I'm going to get a 2 meter pattern plane and am trying to decide on a 2 or 4 stroke engine.

What are the benefits/drawbacks of each?

Why are so many pilots switching to 2 stroke engines?

Won't a 2 stroke use considerably more fuel than a 4 stroke? It seems they would since they turn about the same rpm...

I'd be very interested in comments from those who have used both.

Thank you.

Four stroke definately....They burn alot of feul aswell, but have more torque than two strokes, and the big prop swinging slowly causes drag and slows you down on the downlines. Most two strokes tend to rev up and down lines, so you go faster. Also, the latest YS four strokes ara as powerfull as similar sized two strokes. However, they are expensive, and if you damage it, it can be expensive to fix.
2 Strokes are simpler, and have the same, if not a little more power as four strokes. They don't have as much low end torque though.
I would go with the YS 140 DZ. It is said to run very nicely, smoothely, with little vibration, and matches the OS 140.
Robert.

My 2C!!!
Robert.

I will have to agree with the use of 4 strokes. Unless you are looking to run the engine at the high limit most of the time, a 2 stroke just doesn't have the low end torque to swing a big propeller.

Depends on the plane and your budget. For my Focus for next year I am using a two stroke. The airframe has a enough drag built in, tends to be a little heavy and likes the power. For my Prophecy I will keep my YS. A clean plane like this is too fast with a two stroke.
Fuel consumption is similiar since two cycle are loafing most of the time. Many are switching for simplicity and cost with the added benefit of less weight and more power.
Watch what people are flying at your local contest learn from others experience.

The bit about 2 strokes having less torque is not true for the dedicated 2 stroke pattern engines from Webra and OS. There are different setups but the more common 2 stroke configurations turn a 17x12 APC at 7800-8200. The only 4 stroke that can do this is the YS DZ, though most DZ users generally prefer to run lower diameter at a higher rpm.

One wouldn't really want to run any of the above engines in older pattern designs. There are practical limits to the old saying, "You can't have too much horsepower".

Guys, I have to agree with the last post. Your views on 2 strokes are about 2 generations late !

most of the europeans competitors have switched to 2 strokes, with good reasons ! An OS 1.40 2 strokes turn the same, if not bigger, props that an YS 1.40, for $150 less, and much more simplicity.

Bernard

One thing thats not being addressed in the thought process is the difference in the cost of fuel. The Webra will run fine on 15% while at the Nats this year many of the competitors using the YS DZ were forced to run 30% Heli fuel. Do the math and you will see that the Webra is alot cheaper to own as well as operate. With the new style wide bodys and the larger diameter props run on the Webra downlines aren't a problem. I for 1 am selling all my YS engines and replacing them with the Webra 1.45 2 stroke. One other thing is that I believe the Webra runs about as efficiently as the DZ.

price is also a factor a YS DZ while a nice engine I'm sure....is pretty expensive.... I have three OS 140 RX and I love them, powerful and a good set-up at a fraction of the cost, and a lot less part to change don't the road. I had the YS 140 L before and still have a couple of YS, they are great but the cost of repair while not very high....around 100.00 us per shot....but the engine had to be send in ...that mean no engine for a while, I keep very few parts for my OS, and don't have to send them for a YS guru to work on them.

Now if YS want to send me three DZ for free.....I'm more then willing to pay for tax....

Powerful and simple set-up I say 2 strokes.

Daniel D.

I new I was going to be shot down

Robert,

That was not my intention......I never said that I didn't like them, they are just too expensive in both original price and parts.

I like to have three fully equipped airplanes, and they have to be well built with lite stuff and equipment, so I have to manage the money intelligently.

Cheers, Daniel D.

Hey Robert I didn't mean to shoot you down either. You could do a lot worse than a YS. One thing that the DZ has over the 2 strokes is throttle transition. Its impressive. I have to admit that I had great success with my YS 140 L. Good debate hope to hear more. Mike

One more thought:
Your 4-stroke choice is limited to the YS (although OS built a prototype 1.40SP I don't think they're going to produce it).
There are several 2-stroke choices from the very inexpensive OS 1.60 or ST2300 to the very expensive EFI series.

Hey I was just messing around.....I saw alot more 2 Strokes than you may think!!!

.

Im a 2 stroke fan, the 140 rx's we are running on coolpower 5% nitro, hattori pipes... thats cheap running as the rule is, the more nitro you use the more money its gunna suck! For bang for your buck I dont think you can beat the 2 stokes.. Its all just an opinion though, really they are all capable of the job, its just down to what youve had experience with...

I'm flicking YS 1.40's and a OS 1.40.in 2x2's at the mo'
The OS 2-stroker is far more thirsty than the YS's yet uses cheaper fuel and basically requiers zero fiddleling... but then again is more noisy. Both use Hatori's. After having a love hate relationship with YS over the years I was hoping for more from the OS. Right now it dosn't compare to the YS's...
sure it's powerful but so are the 4 bangers.

I suppose if I'd be using 2-strokes for years I'd feel a little freaked by a temprimental YS in the nose. It all ultimately depends on personal choice.

PS. I unscrewed the pump screw 1.5 turns on the OS. Much much better than standard setting.