Running engine without prop
08-17-2003 | 07:15 PM
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From: Holden, MA
Running engine without prop
Can I run my OS-FS-70-4-stroke without the prop for a short time ? Need to make a few adjustments and feel the blade will be in my way. Thanks, Carl.
08-17-2003 | 07:28 PM
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Running engine without prop
I think it best you follow the instructions that came with the engine . If they say remove propeller & adjust , do it . Something way back in my mind says it won't say it . This must be one of those mysteries of life my mother told me about ? MAX H.
08-17-2003 | 08:27 PM
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From: Castaic, CA
Running engine without prop
Running an engine without a prop (or load) is what is known as a shaft run. I've never seen it happen on a 4 stroke, but I doubt the valves would servive the experience and the piston might not either.
Maybe some others here have experienced it.
Maybe some others here have experienced it.
08-17-2003 | 10:45 PM
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From: Towson, MD
Running engine without prop
run it without a prop and you wil see some serious rpm, for about ten seconds. Ever hear of a red line? With no load on the engine it will turn as fast as it can until it breaks. Don't do it!
Max
Max
08-18-2003 | 01:07 AM
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From: Adelaide, South Australia
Running engine without prop
Well I'm baffled. Just what adjusments are you planning on making that can't be done from behind the prop? There are ways to have a deliberate shaft run that were used long ago to run in things like Dooling .61's but it's probably best not to mention them here or the field nazis will have a ball 
I wouldn't try a shaft run with a 4 stroke though because those valves will float like crazy and get bounced around by the piston.
I wouldn't try a shaft run with a 4 stroke though because those valves will float like crazy and get bounced around by the piston.
Bronzemaster:
08-18-2003 | 02:45 AM
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From: Los Angeles,
CA
Running engine without prop
There's no way you should run an engine with no load and no flywheel effect, especially not a 4 stroke.
With no load it's going to scream and destroy your valves, con rod and piston and with no flywheel effect, it's going to oscillate backwards and forwards breaking everything inside.
Have you ever seen / heard an engine where the prop broke off and it kept running? Not a pretty sight!
What are the adjustments you are planning to make anyway? Whatever they are, the conditions are so different with and without the prop that they will be useless.
Much better to do what everybody else does with the engine, and follow the manufacturer's recommendations.
-David C.
With no load it's going to scream and destroy your valves, con rod and piston and with no flywheel effect, it's going to oscillate backwards and forwards breaking everything inside.
Have you ever seen / heard an engine where the prop broke off and it kept running? Not a pretty sight!
What are the adjustments you are planning to make anyway? Whatever they are, the conditions are so different with and without the prop that they will be useless.
Much better to do what everybody else does with the engine, and follow the manufacturer's recommendations.
-David C.
