I'm making plans to get my first pattern plane and am trying to decide on which engine to get. My choices are an OS 120AX and a YS FZ-110S, and an OS FS 120-SE Surpass.

I have a little familiarity with the AX series - my first engine was an AX which I still use daily, and I had a 55AX on a plane that I flew for a week or two then sold, before it really was broken in.

It's my understanding that four strokes (especially YS?) are more difficult to tune. Of course I want the most flying time as I am still new and need stick time. However I want the power, sound, and efficiency of a four stroke. Pattern pilots seem to prefer the YS because of the power-to-weight ratio, and many of them are using the 120AX as well. I listed the OS four stroke as I have had 2 OS engines and have been happy with them.

There really is no one at my field with any experience with YS four strokes. There are a number of Magnum 4 strokes, and many of them are problematic.

I really can't decide, what do you think is the best FOR ME, not just the best.

Thank you much.

Just to add: I did have some issues trying to get the 55AX running right - as did a few other experienced pilots at my field.

The plane is likely to be a Great Planes Venus II or a Piedmont Focus Sport, both recommend a .90 two stroke or a 1.10/1.20 four stroke, and the YS 110 and 120AX are the two most common engines used by pilots in these planes.

Our former club president flew pattern for many years using an OS 61 FSR two stroke with a tuned pipe. When his 60 size Boxer finally died he bought a 2 meter plane and a YS four stroke. He was never happy with the plane or the engine, and eventually sold it to someone who loves it. He prefers the simplicity of a two stroke.

Our current secretary has won the Nationals and he only runs YS.

So, a lot of it really is just personal preference. If I were in your position I'd probably choose the AX. You already are familiar with the AX series, and it saves a bit of money. If you want a four stroke, a Saito 125 is a lightweight and fairly powerful choice.

fixed.

4-Strokes are no more difficult to tune than a 2-stroke. About the only difference is that OCCASIONALLY a 4-stroke may need a valve adjustment. But I've been using them for 20 years and only adjusted valves once - and it's easy to do *IF* you ever have to do it.

That said, YS engines have awesome power, but they can be a little finiky. With your limited experience, I'd stick to an OS120 or Saito 125

To tune A four stroke or A two stroke is the same thing, the YS only has the one extra screw and if you keep your hands off of it then there is no problem, it just regulates how much pressure is being pumped. There are the valves you need to adjust every year or two, well, not adjust but check once in A while. I'm A YS person, own OS and Saito, wouldn't be caught dead buying A Magnum.
Pick and buy the plane before you even think about the engine!! Go over to the glow engine forum and read what is going on with the engines you are thinking about. It's always nice to see what is going on from the people that are really using these engines. With all your trouble with the .55 you may want to go with something being used at your home field so you can learn how to keep the engine running buy A real person.
Good luck!!

I agree with Mike, YS engines can take a bit of experience to get running right and to keep running right. Plus, they are EXPENSIVE!!!

I'm not going to comment on the merits of the way engines run, and the differences between 2 and 4 stroke. But I do want to give you a bit of food for thought. I know that you're still in school and money is a bit tight at times. Most 2-stroke engines can take a lot of abuse when they crash. Heck, I've completely buried a 2-stroke in the dirt and all I did was clean the dirt out of it and was up and running again. Many times a 4-stroke will take SEVERE damage in a crash. Remember that a 4-stroke engine as a lot of delicate parts (valves and valve trains) on the top and out front of the engine, the very places that hit the ground first in a crash. Most times when a 4-stroke crashed the pushrods will need to be replaced, at the very least. We had one at our field last weekend that actually sheared the valves and rocker ams clean off the head, the only thing that engine was good for anymore was a fishing anchor!!!!!

Just something to think about.

Ken

Thanks Ken, sounds like sound advice. Geez that came out weird.

Oh by the way that cleaner solution (windshield fluid and soap) works AMAZING!!!

