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New OS 75 AX

Old 09-08-2007, 04:04 AM
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Default New OS 75 AX

recement, I bought a OS 75 AX and I cannot reach more than 9500 with a propeller APC 14X6 recommended like the smallest propeller usable for this engine

I use 15% blend fuel
I have make a flight with my plane SHOWTIME 50 of 6.5 pounds and I felt that the engine was very weak for a plane 3D of this size

what you recommends to me?
Old 09-08-2007, 03:28 PM
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Default RE: New OS 75 AX

Have you broken in in the motor, I would use a 10% nitro fuel and add a few ounces 2-3 of castor oil "made for model fuel" to a 18% caster oil fuel. when running the engine adjust the needle for a extra rich setting where there's good white smoke but not rich enough that it quits. Ringed engines take longer to break in ABC engines are quicker. If you break the engine in flying don't run on full throttle for too long before cutting down the idle.

I have broken all my engines in like this and they have run great with alot of power. The 4-strokes and 2-stroke ringged engines I have took a few gallons to get run in right. The ABC engines I have took around 1/2 gallon to get running powerfull.
Old 09-10-2007, 10:18 AM
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Default RE: New OS 75 AX

To get more RPM, you will have to go to a smaller propeller. O.S. makes the propeller recommendations that they do because they have to consider the strict noise limitations in Japan. If you run a 12 x 8 propeller, you'll see a RPM increase, and likely get the performance you're looking for.
Old 09-17-2007, 09:14 PM
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Default RE: New OS 75 AX

I'm using a MA 14x8 and pull a nice 8800+ on the ground w/ 15% Nitro. Was a bit over 9K with a MA 14x6 - but a bit louder (95dB) as opposed the 14x8 with 89dB - using stock muffler.

Mine doesn't like to start cold, but one flip after a flight will have it off and running!

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