The cdi engines are very economical. My 175cdi's use 300ml for 13mins. flying.

I know that YS engines have always been popular with the Pattern crowd. Is anyone using them for 3D?

ys, yes they are powerfull but will throw a prop fast. also some of them don't have a idel needle either. it's makes them hard to tune and the pump is a pain sometimes when dirt gets in it. they can drip fuel from them making a mess when the spring or diaphram is not closed. i had a ys .45 2 stroke that ran super,but the four stroke i had,i sold and bought a evo 100 to replace it because i didn't like it. also they run on 20% fuel mix. the other engines run on 10% fine. if you want power,which we all do ,you must pay for it........

Small correction, Pattern rules have no power source limits excepting the voltage of an E model. The only limits are weight and size of the model, and weight is measured with batteries on E models but wo fuel for wet power models

No reason why not....Throttle response is as good as a walbro gas carb's

Except for 3D I suggest something less expensive to operate, such as an OS GT 22 or 33, DLE20, 30, or 35, and several other gas engines,

As already pointed out in post #48.

Actually, the ones without the lowspeed needle were very easy to tune. One of my .53s had no LS needle, I called Dave Shadel to order to order the carb barrel with the LS needle and he said, "don't waste your money" so I didn't. Setting it with the regulator did the trick perfectly.

Ditto

LOL.... Here is a Direct comparison...between a popular 2-stroke and a ys 110 4stroke...
What do you think???

OS 1.20 AX
https://www.youtube.com/watch?v=BVH_Yi377eY

YS110
https://www.youtube.com/watch?v=7H0Nxt9XYxs

They only throw props when they are set too lean as will all other four strokes that I have seen.

I've only ever had a 4-stroke chuck a prop once. From then on I use a locknut with a spinner nut. No more thrown props. I don't know why anyone runs a 4-stroke glow engine without a doubled up prop nut.

I've owned every YS four-stroke (120, 140, 160, 170,etc) that was made and have flown them exclusively in pattern competition for almost 20 years. There is nothing that can compete with YS for power or reliability. The engines require some discipline on adjustment, fuel selection, and operating habits that other engines do not, but for those who treat them well, the reward is there.
Of course, I've come across many people who owned them briefly, and had bad luck with them, but invariably they were mistreated in some way. Some of my favorites...
1) Using fuel with castor oil ...converts any YS into a hunk of junk
2) Doing an extensive break-in on the bench...also turns a $600 engine into a hunk of junk
3) Running an improper high-speed needle setting, usually too lean.
4) Refusing to acknowledge that there is also a low-speed adjustment and a diaphragm adjustment. (usually takes me 5 minutes to adjust either and make someone really happy)
5) Running the wrong prop...usually not enough prop and over-speeding the engine, resulting in cam gear damage (if lucky)
6) Any number of plumbing problems, usually not following instructions
...and so on.
It isn't a simple engine, but hard-driving, consistent, reliable performance isn't easy.
I sold all my YS engines to go electric, simply because of the simplicity and going from $5 per flight to $1 per flight in fuel costs.

Still the very best engines out there. No exceptions. OS are next best, but more in a "sport" performance class.

AP

I have had a bunch of YS 2 and 4 stroke engines over the last 25+ years. I have run them in pattern planes and helis and modern 3D and funfly planes. I have had good luck but on two occasions I had engines I could just not get to run well, a .63 four stroke and a 1.10 four stroke. Both were in highly acrobatic aircraft and both received TLC at the hands of the YS parts and service gang before i gave up on them. So IMHO, you could get a lemon. YS power output is legendary. YS is the king of "set and forget". YS heli engines are outstanding. YS owned pattern until electric took over. But I would not choose a YS four stroke for a 3D plane that is going to be spending a great deal of time in a hover or high alpha at mid throttle settings.

Fair enough.
I lived in a pattern world where almost all my buddies had "an engine in the plane, an engine at YS Service, and an engine on UPS somewhere in between".

