to maintenance and repair. The YS is also less forgiving when starting at full throttle, which I think is not good for any 4 stroke in my opinion. You need to let the YS get up to speed a little slower so the tank gets pressurized and the regulator is normalized. This in R/C was done slowly from idle to full throttle.

This is why I still like the old KISS rule.(keep it simple, stupid)
RO

[proparc]

What am I missing here?

Vince
[/quote]

Complexity. That is what you are missing.  Get a pinhole in one of those supercharger lines and kiss your butt goodbye.

[Ralph Wenzel (d)]

I've read a lot on here about the Saito 4 stroke engines such as the 56 and the 72 and their use in contol line flying.  I haven't come across much talk about the YS 4 stroke engines and was wondering why.  I would think that the YS engines with their pressurization of the fuel system would make a perfect stunt motor. 

What am I missing here?

Vince

Despite all the somewhat negative comments, I'm trying a YS FZ.63-S in my Strega. It weighs about 3/4 oz. more than the Saito .56 (both without muffler, so that's a non-issue. Time willl tell.

[Martin Quartim]

Despite all the somewhat negative comments, I'm trying a YS FZ.63-S in my Strega. It weighs about 3/4 oz. more than the Saito .56 (both without muffler, so that's a non-issue. Time willl tell.

I thought about YS FZ.63-S, it sells for $239 @ Central Hobbies and I heard it is has as much power as the Saito 72 but it weighs less. http://www.centralhobbies.com/Engines/ys/YS63s-img.html

I am curious as far as fuel consumption of the YS FZ.63-S, can you tell us?


I can't find the link on RC Universe that talks about the best RPM range for this engine, and I may be mistaken, but I think the RC guys said that the engine likes to run on the 10K to 11K RPM range.


For what is worth, the top 4S flyer n Brazil  use the OS FS-70 Ultimate. They remove the fuel pump and install a venturi. The big advantage of the 70 Ultimate is the fuel consumption, it burns  50% less then the Saito 72 using same prop and rpm.

Martin

[Ralph Wenzel (d)]

Hi MArtin,

My conversations with Central Hobbies suggest that one should prop the engine for a minimum of 10,500 rpm, and that fuel consumption is a miserly ½ oz/min. I presume that this consumption is based on "average" R/C use; not constant full-throttle. I do expect that a 5½ oz tank will be sufficient for the pattern. We'll see.

I would have preferred to use a Tettra Bubbless tank, but there's just no way to put that in a Strega without major front-end surgery.