THis is real confusing. I've recently purchase a Storm EX 120 pattern ship. Of the four 120's that are still available out their, which is far more dependable, more power and less headaches. More importanly, what are the major differences between these engines. We can keep this online or you can email me at: [email protected] - thanks is advance, Steve

Go for the YS 140 Sport or a used YS 140 FZ.

You forgot one - the YS1.20SF

YS History

These are all evolutions of the same motor I cover what I know about them in the order they came out. For the most part each iteration had more power until the 120SC.

120SF--Original YS 120 4 stoke

120SF--Big valve this increased performance a little bit.

120AC--a hopped up version of the 120. Had the air box on the back. This was the real power house of the 120's. It made huge mongo power. The main issue with the 120AC was its weight. It was about 2ozs heavier than the others...both because the motor was beefed up structurally and it had the extra metal of the Air chamber. This motor was really the work horse of the pattern community for a long time. The Dr J's and up through even the Sequels and Prophecy were mostly flown with this motor. But as I said before weight was an issue.

120NC and 120SC--This is where YS branched out into the sport modeler market. The top of the line competition pilots gravitated to the SC for its increased power over the 120AC. This motor also reduced weight. The air box was now under the valve cover like most of the motors today....A little less boost than the AC but if run properly more power. The NC was basically the same motor but detuned a little not so hopped up that life was superb on them. They were the Non-Chambered motors. Many of the non FAI pilots ran this 120NC motor for a long time as it was more beans than the SF but not by a bunch and had similar docile operation qualities.

120SC became a motor that was tough on parts. The piston was lightened beyond belief and the motor was running on the ragged edge but making huge power. This is the motor than many people got upset about as it was not the easiest to run....Backfire and bam you just bought some parts. If it was treated well and never run lean the SC was a great motor...But run it out of gas, Yep thats a lean run and it would bark, talk, spit and break things left and right. It was really a motor aimed at the top guys in competition that had lots of experience running the YS motors. In the mean time FAI and Pattern rules stepped back from the 1.20 size limit and removed all engine displacement limits. This gave Yamada the opportunity to increase the displacement of the motor in order to get more power rather than work on the latest hop ups to the 120's. The reason the 120 had so many versions was the desire for more power more power....and YS gave it to the modelers in the form of high performance versions of the same 120. Now the 140FZ was born. More cubes always is an advantage.

140FZ--This motor was equal in and in most cases more power than the 120SC but since it did it with more cubes rather than the high compression hop ups...It became a honey. Somewhere along this time frame the air bleed throttle barrel screw arrived...I think on the SC's first then it carried over the 140FZ....Now all motors with the air bleed screw on the throttle barrel were designated FZ so they shortly released a 120FZ basically an NC with a different throttle barrel. The 140FZ was one of the most docile and easy to run YS motors of all. It was not overly compressed would run a long time and make great power.

120FZ similar to the 120NC as it was a Non Chambered motor but it had the throttle barrel bleed screw and the backplate YS motor mount. The new look of the YS motor mount was less functional in terms of the performance of the motor. Sure pistons may have changed along the way and as always YS tinkers with better parts...but most all the parts are interchangeable on the 120's...The AC is the one with the most physical parts changes.

140L Released about the same time as the 120FZ maybe a touch earlier was the Limited edition motor that stayed with us for 4 years+. This motor used some of the hop ups that Yamada learned on the 120's to give some more beans to the 140FZ....Basically this motor was intended again for that top level F3A competition flyer. A new Motor mount from YS had similar principles to the Hyde mount. The 140L was designed for the competition segment and the 120FZ was the sport guys motor or the pattern flyer on a budget.

Then comes the 140DZ....new fuel injection system. Means Huge power increases...all of the other power increases were small..150-200 here 300 there. The Dingo broke the mold. Changing the the way cold fuel is injected into the motor and the lack of the pressure system that was a YS trademark....the motor was truly a revolution in YS motors.

Once the DZ came to favor the 140L started loose its luster as the top competition motor so YS in the USA released the 140FZ Sport...Basically its a 140FZ with some of the power improvements of the 140L like a bigger carb and more robust piston. This motor was targeted at that Sport crowd and was priced to replace the 120's. Now the Sport guys can get the 140 power and performance for the price they paid for their 120's.

