Khizer

Hi guys,

I am strictly a 2- stroke person now thinking to switch to 4-strokes.
As per my 15 year experiance O.S. 2-stroke are reliable and powerful . But as I see most of the posts regarding 3D planes people either talk about Y.S or Saito. Aren`t O.S 4-strokes good for 3D ? As far as I know technologically these are the most advanced engines with features like super charger, electronic fuel injection especially I think FS 70 Ultimate is the most powerful in its class what do you people say?

STG

My Feedback: (26)

For the weight I think the YS63 or Saito 82 are the leaders in this size. I think the advantage to the 82 is it can run a larger prop and the advantage of the 63 is that it have a pressurized/regulated fuel system. A lot of people will say the 82 is easier to tune and less finicky. For the weight I think the only 2 stroke that I know of that will run with these motors is the Jett76L, but then you are talking worse fuel consumption and more $$$.

As far as I understand, most OS 4 stokes do not put out as much power for their weight. These underpowered 4 strokes do run great and get the good gas mileage that a lot of people incorrectly attribute to all 4 strokes.

drumbum

My Feedback: (1)

The OS 4s are very reliable. but have a weight disadvantage when compared to the saitos.The saitos are also very reliable, they do take a little more tweaking (but not much) after break in.. the YS`s are the best power weight ratio of them all.. but if you are not an experiences YS person tuning may be frustrating (very) they take patence. but once set up correctly they too are very reliable..

Hope this helps

raideron

My Feedback: (1)

I agree.. OS and Mag 4c are very reliable and good engines, But they do
have a weight/HP disadvantages against the likes of a Saito and the power
house YS engines of the same size, but they are cheaper... YS's can be a bit
finicky on tuning, But once set and the fuel to it kept clean... IMO there is NO
comparison powerwise per cubes, and also the responsiveness of this engine.

powerlines

I have had the YS63, Satio .72 .82 and now just got the 100... The YS was SUPER powerful.. BUT I COULD not keep it running. I acted like it was overheating and just would not stay running. I have had 3 Satios and I have loved them all. The .82 was about as strong as the YS but. The ys would turn up QUICK. I loved that. I tried all I could do with the motor. Now the 100 I have is just getting broke in and I love it. They are easy to tune and hold the settings. All you do if fly, fill and charge.. That is it. .I love that.. I will make do with the power loss...

GOOD LUCK



LATER

Dealspeed

My Feedback: (17)

Right now OS is definetly behind the pack with there four strokes, But i Think OS is about to catch up.
The new OS FS 70 Has a great desighn and honestly considering it has a built in pump systum the damn things really light and has pretty decent HP.
Give it time and OS may just surprise us with something really sweet

seanychen

My Feedback: (4)

The OS 70 Ultimate would've been an able contender w/ YS 63 had they designed it right. It's still in Beta form as far as I'm concerned. Its power is less than YS 63, weighs more, costs more, and transition is impossible to get right for most people. Over half the owner including myself have problem w/ the 70 Ultimate.

For a .40 size plane, YS 63 or Saito 82 are the way to go. YS 63 if you want more rpm; Saito 82 if you want larger prop.

STG

My Feedback: (26)

Khizer,

If you are going to fly with fuel that has no or very low nitro you may have better luck with the OS. What do you 4 saito & YS 4 stroke guys think?

Luke 3D returns

Yep you need at least 10% nitro in saitos and 15% in YSes. Ive seen OSes run well on 5%

I personally think saitos are the best all rounders - they use cheaper fuel than ys but are ligther and more powerful than OS

Khizer

Yes the problem is actually nitro. I run all my engines on 20 % pure caster oil and 80 % methnol. Nitro-methane is not available at an affordable price in my country.

Well if performing 3D manoeuvres how much a 4-stroke help? Does anyone of you have any experiance of 91 FX or 108 FSR in Funtana VS Y.S. 110 FZ ?

I ve seen some videos of CA wide body 60 with 91 FX doing low level hovering and High alpha harriers very well although the acceleration and responsiveness of 91 FX ( I own 2, 91 FXs) is not extra ordinary.