On the flip side, I have never missed a contest because of engine trouble since starting to fly pattern with YS 4-strokes in 1995 (flew YS 2-S before that). I don't recall EVER dead-sticking during a contest round. I only ever had one engine in play, and never sent a engine to YS except for the new 160DZ that was seized in the box.
In practice flights, I remember dead-sticking twice...once because the prop got loose and stripped the cam gear, and another time with the new 170DZ on maiden flight with a bad klunk.
I always rebuilt my engines myself every 250-300 flights, putting in new bearings, o-rings, gaskets, diaphragm. Every 500+ flights, I might replace the piston ring or sleeve, maybe hone/clean the valves/seats, and replace the high speed needle.
I ran fuels that were 100% synthetic, varied from 10% to 30% nitro, and NEVER ran the engines dry at end of day, and NEVER used any after-run oils. I ran only YS plugs, some years I ran OS plugs.
So, based on that track record, I would trust a YS (if I had set it up, of course).

AP

Hey thanks for a great response. I too flew the YS two strokes in F3A comp and remember when those big four strokes hit the scene. Great engines! Now here's the real tricky question, when someone in your club sees your YS engines running, and asks if they should get one too, what do you say? I have been asked that so many times over the years! I always told them that they could not buy a better engine, but that the engines would not tolerate poor running condition or tuning, essentially they are not forgiving in that regard. I have seen a lot of guys screw up their YS engines in no time. I think it has a lot to do with the sensitivity of the YS needle valve. Everyone learns on engines where they can twist the needles 1/2 turn either way when tuning them, try that with your YS and you've got trouble. And that is why I think people fear YS engines.

Didn't read it

I can't say my experience with YS has been entirely pleasent. The rear bearing failed after a few months so I sent it back to YS Japan (missing one comp) and they "fixed" it under warranty but they didn't change the crankcase as you can see see the little divots that the bits of bearing made right up to where the crank sealing ring runs.

A few months later the CDI sensor began to intermittantly fail. Of course even though it was still under warranty it seemed that 12 month warranty really means they'll only look at it once. It took ages to pinpoint the fault which required a lot of buying parts and swapping them out to try and see and missed a major comp in the process.


Since then it's been a dream run for the past 3 years, I rebuild it every couple of hundred flights, clean and gap the spark plug every 50 flights, the current plug has 145 flights on it and it goes hard. One or two clicks of the needle every few months, or a tweak of the reg if I drop down to sea level (I'm nearly 3000ft). My unpumped OS .75AX ran straight out of the box and has been far less of a hassle initially, so I wouldn't say YS engines are idiot proof out of the box. Anyone who's never had to adjust the regulator (on a YS DZ at least) either got really lucky or their engine isn't running right and they can't tell....

1) There is nothing wrong with using a small amount of castor in a YS. I run 1% in all my engines and i have never had a problem. It is a benefit.
4) On the DZ engines, the regulator is the low speed adjustment. No seperate needle. 2 adjustments.

I mix my own fuel. It costs me $1.32 per flight and that's running 30% nitro. And i don't need to buy a generator, fuel for the generator and cart it to the field for charging batteries. I fuel up, fly, land, fuel up and fly again.

It doesn't get much simpler than that.

YS make a sport range of engines also, but for high performance you can't go past the DZ range.

My first YS was the FZ140 in 2000 and i have 2 x FZ63's.

I also have 2 of all the DZ's from the 140 to the 175cdi. All these have ran straight out of the box, only adjusting after the break in flights except for my second 175 which had a faulty back plate sensor. This was replaced under warranty.
I have had ignition box problems, but once i figured out how to support the sensor lead to stop it from breaking, i haven't had any more issues.

I would expect a 75AX to be easier to operate than a DZ. It's a much simpler engine.

In 14 years i have never missed a comp. due to engine problems. I always take 2 models to a comp, but have only had to use my back up once. That was when number 1 crashed in practise due to battery failure.
I have only had 2 dead sticks during a comp. The first was when a small piece of fuel tube blocked the needle valve. The second was in when my throttle servo failed. So none of these are engine related.

