martinoto

Hi there,

I am happy with my OS FS70 Surpass II, which delivers 10,000 to 10,500 RPM on 15% nitro (Wildcat) on an APC 13x6. Problem is, it is in the heavy side. Power is amazing, thou, and I am now a 4s fan since this engine (my first 4s). I have now also a FS91 Surpass II and a new alpha series .81 (yes, you probably saw my post swearing I wouldn't expend that amount of money in this engine, I know....). Anyway...

My queestion:
I am now in the process of getting a new YS FZ63S, which also claims to turn te same prop at around 10,500, although with 20% nitro fuel. And I read here that the Alpha 56 also delivers around 10,000 RPM with the APC 13x6 with much less nitro. Both YS and Alpha are ligther than my trusty Surpass, so there is a good reason to get any of them, because even at the same power they would use less of that power moving the engine itself, right?

But I wonder, why too many of you consider the YS the "non plus ultra" of the pack if it delivers what seems to be the same power? Or is it? Does it means that the same RPM with the same prop IS NOT NECCESARILLY the same power? I will get one of those anyway, but honestly I wonder if I will note the difference...

Thanks a lot and regards.

Martin

Harry Lagman

Martin, you've let the cat out of the bag now!

You've got all the main players in the fourstroke .60 - .91 bracket except Saito. A benchmark test is mandatory: you must put these engines to the test and report the results! You may bust a few myths in the process.

I can tell you from experience that the YS .63S will turn a 13 x 6 at about 500 - 700 rpm more than an OS Surpass 2 .70 can. I've flown two examples of the same model - one with a YS .63S and the other with the OS Surpass 2 .70 and the YS is most definitely more powerful. An OS .56a may get close to the .70 Surpass but it won't match a YS .63.

Don M.

My Feedback: (5)

I just sold off 2 - YS .63's that I had for about 5 years. Nothing wrong with them just went electric for the smaller stuff. The .70 may ( but I doubt it ) have the same power as a .63 and the .81 probably does but I can tell you NOTHING will match the .63 for speed of transition from idle to full. I had these engines for 5 years and the speed at which they transitioned still scared me. I thought they would blow up - but they never did

liquid_TR

martinoto,

YS63 is in a class of its own.. As Don M said, no engine will match the transition speed and upline torque of a YS.
Also I saw with my own eyes the YS63 on 20% nitro turned a 13x6 APC at over 11400 on second tank. thats more than 1000 RPM than 56FSa or 70 Surpass.

YS63 with 20% nitro and 12x8 or 11x10 is a very frightening pattern power plant.

YS63 on 20% nitro is about as powerful as an theoretical saito 85 or something.
Its power is just shy of 91 surpass and probably in the same neighbourhood of 81FSa.

I'd go for YS power and transition on a pattern ship, if I could afford the 20% nitro fuel. In alternative Im going for 2 stroke power with tuned pipe with 5-10% nitro.

Waco

My Feedback: (265)

with high performance comes headaces that can drive you nuts, I had a couple of YS engines and when they run you can not beat them in performance but but if you ever have problems they can drive you nuts trying to figure out the problem. It was the only engine make that made me want to cuss.

w8ye

My Feedback: (16)

Why you can always send your Y-S in for service and for $165 they will make it run as good as new again for a couple more years.

liquid_TR

you know YS is as basic as any other glow engine. no special stuff. dont let the regulator scare you. its just a silicon diaphram..

If anything is wrong with the YS its the same suspects as an OS or a saito.

if something is not right, its probably a problem with fuel delivery, fuel itself or the glow plug...

If there is, just fix the problem yourself or let one of your experienced buddies do it for you.. for free..

martinoto

Thanks all of you for the answers.

Liquid TR: 11,400 RPM is definitely more than my 70 Surpass II could do, so I guess the YS 63 has more power after all.

However, I saw a 91 Surpass turning an APC 15x6 close to 10,000 at 10% nitro. Mine is not break.in yet, so I couldn't tried by myself. I don't expect the YS 63 turns a 15x6, as I don't expect it either turn a 14x6 at a decent RPM. My Surpass 70 does a good job with an APC 14x6 at 10% also.

I will get the YS63 in a couple of weeks, and I will try every conbination with the props I have in hand.

Thanks and regards

Martin

w8ye

My Feedback: (16)

While my Y-S engine had the smoothest idle, fastest transition and greatest power of any four stroke that size I had ever owned . . . .

There is a tremendous design philosophy difference between a Y-S engine and a OS, Saito, or Magnum engine. People that say that there isn't a difference, are not completely familiar with the internals of a Y-S engine.

First of all the other brands do not have a sealed crankcase.