STG

My Feedback: (26)

It is funny you bring this up as we have just been reflecting on this in the "Funtana 90 what engine thread".

http://www.rcuniverse.com/forum/m_26...tm.htm#2877103 see pages 20-22 on.

Are you asking about the F90 or the f40?

The 108FSR has about the same power as the YS110, but is 6 to 8oz heavier with the muffler. Also because the YS has a pressurized and very smart cam operated regulator that tells it to only let fuel(perfect mixture) flow at certain times during the cycle it cannot be matched for spool up performance. Idle to full throttle is almost instantaneous.

The 108FSR runs longer on cheaper fuel and can be made to out perform the YS buy running a tunned muffler like the Turbo Jett at the cost of mileage. I have found that in order to keep my spool up snappy I need to lean the high and low range out more than the motor can reliably draw it, so I have went to a VP30 perry pump. (found the same thing on the FX1.6)

If you are looking for a low or no nitro motor to power the F90 iand Unlimited power go with the 1.6FX 10.5 pounds

If you are looking for the same on a F40 I think the O.S. 91 4 stroke or Magnum would be good. The .91Fx would also be a good choice, but I would be looking to make the muffler as light as possible and under prop it with something like a 13 x6 prop.

One thing I almost forgot to mention is that the YS would not like the 20% pure castor oil so YS is out of the running.

drumbum

My Feedback: (1)

I hear ya. me and a friend had a heck of a time with one (brand new) Never got it running right. I think everyone in the club tried.. turned out it had a bad pump... he traded it in at the LHS for a SAITO 82.. That was and still is a sweet running engine.. it almost is as powerfull as my OS 91 surpass

Luke 3D returns

For 3d the fourstokes are miles better than two strokes.

However khizer although one of your problems is lack of nitro availability a much bigger problem is the fact that you use straight 20% castor fuel. You have to use synthetic fuel to reduce clogging up the valves.

My advice would be if you cant get hold of nitro or synthetic fuel to either go two-stroke or electric.

drumbum

My Feedback: (1)

OH NO dont get SPACEWALKER started[X(]

shaunrbell

My Feedback: (4)

I could be wrong but I don't think anyone has ever got a OS Ultimate 70 to run LOL! That would include myself. OS ended up taking it back after trying to fix it. I'm using a Saito .82 and pretty happy. It maybe low tech, but a least it runs and pulls strong.

Shaun Bell

STG

My Feedback: (26)

[sm=lol.gif][sm=thumbup.gif]

FlooredCOBRA

I have both a Saito 100 and a YS 120 FZ and both are really good engines. The Saito 100 was my first 4 stroke engine and it was easy to tune and never stalled on me. Very reliable engine.

Later I wanted more power and got the YS 120. I heard many things about the tuning being finiky with YS but got it anyways. I figure it cant be that bad and wanted to learn about YS. Now I am hooked on YS and don't think I would buy any other engine but YS. I never touched the regulator just low and high end needles and it runs awesome. For this engine to be my first YS I was very easy to tune. Then again maybe I got lucky with the presets on the engine. But the way it came I don't see how it would have been hard to tune.

Transition from idle to wide open is violent, I love it. Now I want to get a faster servo for my throttle. I am just using a standard servo. With a faster servo for throttle I can take more advantage of the throttle response I think. As far as fuel consumption the YS is not to bad.

strulag

My Feedback: (-1)

How's the throttle response on the Saitos?

Angus Balfour

OS have best build quality, YS are the most powerful, Saito, couldn't say.

I’d like to know why some people find YS hard to set up. Honestly, they are a complete doddle. Open main needle to 2 turns, prime, put on glow and off you go. In my experience people only run into problems when they start to tinker with them when they don't know what they are doing.