Seems like the general concensus is the 120AX; I guess it makes the most sense - easy, durable, and less expensive. Of course I want the nicest plane and the best 4 stroke, but I really need to remember I have many, many years to get into bigger and better planes. Any pattern ship with a 120AX will be such an improvement over what I've flown, so that should be enough for at least next season.

I think this is also steering me toward the Venus; it's easier to assemble, can take a beating, less expensive, and comes with great customer service.

I don't know why I think I need something better than a Venus II with a 120AX.

I'd say two things... If you really think you are ready for it, go for the Venus. It is a great flying plane. Your other option might be excellent as well, I've personally have no experience with it. You can't beat great planes though for quality hardware, excellent instructions and amazing customer support.

Go with one of the OS engines. You'd even do just fine with a .61, .75 or .91 2-stroke in the Venus. On the 4-stroke side, there is nothing wrong with YS's. In fact they run EXCELLENT form what I have seen. I do see a lot of guys fighting them sometimes though. As GrayBeard pointed out, the YS nuances could be learned of course but the OS's will be friendlier if you don't want to take on the additional challenge. One of these days I'll find a plane for my .81FS-a.

RCKen also has a good point about 4-strokes getting damaged easily. I have never seen one coe through a crash well, including one of mine... It is hard to see in this picture but the intake pipe is broken and so is the cylinder head. All of that stuff hanging off can be a problem in an impact.

The Focus Sport is a dynamite plane as well. Not sure about the directions but there's a build thread that's been converted to a .doc with color pictures, 80 pages long, with all questions and comments edited out (it's just the build by a very experienced pilot). It's $70 more (shipped) and more difficult to assemble, but not impossible.

Hands down this vote is for the 110s. My preferance is normally to two strokes especially piped two strokes but in the venues where performance 'and' reliability count YS is the only four stroke I have and would ever spend my money on.

Yes you see people sometimes fighting them and there is a good reason for that, They simply did not do the plumbing right in the vast majority of cases and did not follow the plumbing drawing when they set it up. It must be correct and the check valve must be in the right place and pointing in the right direction. Its not that hard to follow directions but you got to look at them.

John

Dang Chuck!!!! You really are A brute!!! If you are going to crash um like that then expect to break um like that!! UGLY!!!! Just little tricks for A YS like John stated, like wrapping your fuel tank with nylon tape to keep from splitting it, A YS is pumping over 7 pounds of pressure into that tank and the tank will expand. I also carry A Diaphram {spelling} with me most the time. It's about the only part that needs replacing once in A while. I had to replace one once, those two scrrews were hell to figure out too!! The price of A YS is now about the same as the other big two so it shouldn't be A money thing anymore, OS and Saito have really gone up. Crashing, no engine is built to take A crash, worse engine damage I have ever seen was on A JETT and any good hit on A gasser is fatal. The next YS I see with A problem right out of the box will be the first one. Problems are usually an operator problem, not an engine problem. I did try to kill my first YS 1.10 FZ by hitting A ground squirrel hole at full throttle, bent crank and other parts not quite straight. That was A high dollar fix. Sucking up all that sand didn't help at all.
DIRECTIONS????? What kinda man needs stinken directions!!!!! We have RCU!!!!
What kinda fun are directions???

I like the four strokes. One reason is the extra grunt you can get from a botched landing or so on. On my dearly departed minnow the OS 91 pulled me out of a few bad situations by just nailing the throttle. The new minnow is getting the YS 110. Of course Im not into the super high rpm speedsters either. Its a trade-off. I wouldnt say I had any more problems tuning the 46fx over the 91 4c. Just keep the rpms in the specified range and dont let the valves float. Just like a car, overevving is hard on the valvetrain. By recommendations in the speed forum I went with the YS and hynes mount. Hopefully Ill have something in the air by the end of this month.

