This isn't a question, but just a comment to help someone who may be having this problem. I have and OS .40 LA and it ran well for me the first couple of times I fired it up. About the third time, all of a sudden the prop nut and spinner flew off as soon as I put the starter to it. I did it over and over again. Tightened the nut as hard as I could, with the same result. Come to find out I was choking the engine too much and it caused too much fuel in the cylinder, plus wetting the glow plug and causing so much pressure in the engine, that it would not turn over, causing the prop to spin off. Hadn't ever heard of this happening, but maybe it's just a rookie mistake. Just my $.02.

also make sure you reem the prop to the correct crankshaft size. all props have intentionaly small holes soas to be ready to reem.
d

Put gloves on and grab the prop in one hand and a cresent wrench in the other and give it 2 grunts LOL and it wont come off.

Be careful starting an engine that may be flooded. The situation is called hydrolock and the engine won't turn over since the liquid filling the cylinder is much less compressable than air (or air/fuel mix). In addition to spinning the prop off, you run a significant rick of bending or breaking the crank. After choking the engine and priming, always turn the engine over by hand once or twice to make sure it isn't hydrolocked before spinning the prop with a starter. If it is hydrolocked, remove the glow plug, invert the plane and turn the engine over several times to expel excess fuel.

Ross

I hate when my Nuts fly off. when I was first learning to fly I would always forget to pull the pressure line off the Muffler when I was refueling and of course filled the muffler up with fuel which in turn filled the engine causing the dreaded hydro lock. I did learn the hard way to hold a paper towel over the glow plug hole while you are turning the engine over to clear the fuel. (I always did it upright) Glo fuel tastes pretty bad and the taste stays around for a while no matter what you do.

Lookinup,I won't say how or why,but I second how glow fuel taste in the mouth hangs around for awhile.

Hey Lookinup,

I would hate it for sure if my NUTS flew off. It would be like changing from a rooster to a hen. Sorry, I just couldn't resist. Happy flying all.

Jeff

You may be running the engine too lean. Try richening up the mixture a little.

Liquid does not compress at all, But I mainly wanted to comment on something else...

First, don't have the glow plug igniter connected when you turn by hand.

Second, you don't need to remove the plug. Just turn the plane so the engine is sitting with the muffler down and turn the prop backward, any excess fuel will run out of the muffler port. (in the case of a 4-stroke, just turning backward should clear the fuel back into the carb).

MinnFlyer

Liquids ARE compressable, but not to any noticeable extent under ordinary pressures.

The cylinder would not likely be 100% full of fuel - the piston wouldn't move at all. Most probably, it would have both liquid fuel and air.

Good point on making sure that the glow plug is disconnected before turning over by hand! Although it is unlikely to kick too hard if you have a firm grip on the prop, why take a chance - REMOVE THE GLOW IGNITOR.

Regarding the removal of the plug vs letting the fuel run out the muffler, I have found that it is often difficult to get all of the fuel out this way. Although I have done it both ways, I have better luck removing the plug, draining the cylinder by inverting and flipping the prop and then giving it a spin with the starter. BE CAREFUL - fuel will spray out of the glow plug hole when you hit it with the starter.

I guess the message is the same; make sure that the engine is not hydrolocked before you start the engine. It is particularly important if you are using an electric starter instead of a chicken stick - very easy to ruin a good engine.

Ross