The Y-S engines have an extra seal in the front of the crankcase behind the front bearing. Also the carb(s) has a seal between them (or rather the two halves). There is also the requirement of an external check valve, an air tight fuel tank, and a myriad of tubing running here and there to make the fuel system run correctly. An air leak or malfunction of any of these will cause the engine to be erratic. In the regulator mentioned there is also a piddle valve that can stick or wear out in addition to the thin diaphragm mentioned. One needs a complete understanding of the whole system to be able to properly trouble shoot it. The "S" versions have a valve on the intake pushrod housing.

In addition, the 120AC and 91/110 engines have an air chamber on the rear of the cylinder with a thin paper gasket that is very touchy to get assembled without the bottom side raising up away from the seal area.

Even the rocker cover gasket seal is critical on a Y-S.

The engine and fuel system must be air tight.

blw

My Feedback: (3)

A good way to view this subject is to look at how many spare engines the pattern guys take with them to a meet. The guys running OS engines take one or two spares, and the YS crowd normally has up to 10 spare engines for the weekend.

asmund

I fix my YS myself, I have had my 110 completely into atoms and replaced the oil seal and main bearing (it runs like new again in case anyone wonders). I always thought this was a very complicated engine, but everyone comfortably with normal 4 strokes will have no probles fixing an YS themselves. Yes there are a few more parts, but it`s really not that difficult. But one has to know some basics about how a YS operates, like W8ye says, even the valve cover gasket is critical.
There`s no way I`m sending off my engine halfway around the globe (and wait for it for ages) and pay 165$ for a little maintenance

martinoto

BLW, I find hard to believe that someone get 10 spare (quite expensive) engines to any contest, even if sponsored...

But anyway, the intention of the post was more likely to compare real power, in terms of RPM with same prop. I know there are lots of other issues to consider, like engine cost, fuel cost, reliability, tunning complexity, costs of parts, etc.

To be honest, in my case the fuel cost is what worries me more. But my point was, if (from I read in several posts) those three engines could turn and APC 13x6 at or around 10K, then why bother? The answers I got showed me that this is not quite true, and that the 56 Alpha could be at 10K, the 70 Surpass II delivers 10,500 (that I know for a fact) and that YS63 could turn the same prop at more thatn 11 + K, which means it has more power.

I for sure will get the YS, and I will probably get an alpha 56. Then I will see by my own test, considering my very basic tunning skills, which I hope will not spoil the final observations.

Then, with the final results, anyone could choice whatever he likes in terms of spare parts, or aquisition costs, or fuel costs, or as in my case, true weight.

Thanks and regards

Martin

Waco

My Feedback: (265)

martinoto, I just think we just giving you a warning that YS engines are a little more complex to set up and get tuned right than the saito, OS and other 4-strokes, I wished someone would have warned me and saved me the $. For sport flying with easy set up and running stay with the regular 4-strokes, but than you sound like the guy who has to learn himself. Now if you are a competition flyer than YS cannot be beat for performance.

martinoto

Waco, I agree.
I know YS represents more maintenance and tunning time.

For instance, my Surpass started easily the very first time (with a counter-flipping to the spinner) once primmed with 4 -5 hand turns at WOT. And I still use the same procedure today. Never have to touch anything but the needle (and sometimes not even the needle).

That is the reason I am asking. If the power is the same, why bother to cope with complexity?

Thanks and regards.

blw

My Feedback: (3)

Yes, you are right about what you meant. Didn't mean to step on any toes with my comments.

asmund

The power is NOT the same. The YS 62 WILL eat the OS 56 alive. The YS is not only bigger displacement, but also supercharged. The OS 70 which is of greater displacement will also fall short of the YS, because the supercharging more than makes up for a little lacking in displacement.

I do not find the YS more difficult to tune, the high speed needle tunes just like every other engine`s and the low speed needle is an airbleed and tunes just like every other airbleed, meaning the OPPOSITE way of a "normal" low end needle (turning inn RICHENS and turning out LEANS the mixture)
The regulator seldoms need any adjusting and if it does it tunes like the high speed needle, only it regulates the middle rpm range (turning out richens the mid range and turning in leans the midrange) Easy peasy

Once my YS is tuned and adjusted I just fly and fly and............. only occationally tweakes the high speed needle a few clicks to adjust for weather changes

Ahh, I forgot. 30% fuel is EXTREMELY expensive here in Norway, but if absolute max power is not required I retune my 110 and run 15% (it still outperforms similar sized fourstrokes)

I even ran it on FAI fuel on one session just for the hell of it and it still ran ok, not terrible powerful but for relaxed flying around in the sky it worked fine, never quit or anything.

martinoto

BLW, no problem, you didn't step on any toe.

Thanks and regards