Try a smaller prop! something like a APC 17x8 or 18x6W or Menz 18x6 if you like wooden props. The 18x8 is probably too much for this new engine. The silicon tubing showed in the pictures is never good for any muffled engine be it two or fourstroke. On a piped twostroke engine it will do no harm. If you must use a 45 degree exhaust deflector then make sure it is the largest possible that would fit on your mufflers exhaust pipe. I believe "Hobbico" at Tower Hobbies has one 45 degree silicone exhaust deflector for 2,7 cu.in. (45cc) engines and that one would probably be big enough for that engine.
Dont know much about Aerosynth3 but I have used Aerosynth2 and now use Aerosave and these are very good and popular syntetic oils but my experience is that a mixture of syntetic and castor oil is better.

Ja Chris. - there is adequate ventilation on that engine, it shouldnt over-heat.. And you are running 17% high quality oil.. hmm.. maybe the 18x8 prop is too much load on the engine as suggested above.. try another brand 18x8 like APC or Wood prop like NX; or go down to 18x6W APC or wood and see if it makes a difference..

good luck!

Thats a nice plane you have! I was running a 19x8 menz without issues in my now sadly demised cap232. You could try adding baffles to channel air thru' the cylinder head.Makes a huge difference as I see the crucial top part of the cylinder is not getting any direct air.The restrictive muffler and long extension could be another source.A shorter length could help or maybe remove the baffle.
Lastly could you be running the engine slightly lean? It becomes a problem as the fuel gets less in the tank and you're pulling into hover.I get that with non pump setups.

Before cutting up my cowl I tried a test run without it - big surprise: the same kind of overheating problem occured!

In fact, I doubt it is really an overheating problem as the temperature here is around 3 degrees Celsius and the engine did not feel hot. What happens is the following:

- After 1 minute warm-up with 3000 the engine revs up to 8200 on full throttle.
- After 1 or 2 minutes full throttle, it drops to 7700.
- After some time in idle for cooling, max rpm gets better, but drops soon if you go back to full throttle.

Obviously, my FS200 does not like continuous full throttle operation. I have no clue what to do here - I did try 20% oil and varying main needle and idle needle adjustments, all with the same result.

I am wondering if this is normal or if I should consider returning the engine back on warranty - anyone else with the same problems out there? On this or another engine?

Cheers,


Christoph

Now switched to an 18x6 prop with good results. Pullout is way better and no obvious overheating issues. Revs around 8700 - 8800 on ground. I will keep it like that for the next 1 or 2 gallons and then retry 18x8.

The only odd thing is that this engine does not seem to rev over 9000 (which is the max indicated by OS) - on downlines and even sometimes in straight flight it starts making sputtering noises in full throttle operation and it would not rev higher than that. Totally different compared to my Saito 100.

Cheers,

Christoph

The pumped version with larger carb and bigger intakevalve will be out soon.
http://www.os-engines.co.jp/english/...sp/fs200s.html

Now that looks like its worth waiting for !

Interesting - Hans, has your FS200 improved over time? I principle I like this engine as it runs very smooth&safe and it starts extremely easy. It could just put out a bit more power. What I am getting is in line with your previous experiences, but off from the tach readings OS claims and what other users have reported here (e.g. like 8700 with an 18x8).

Hi Christoph,

I did not use the enigine that more after last autumn. This year I wil try electrics.

On the jap. site you can find the claims voor the normal version:
http://www.os-engines.co.jp/line_up/fs-200s/index.html

And for the new version
http://www.os-engines.co.jp/2008_02/200sp.pdf

This new version with 5% more power does score a 200rpm less.
Now it become clear wy I was 500rpm off from original claims.

Regards,
Hans

I would add two ounces of castor per gallon. I'm getting ready to take the plunge but the oil leak thing is not something I will tolerate. Maybe a dab of silicone before it's run?

I have just rebuilt an OS 200 for a friend here. It is in a QQ Yak. His was down on power and overheating running a Mej 18x8. When I pulled it down there was nothing too obvious, apart from the bore being glazed and the ring showing signs of scuffing due to the engine having been overheated.

One thing that surprised me when I dis assembled the engine was the amount of oil left in the crank-case and rocker cover. This engine would have been using a fair amount of power due to the drag of the oil circulating around inside. I deglazed the cyl using scotchbrite and checked that it was still true. Fitted new ring, brgs, seals and rocker gasket. I also removed the valves, cleaned off the carbon and lapped them using brasso paste.

The mods I did were to fit a nipple with a larger ID to the carb for the crankcase vent, drill and tap the side of the rocker cover and fitted an extra breather nipple as this engine runs inverted. Even with the extra venting he is getting a small amount of oil from the gudgeon service hole in the back of the crankcase. We will see if this reduces as it beds in the new ring.

I mixed up some new fuel using 15% Klotz supertechniplate with 15% nitro. After a couple of ground runs and 1 flight it is taching at 8000rpm with a mejzlik 18x8, no overheating and consistent running.

My thoughts are there is in-adequate crankcase venilation on this engine and the US instructions call for too high an oil content. (If your engine is under warranty please follow manufacturers advise).

Hi Guys-
I am running the OS 200 mounted about 45 deg. up from inverted and using a Perry VP-30 pump - stock muffler.
Fuel is Powermaster 15%nitro-20% Syn. Oil.
About 2 gallons of fuel max. run through it.
New OS F plug.
Cowl is shrouded to direct air over cylinder with at least 2x exit opening.
Tank is about 6in aft of carb.
For a prop I am using a APC 18-6W.

Question: All I am getting is 8000 rpms tops. Does this sound right? Just seems like it is not developing full power. I did not document it but swear I was getting closer to 9000 rpms when engine was newer.
I have spent a lot of time adjusting mixture and cannot lean it out any further.

Any suggestions on what I can try/look at to get more power?

Perhaps adjust the perry pump? If so, which way - more fuel or less?

Any help appreciated.

Ken

Hi,

I have found out this engine is a torguer engine and dont like to rev. Mine is also getting 7900-8100rpm on a 18x6w but the interesting part is that it easily turns a 18x8w@7600 and a 19x8w@7000rpm without any signs of overheating or fueldraw problems.
However for extreme aerobatic and 3D the 18x6w seems to be the best prop.
On a warbird i would use a 18x8w or 18x10 and 19x8 for scale planes.

Hi Ken,

Just get used to it - this engine does not like to rev and it is not particularly powerful. Performance will get slightly better over time (2 gallons is not enough for a full break-in). This is a reliable and easy to use sports engine, no more, no less.

Best wishes,


Christoph