So the current crop is the 140DZ and the 140Sport. On the future horizon maybe a 160DZ. Some top pilots have been testing the idea in a new motor...But I don't know the details on any release info...My guess is late next year.

I know this is a little too much info but I think it covers the YS evolution...perhaps there are some other major changes in this mix but I can't think of them right now.

Troy

Troy, thanks for such formative info - that essay of yours really spells the YS history for me as for 4-stroke. One question, their is a 120AC and a 120FZ on ebay. Also their is a 120NC but in this particular auction, in the body of the description, the guy refers to this engine as an SC. Can you check this out on ebay and contact offline at: [email protected] and let me know your thoughts. question, would I be ok if I took the AC over the FZ - I'm really a balls-to-the-wall flier and speed is my game BUT I take care of my engines - thanks again for your info, Steve

Hey Steve,
Do you really want to run a 4-stroke??? :-)
If you really just want lots of horsepower get a Webra 1.60 or even the Webra 1.45. The new Mintor 1.70 looks great, too.
Just food for thought - pattern rules!!

-Will

Hey Will, good to hear from you. I just pickup a STorm EX with YS 120. I figured its time to jump in and get my feet wet since I've been with 60 size for the last 30 years. Anyhow, I had originally ask the question concerning the many versions of the 120's and wanted to hear feedback. One gentleman really spelled it out in describing the upswingSo in referrence to the Webra's, the fewer moving parts, the less headaches? I've read countless horror stories on 4-strokes but at the same time, very positive comments. I guess what it all boils down to is care and maintance. Once in while, you'll get a lemon but not often with YS motors. Are you currently running Webra motors?

Steve

Any lemons are taken care of really well these days with YS performance as the importer. Some guys were not happy before with the original Importer...I always had very good service from them as well. But Rich Verano at YS Perf goes the extra mile for everybody with a YS motor. I have heard stories of crash damage being fixed at N/C and then the motor being shipped back 2nd day air.....This is for Competition and Sport flyers alike.

They are really first rate. I'm in a unique position as a field rep for YS Perf. Everytime I wear the YS shirt at event or help some guy with a YS motor, I get bombarded with how well the Service Dept handled the guys motor.

I think in this hobby the biggest thing you can say about a company is how well they support the product. All motors, radios, or kits will have troubles from time to time. And the way the company steps to the plate and solves the problem is what makes the difference in choosing one product over another.

At YS Perf, they treat all their customers with the same attention to detail. They make sure that when that guy looks into a new motor his experience with them will help him choose another one of their products. I know Dave Shadel monitors the RCU YS group and is very good at answering Q's and solving problems.

The question is do you get the same level service and support from that other Engine company (who ever it is?). Or do they tell you that you used a bad fuel or ran it lean and that is why the chrome flaked off the sleeve. With YS you have the guys that are in charge of the bottom line also the same guys talking to you on the phone. Makes a huge difference in terms of service and support. They are responsible for the growth of the company and they are all for treating the customer as they would want to be treated.

Don't get me wrong there are some good motors out there. But for me mainly the Service and relationship a company has with their customers is the reason to use their products.


Troy

Hi Steve,
Personally, I've had great success with a minimum of effort (maintenance) with 2-strokes. My First Bully 1.20 I flew for more than 1100 flights with the only maintenance being the occasional plug change. I have not encountered the alleged rear bearing problem with The OS 1.40, but I make sure it is well cooled. Central Hobbies has a deal for the new Webra 1.60 (with the MC carb I think) right now. I've also heard/read good things about the Mintor engines. I'd like one just because I think they look cool. I just wanted to give you a 2-stroke perspective. I've always liked YS engines and wish they'd make a big 2-stroke...maybe someday.
Lastly, I really don't think there are very many 'lemons' anymore - quality control is pretty good these days with CNC machining. I can tell you that out of the box; the OS carbs are set pretty close - the Bully carbs have all been way off - especially the low end.
Happy shopping - just buy one of everything... :-)
-Will

How would an OS120SurpassIII w/pump compare to the "original" YS120SF you mention?

I'm going to use one on a all-balsa Typhoon 909 I'm finishing.


Saludos!