wtsidney

Got my hands on a used Four Stroke 91 Surpass 1 and Full Throttle is not maximum power or rpm.

Starting from Full Throttle maximum power / RPM increases as the carb is closed up to approx 7/8 of full (just a bit of the barrel restricted).

The engine starts easily and has nice smooth idle. Tried adjusting the needle valve a 1/2 turn in and a 1/2 turn out.

This is my first four stroke (FS) and while I have some experience and success with two strokes engines, this FS Sounds and Feels different - but I'm looking forward to it. Any ideas or suggestions?

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The engine is mounted on it's side with muffler tap into the fuel tank spinning a 14X10-6 zinger wood prop using 15% nitro with 18% castor synth blend

Bax

My Feedback: (11)

First off, the propeller you're using it too much for the engine. We'll use a 12 x 10 APC prop, or 13 x 8. The multi-pitch prop you have puts more load on the engine, and holds down the RPM.

Open the high-speed needle about 2-1/2 to 3 turns out, start the engine and get it to full. Then adjust the high-speed needle. Once it's adjusted to just rich of peak RPM, you can retard the throttle to adjust the idle mixture.

Use 5%-15% nitro fuel and an O.S. Type F glow plug.

wtsidney

Thank You for the prompt response will try a smaller prop.

Hadn't expected the prop to be to much. It falls within the prop selection for scale models.

Do you reccommend multi-pitch props? Sounded like a good idea when I picked it up.