Not bad for 14 years. I consider that i have had a very good run with YS's and don't see why this will change any time soon.

I can't wait now for my 2 x 185cdi's to arrive.

GO YS.

Everyone is quoting the present sporting code. The rules that applied were from the late 80s. I think it was a ploy from OS who had their Roots supercharged 1.20 at the time and was not top dog anymore. It does not apply today, but the history of why.

I've had many people ask me if they should buy a YS when they saw mine run. I usually ask them if they need the performance and try to re-direct them to a Saito or OS. They typically don't buy the YS, unless they seem committed to contesting and really want to invest and learn. I sold a DZ170 and later an older 140L to guys who really wanted to try them, neither having any experience. In both cases, I literally wrote a 5-page instruction manual with all my notes and hard lessons from all those years and gave them some briefing. In the case of the 140L, the gentleman flew at my field so I was able to help him learn about it and he runs it like a champ. Everyone else at the field who owns a YS go to him now for enlightenment when I'm not around.

In response to Drac1's note, fair enough. Not sure what 1% castor does for you one way or the other. I have seen too many people run a new YS on regular all-or-blend castor fuel from the local hobby shop and ruin the engine that way. It isn't fatal, but just expensive to replace the liner, piston, valves, head, and ring that have lost tolerance, and I don't know of any technology short of very costly acid etching to remove the shellac left by the castor. The YS will be happy in the hottest of weather with a bit more nitro to keep it cool. The legendary higher flash point of castor isn't needed like it was in ballistic pattern engines of 30 years ago.

Anyway, the YS is a b****-mistress, and like the V-12 Merlins of Reno racing, require some extra TLC and know-how to deliver a winning contest. No short-cuts or easy passes on this one.

AP

There was a long time when engine displacement was the limiting factor, to .61 cuin, since that's all there was for quite a long time. OS introduced one of the sweetest running 4 strokes, their 60 4 stroke, but it just didn't compare to the 60 2 strokes of the day in output. Then in mid-late 70's Fox came out with his .78 and later with his .74 2 stroke, thinking that was the future for Pattern. A real shame since that may have been the begining of the end for Fox, having tied up so much resource in that development

Until the OS and YS 4s120's were allowed to compete as equivalents to all the piped 2s 60's circa 1982. Folks quickly realized the YS was a bit stronger and more advantageous (read low end grunt with larger props) than the piped 60's of the day so fairly quickly after that engine displacement and type were eliminated as limiting factors in FAI/F3A and AMA quickly followed suit.

The history lesson is off topic a bit, but it may be pertinent.

My experience with YS 4strokes has been a mixed bag too. I still have an FZ63 which is one of the weetest runners I've ever had, with simple field manners. Same can be said for the FZ120; still have one of them in storage, but is all locked up with gunk.

On the other hand, I had a 140L and I always chuckle at how apt the suffix is....L for limited. I had mine for a total of three runs; it died lean on its second run wiping out the front end of my brand new Alliance with all its specially custom molded fancy cooling ducting. Pissed me off something awful..... Took engine off the plane, mounted it on a stand, and it proceeded to do exactly the same routine. Packed it back up and sent it in to Richard for service. He said the regulating section was completely replaced since the original was sticky causing fuel flow problems. Sold it immediately after and have not purchased any of the newer stuff.

But of course, since discovering how good some gas engines in this power band have become, there is absolutely no reason to ever go to 4 strokes any time soon.....

Castor oil can be gummy if left for a long time.. Some parts don't like it (ie: regulators) but there is no way on this earth someone is going to convince me that castor oil will ruin a piston, liner, valves, guides, lifters, or any mechanical part of an engine. It just won't happen.

The first 4 strokes were novelties. OS with the .60, one of my favorites, and the early Saitos,use to be in those Hobby Shack ads. They were suppose to be quiet. FAI first allowed .90 4 strokes but it was lobbied to the 1.20s. Enya, and OS were the players of the naturally aspirated still stuffed into .60 2 stroke planes; then the YS came out, then the OS supercharged and 2 strokes were doomed from then on.