Angus, YS devotee

joeb102072

My Feedback: (9)

I cant speak for why people think YS's are finiky I have had as much of an issue getting a Saito to idle as I have had getting a YS to transition properly. And my definition of issue really isnt anything monumental a turn here and a listen there. While I do agree that OS are the most trouble free engines available thats as far as my praise goes for OS. They are a good engine at a decent price. Saitos while just as good running have the weight advantage. To me thats what I feel is the big difference. And then there is YS, of course I am prejudice toward YS but there is a reason why. They are the best no other can match their power to weight ratio. Why people put the Saito .82 against the YS .63 and they say you can swing a bigger prop with the saito. Well Duhhhh of course you can. Put a YS .91 against a Saito .82 and see which one swings a bigger prop. My point isnt to bash Saito but show how much more superior YS is to the other 4 Strokers. Weather its a .63 or the 1.60DZ you can put your tanks on CG with out having to run a pump that alone seals the deal with many people who are finiky about their 3D set ups. Although the only downside to a YS is its initial cost. But IMO you get what you pay for.

Barry Cazier

My Feedback: (17)

Careful what you say. The Saito 82 is a very fine engine. It may whip a YS91. I can't say for sure because I don't have a YS 91 but I have a Saito 82. I also have 5 YS engines. FZ110. I only have 3 running, others are new in box. But I think they are finiky to tune. Every one. I have spent many an hour tweaking so that they won't deadstick. I think I finally have them figured out and they are now very reliable. However, I really like the Saitos also and they have never deadsticked on me. I have 2 100s and 2 82. In their class, 100 and 82 they are unquestionalbly the best. And DUH, why doesn't YS make and 82? Right now in that class, Saito is the best. And I can't tell ANY difference between throttle response between the Saito and the YS. Both are excellent.
Thanks,
Barry

rlipsett

ys engines have an interesting characteristic in that they run normally asperated at idle up too about 2000 rpms after that they run fuel injection. They tune up easy like an os engine by setting both needles to factory recommended starting points and adjusting the high end needle then the the low end idle. the tricky part comes in the middle. You should never have to touch the low end again but when the engine comes up a few clicks above idle you have to listen for the engine running lean or loading up. The pressure regulator has to be adjusted for this mid range turn in to lower and lean and out to richen. I usually start at 1/4 turn and as it gets close refine it to finer settings. after mid is adjusted reset the high end and you never have to fiddlewith it again except on first flight of day to adjust high end for temperature and humidity changes just a few clicks. and yearly adjusting of valve clearance. a truly remarkable engine

joeb102072

My Feedback: (9)

I too agree with the remarkable power delivery of a YS. Which is why I disagree with the above statment of the Saito .82 being close to power as a YS .91 and throttle response being just as quick. All I can say is run them side to side then see what happens. One of 2 things will result the YS will out perform the saito by alot or if the Saito pulls ahead you have found an poorly tuned YS. AS for thrust to weight ratios yes the Saito is lighter however that ratio makes no difference the 2 engines for the YS is much more powerful than its difference in weight to the saito. The fuel delivery system on a YS isnt necessarily fuel injected although it is refered to as that. All YS's except for the DZ have a regulator in them that controls the pressure of the fuel delivery into the carburator. This pressure system is activated when the fuel tank lines and engine are bleed of all air and pressurizes. It is that pressure that forces the fuel into the engine making the it appear to be fuel injected. The only 2 engines YS has right now that are truly fuel injected and run off a fuel pump is the 1.40DZ and the 1.60DZ. There is a huge misconception that the metal box on the back of the ever so famous 1.10 is the fuel pump when in fact all its just an air plenum box. Just FYI.

emnm79

My Feedback: (5)

lol, the guys at my lhs told me my ys110 was a "knock-off" of an os motor!!! ahhh!!! [X(][X(][X(]

barry i think ys doesnt have one that size because the 63 has enough power for those class planes? and 82 n/a vs 91 s/c, lmao.

oh yea, joe, its not just the pressure in the lines that forces fuel mix in, air is drawn into the case by the upstroke, and then shot back through the carb into the intake during downstroke, something along those lines

joeb102072

My Feedback: (9)

Yes you are on the right track my explanation only went so far as to get the fuel from the tank to the engine. As for it entering the engine it uses the downstroke of the piston to push the mixture into the cylinder through a double sided disc valve. As a sort of "Super Charger effect" Like a mix of 2 and 4 stroke engines combined.