Hi all, I figure this forum is the best one to answer a few questions about this engine. I bought it from an
estate sale, it was installed in a Top flite P-39 (red box) that was unfinished. It looks basically brand new,
and I'm sure it never flew, no oil stains or exaust, no rust, no scoring, turns over nicely, it probably ran
one or two tanks of fuel on the bench. I'm not a pattern flier and have no experience with pipes, so my questions are:

1- Would this engine run good on a standard muffler (assuming I can find one).
2- How much power would it give compared to a modern day .61 to .75 range.
3- How easy is it to set up (is it hassle free?).

I fly mostly 60 size warbirds, super sportster and the likes. I'm considering putting it on the Bay,
comments?

1) I have a Mecoa muffler on a YS61 side exhuast, www.mecoa.com, part number 930-61. I believe it is an OS61FSR muffler. The holes need to be elongated a couple of thousandths of an inch to match the YS holes.
2)Certainly equal.
3)It is easy. Is there such a thing as hassle free? It uses a pressurized fuel system versus a muffler pressured system.

You won't get anything for the engine on eBay, nobody likes these engines. Could I send you my address and I will take it off your hands? Oops, my nose is growing!

Couple other advantages of the YS engines. One really does not half to worry about fuel tank/carb placement/arrangement. One can put the fuel tank over the CG if wanted due to the pressurized fuel system. Once tuned properly... The engine really doesn't care what position it is in no matter what you throw at it in the air. The needle setting stay the same through the entire tank of fuel. Great power as Airbusdrvr pointed out. Can turn a good size prop too. The biggest thing to remember though about YS engines is do not use a after run oil that is petroleum based as it will cause the seals in the regulator to swell. Good engine

You call the engine a "YS 61S" ...Could you post a picture of your engine?? "YS 61S" is not technically a "real" name and it could easily be confused between two very different engines...

There is a YS 61ST2 which is a helicopter engine and not really "designed" for aircraft use...(I've heard of folks using them on aircraft but they are apparently low on power)...

Or there is the YS 61FS which is designed as a Pattern Aircraft engine...(YS0080)...A wonderful engine as the others have stated...I have several of the Rear Exhaust versions..

Here are a couple of photos...The Left is the ST-2 Helicopter version....The photo on the Right is the FS which is the Pattern engine...

Hi Full Rudder,
I'm going to recommend that you sell the YS and replace it with a nice user-friendly OS .75AX or similar engine.
YS engines are powerful, durable, reliable. However, they can be a PITA for the inexperienced operator. The fuel system is pressurized to about 6 psi. Great for tank placement flexibility and fuel delivery. Lousy if you have ANY minor leaks in the system and many commercial fuel tanks will blow up like a ballon if not reinforced. They tend to require more break-in before they will run reliably through the rpm range (they are not 'out-of-the-box' OS mount it and fly it engines). The brass pressure regulator, which MAY require minor initial adjustment and then should be left untouched, is a screw driver magnet for many. Just a few reasons to consider selling.

-Will B.

My sentiments exactly. He should box it up and send it to me. Heck, I'll even pay the shipping and include a good bottle of the best Canadian drink he wants.

You know Aibusdrvr I almost shipped the engine to you today but you convinced me to keep it
I'm well versed in RC engines just not familiar with these pumped/piped ones. Thanks for the muffler tip,
and BTW I saw one almost NIB sell for 160$ last weekend.... nice try!

Impactit:
Now for the goof, not knowing I did put in a bit of after run oil (petroleum based[:@]) about 2 weeks ago wanting to protect it
from rust, now what are the chances that it's affected? Anything I can do (dissasemble to clean or other) to
prevent damage?

Navav2002, it's a YS61FS as shown in your picture, pattern side exaust, I called it a YS61S because thats
all I could read on it, thanks for your input.

Flywilly, your opinion is basically what I had in mind before posting, but I'm still undecided, but your
opinion does reflect the fact that this engine might not be the best thing for my kind of flying.
So Airbusdrvr how many cases of my favorite are we talking about?

Tanks all for responding.

As long as you didn't flood the engine with oil.... you should be ok. The best thing you could do is flush the crank case a couple of times with with some fresh fuel to break down the oil you put in it. Put some fresh fuel down the carb. Crank over the engine "slowly" by hand with the glow plug out. Drain the fuel and repeat. Oil it with non petroleum based oil (Ultra Oil found here: http://www.pspec.com/details.asp?ProdID=40&category=7 Very good after run oil and lasts a long time too! Great for all engines.) I would not take the engine apart unless you plan on replacing (at the least) the regulator gaskets. Worse case, you might half to replace the regulator plunger, diaphragm, reg. housing gaskets. Either way... it is worth it!

Impaciq, you wrote, "The biggest thing to remember though about YS engines is do not use a after run oil that is petroleum based as it will cause the seals in the regulator to swell." I suppose this is a dumb question, but what about Hobbico after run oil? I suppose Marvel Mystery Oil is also petroleum based? Is there a product similar to Ultra Oil available locally, ie auto parts store?

I'd recommend Ultra Oil...But have heard of folks using Mobil-1 Synthetic Motor Oil...

Petroleum based after-run oils cause the silicon diaphragm in the pressure regulator to swell and operate erratically. Remove the regulator housing and flush with methanol (or just regular fuel) rinse both sides of the diaphragm. Put the regulator and parts in a separate ziplock bag until you are ready to run the engine. I would probably try to find another diaphragm to purchase, too. I would probably just replace the diaphragm right before you run the engine (and flush all the after-run oil out of it).
The good news is that the diaphragm is quite inexpensive and I think they are still readily available.
Get some Ultra oil
-Will

One more comment...If your going to be running the engine on a regular basis...I've seen it suggested you don't really need an after run oil with the quality and additives in todays fuels...

I rely on Ultra Oil primarily because most of my engines will be sitting a while before the aircraft are built...And since I re-building most all of my engines I'm using it as an "assembly lube"...

Once I get some plaines in the air and am flying on a regular basis I plan to cut back on the after run oil...

Just My .02

Chuck

Keep the YS and learn how to tune it properly. They really are set and forget engines. I got my first YS 5 or 6 years ago and it was a well used 60FR and since then have switched to all YS engines even in my heli. If I ever have to fiddle with the settings on my engines I know somethign is wrong.

As for the pressurized fuel system, I sold my YS 1.40DZ because I prefer the pressurized fuel system. Use good fuel line and aluminum fuel Ts and also wrap your taank with a few turns of fiberglass reinforced tape and don't worry about it.

The biggest thing with the YS is to make your changes and let teh engine run 10 - 20 seconds to tell you what it wants. Most of the YS engines I have bought have been from people who said they could not get them to run right. To date, every single engine has tuned perfectly for me.

Just my opinion.

I can not comment on the Hobbico oil as I have never used it or had a bottle of it but the Marvel oil is petroleum based. You can use oil that is 100% synthetic as mentioned here already (mobile 1) with good results. Just make sure it is 100% synthetic and get the lowest viscosity oil you can if going the automobile oil route. I believe 5w30 is the lowest one can get over the counter. IT will not take much either! I have always used Ultra Oil and one bottle really does last a long time.

0W-20 Mobile 1 will work. This is the lowest viscocity Mobile 1 made.



NO MARVEL MYSTERY OIL!!!!!!!!!!


Troy Newman
Team YS