What are these engines???

LAST EDITED ON Jul-07-04 AT 04:00 PM (CDT)
 
Today I noticed my OS 25 engines are not all the same. Never noticed this before. The OS Max web page does not list thees engines. All 3 of these OS Max 25 engines are different. Does anyone know anything about these engines?

1. The engine on the bottom right says OS 25.
2. The engine on the Top Center says OS 25 SF.
3. The engine on the bottom left says OS 25.

Engine 2 and 3 appear to have the same size piston, the crankcases are both different but about the same size. Both engines have crankshaft bearings, roller or needle not shure which. They will both turn a 10x6 prop and appear to be about equal in power and speed to a Fox 36X. A 10x4 prop is an excellent stunt prop for this engine on my Ringmaster.

Engine 1 has a smaller piston than the other 2 engines. The crankcase is smaller and has no roller bearings. It runs best with a 9x5 prop on my Ringmaster but seems to be a little bit under powered. It flies so slow with a 10x4 prop its hard to get the Ringmaster in the air. Line tension is very low its about like flying a 1/2a airplane with a 10x4 prop. Once the airplane has reached full speed it will do a large loop but I am afraid to try a tight loop with the 10x4 it will probably stall out it almost stalls out with this prop. I tried an 8x6 prop the engine RPM is up but the airplane speed has not increased very much. I tried a 9x5 prop airplane speed is much better, I can do loops, figure 8, anything I want but it seems to be very slow.

Question....is engine 1 what everyone calls the FP engine?

Question...what is engine 3?

Question....is engine 2 the old version of the new OS Max 25 FX?

Check out the landing gear on the Ringmaster. I was having a lot of trouble landing this airplane it jumped like a frog every time the wheels toughed the ground. I soldered a wire between the 2 wheels and now it makes perfect landings. Fuel tank pressure line fixed my engine problem too.

Am I to assume that you did try a 10-4 prop on a half A engine?

Bill

Gary,
None of those are the *FP* version. The bushing bearing one on the Ringmaster is an old *S* series like the 35S. Did you try a 9-6 on that one? You say you have used an 8-6, 9-5 and 10-4. If the 9-5 is working, but too slow, you should try a 9-6 of the same brand (APC?). If they are different types of props (Muanufacturers) then you might or might not see much difference.
Bill <><

Gary,

The engine on the lower left (#3) appears to be an OS Max .25FSR. The version I have has an iron piston and steel sleeve. People have said it is a little more powerful than the FP, which is a little more powerful than the older S. (These might be the other two engines you have shown.) The engines you are showing would not all perform the same even if they were taken right out of the box.

I have my .25FSR in a SuperClown, which is very similar to the Ringmaster. I have been trying MA 9x5, 9x6, BY&O 10x4 and have a few APCs to try as soon as I get a chicken stick.... This engine has plenty too much power for this plane, so I have detuned it somewhat. When it gets too windy to practice stunt, sometimes it is fun to switch to a high pitched prop, fill it up with fuel with a little less oil, then turn in the needle valve and practice "Foxberg" racing.

The bearings used in the FSR I believe are ball bearings, not roller or needle bearings. I don't know for SURE, because I haven't had to take mine apart yet....

Happy Max'ing,

The .25FSR is a twin BB engine, and quite a bit more powerful (when run in its proper RPM range) than a .25FP. I've lost track of how many other OS .25 BB engines there have been - I think there was an F, a VF, a VFDF, an FX.. maybe a SF.. Don't know if there's a .25AX yet or not.

Next time you solder a wire between wheels move it up half way so you don't make a lawn mower out of it. The less touching the ground to better

Engine # 1 bottom right .OS Max S bushing engine.
Engine # 2 Top OS25 SF .This is the previous model to the FX and the newer version of the FSR.Dual ball bearing .Good strong engine for R/C.
Engine #3 OS FSR .Dual ball bearing engine.Also a strong runner.