OK, four strokes don't like landing on the rocker cover. However, the one in the photo spent four months buried up the to firewall in a creek bed over the winter and was flying again a week after being found. I've destroyed two 4*60's, two home brew's and a trainer and had several other really hard landings destroying spinners and props. All on four strokes. The only damages to engines was a broken carb mount on a O.S 52 and on a Mag 91. And then the O.S. 52 in the photo. It was the same one that had the carb mount on the back plate broken and later spent the winter in the creek bed. That one came down like a hatchet. The handle was the right wing tip hitting first followed by the rocker cover. The gyser of yellow monokote was awsome. I'm not sure a 2 stroke would have come out any better.

Don

The YS newbie kind who never look at the plumbing drawing when they are setting it up, Thats who

110S and a backup 110FZ Weight 5 pounds 8 ounces, Fuel sometimes 40 and sometimes 45% nitro, one inch short stack no muffler, Propellor 13x11, static RPM 11,000 no valve float, unloaded who knows, takeoff roll from one foot to two from release depending on wind, speed a breathtaking three count from #1 to #2.

John,
I was a YS newbie and did look at the plumbing directions, also had a dozen other people do the same and also try there hand at tuning, to no avail. And this group included several YS diehards.

This was a 140L, never did run more than 3 minutes before it suddenly lost the smoke, got hot and quit. I met another guy at the field with the exact same problem with a 110. I just laughed, wished him luck and walked away.

Funny how I've never had a problem tuning any other engine. I hate to bash YS, but they can take their pumps, regulators and whatever and do you know what with.

I have both the Venus II and the OS 1.20 AX engine. This is a great combination. Our pattern pro has flown it and said it is a fine plane right up and beyond intermediate. The OS starts with one flip, the plane is easy to put together, and the combination flys much better than I can fly it, that's for sure.

Oh you are modest CGYou can fly it with the best of them. Not a healthy breakfast this morning. Eggs, sausage, wheat toast and that nasty old coffee that comes in the blue can. All out of chock full of nuts coffee and have not got to Starbucks yet. The nearest one is about 40 miles away. Going flying this morning, hopefully a couple of flights. Getting the SeaMaster 120 ready for the float fly 5-6 Sept. SkyMasters in Brighton. Take a look at their web site. I am guessing 150 pilots. Fly 7 stations at a time.

The YS FZ-110S is far and away the best engine of the three. If you have somebody at your club that knows how to plumb and tune one (and is willing to teach you), I'd say go for it.

Did you go with a YS engine in your Ice Point pattern plane?

yeah this is the dilemma, I really dont. If i did i would definitely go for the YS and not look back. As far as tuning and running 4 strokes I learned it all on this forum. I had issues for a few days with the 55ax, but so did a guy with 25 years of OS experience, and i got it dialed in myself, with rcu help of course. Would be the same for the YS.

what kind of fuel do the above three engines burn? Will 10% still cut it?

Not for a YS engine. These engines need high nitro to run like they were designed to. I run 25% in my YS 120, but I know others that fly 30% in they YS engines. I tried to run mine on 15% once to see how it performed, and to put it nicely- it didn't.

Ken

All the YS guys say 20-20 minimum, all synthetic.

The others will run on anything.

Nathan King didn't check back after I replied to his post. He's running an O.S. 1.60 FX on his Ice Point. I'm not sure why he suggested you get the YS engine when he didn't choose one himself.

If you read the Venus II thread in the pattern forum, the 1.20 AX is far and away the most popular choice of engine and a great match by all accounts.

No. I chose the OS 1.60 with a pump. If you don't have anybody to show you the ins and outs of YS engines you wouldn't go wrong with the OS 120.

I suggested the YS because the OP was looking to get his hands wet in four stroke engines.... And it is the best engine. Not that the 120 is bad, it's a good choice too. I chose the 1.60 because it's brutally simple and very powerful. The only downside is that the pump tends to flood the engine if you don't get it started right away. After the first flight it's a piece of cake. It even hand starts very easily.