Crackhead

I have a new FS 2.00 with abotu 2 gallons of 15% fuel thru it and it seems to be a real dog. I've tried everything from the recommended 18x10 to a 17x8 and it performance is hardly better than my 12 yr old FS 1.20. The 16x6 benches 8500 rpm's but runs very rough and won't hardly get my 11lb Funtana S90 over stall. The 17x8 or 18x8 get in the 7800 range and run very smooth but just don't seem to pull it very well. The thing I find the most disappointing is the Saito 1.80's Ive seen on this airframe yank it around like a rag doll. I'm a long time OS customer but after dropping almost $500 on this engine I'm really thinking about selling it and buying the Saito. Do you have any suggestions for before I go to this sad extreme? Is it possible the ring hasn't seated fully yet? Compression isn't what I think it should be either. what prop did OS get the 9000 rpm benchmark with?

Bax

My Feedback: (11)

Peak power is at 9,000 RPM with whatever size propeller it takes to get that RPM. You won't necessarily be able to fly any kind of airplane with that prop at that RPM. That's just the RPM where the peak horsepower is generated.

If the engine lacks power, it can be from quite a number of reasons: low compression, leaky valves, bad carburetor adjustment, faults in the carburetor/fuel system, badly-made valve train components, and so on. We'd need to see the engine before we can make any evaluation.

Crackhead

What steps do you recommend that I try before sending it in for service. Would you think that the valves are out of adjustment and causing the poor runnig at higher rpms? Does it sound to you like the ring may not have seated yet? Do you feel that this engine should turn an 18x10 or 17x8 prop faster? I would like to try something more before I give up on this engine. I just don't know if my expectations are too high, if there is something wrong with this engine or if this design just doesn't make the power I'm looking for. I would be very happy if theres something I can do to fix this myself.

Crackhead

I spoke to a tech at Hobby Services and he said they use a benchmark of 8600 rpms with an 18x6 wood prop.

Fasthobbys1

My Feedback: (11)

I have a new 200 and found similar results only getting 7100 with a vess 18x6,and 8400 with a 17x6,airbourne engine had NO power and quit at 1/2-3/4 throttle last flight.Mounted on an Aeroworks 90-120 Yak

Bax

My Feedback: (11)

The question is what airplane and what are your expectations? If the engine is turning in the mid-8,000's and the model doesn't fly the way you like it to, then you plainly have the wrong propeller. If you need more airspeed, you'll likely have to add pitch and reduce diameter. If you need more vertical, you may need to reduce pitch and add diameter. Remember, if you add pitch, you must reduce diameter to keep the engine running in the same RPM range.

The key to any engine is to match the combination of airframe, engine, and propeller. Then, and only then, will you get the desired performance. You will have to work with different propellers to see which is the best one for your model. Even same-size propellers of different makers can have radially-different performance. It's all "try and see".

Crackhead

Well, I have to say I tried at least 9 different props at $18 to $24 each. I now own a great stock of props that the OS 200 doesn't like (based strictly on static rpm's), and I have no other engine to mate them to. At least my LHS loves me.

The thing that rubs me wrong at this point is, OS is not very co-operative about benchmarks. This is something I really don't understand. If they would at least say "hey we got X rpm's with X prop using X fuel, you would have a place to start. Instead they say recommended props - "16x12-15, 16.5x12-14, 17x10-13, 18x6-12, 20x8, 13x11, 13x12, 14x10, 14x11, 15x8, 16x6, 16x7, 17x6". I expect they spend thousands and thousands of dollars on R&D but hide the results and expect me to spend all my money re-inventing the wheel. If I bought 1 of each of the recommended props per OS's website and Tower Hobbies it would cost me $350+ pre tax. That's like 75% of the price of the engine.

My 15 year old FS 1.20 spun a 16x6 APC prop at 9300 rpm's yesterday on YS 20/20 fuel. The FS 2.00 would turn about 8300 rpm's and sounded like I was trying to kill it.


The bottom line for me is, hang a for sale sign on the FS 2.00 and let soemone with more time than me work on it while I buy from a manufacturer that isn't afraid to tell you what to expect from their products. In the last 20 years I have used almost exclusively OS engines, but I have to say after the two experiences I have had with OS product support, I'm done with OS.


I wan't you to know Bax, I'm not aiming this at you, and I appreciate all the help you give in this forum. This is a post the president of OS needs to read. If he doesn't get the message, he needs to have his marketing people explain to him the cost of getting a new customer versus keeping an old one. He has managed to sell his competitors product to me, for them.

selnekav

Hi,
unfortunately i must agree with you although i really miss OS as it was when i first started on that Hobby 25 years ago.....
and i am still have hope....

i was very loyal customer for years, and that was especially as i have never encounter any quality or performance problem in any of my old OS engines... they worked like swiss clock and the idle was incridble we always said on our runway that OS is actually electric engine that works on nitro...

but those days passed away.... .. i think that the change point was after the SF series production stops, and the FX was born.

i must say that even today 20 years after i am abosulutly sure that My OS-SF 40 worked better then today AX... at least at idle.....

Ho.. and the OS 46 VF what an engine....

nostalgia ...

Pippin

I've got an ASP 180FS rated at 2.9HP. I have an O.S. 200 too. The 200 is rated at 2.9HP as well but slightly better and smoother than the 180FS. The pumped version is rated at 3.0HP. The 180FS turns a MAS Classic 16x10 happily. The MAS K 16x8 is good for slower planes.

I would not recommend going down to 16x6 on the O.S. Pitch is too low to fly a normal sports plane nicely. A 16x6 might be fine on a Piper.

The O.S. 200 turns a 18x8. But again, I would opt for more pitch and less dia, depending on model and needs. 16x10-12.

If you want more power, you should get the O.S. 55GT TS. It's rated at 5.5HP. The O.S. BGX would be another option, if you want to use glow fuel.