Starter cranks, then spins

[alexiskai]

Hi folks,

When I'm doing a cold start, I press the starter pedal and the starter starts to crank the engine. I pull the choke and hold it a second or two, and often what happens is that the engine putt-putts once or twice, then stops cranking and I hear a hum, like the starter has disengaged and is just spinning around, until I let off the starter pedal. If I repeat the sequence 1-2 times, it starts up. With a warm start this rarely occurs. The hum only happens once the engine has caught on its own. If the engine is not catching (say for example I've forgotten to turn the key) then the starter will continue to crank the engine.

Does anyone know (1) what this hum is indicating, (2) whether it's a problem, and (3) whether there's anything I can do to improve my cold starts. I'm sure this has been asked before but I'm not sure which search keywords I should be using to find the answer.

Thank you

[Gary WA]

Grounding?

[Terry, NJ]

You are correct! The engine, when it fires, kicks the bendix out of engagement with the flywheel (As it's supposed to) and the starter, no longer engaged to the engine, whirrs along. This is nothing, It's just doing what starters do. Take your foot of the starter and start again. But the real problem is why doesn't the engine keep running once it's started? Try engaging the hand throttle just a crack. One thing that has wored for me is to advance it 1-2 degrees. Absolutely no more than that! Most people will tell you not to advance it at all and they're right.Sometimes it helps. If not, discontinue! One thing that may help is an auxillarly ground cable to the engine. This brought my cranking speed up noticably.
Terry

[1931 flamingo]

Starter switch is sticking......
Paul in CT

[WHN]

Originally Posted by Terry, NJ

You are correct! The engine, when it fires, kicks the bendix out of engagement with the flywheel (As it's supposed to) and the starter, no longer engaged to the engine, whirrs along. This is nothing, It's just doing what starters do. Take your foot of the starter and start again. But the real problem is why doesn't the engine keep running once it's started? Try engaging the hand throttle just a crack. One thing that has wored for me is to advance it 1-2 degrees. Absolutely no more than that! Most people will tell you not to advance it at all and they're right.Sometimes it helps. If not, discontinue! One thing that may help is an auxillarly ground cable to the engine. This brought my cranking speed up noticably.
Terry

On a cold start I have always advanced the hand throttle two positions. Try it, I’ve been doing it for 60 years. Enjoy.

[GRutter]

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As 1931 Flamingo stated, the starter switch may be hanging and the humming you hear may be the starter motor running.
But if that were the case, then the bendix (if operating correctly) would be trying to engage with the ring gear... and you would definitely hear more than humming.
In my opinion, the bendix may not be disengaging from the engine and the humming may be the engine spinning the starter. Your starter will not last long.
I would pull the starter and inspect the bendix. Check the spring, bolts etc.

[SSsssteamer]

With cold starting, I find by opening my GAV valve a quarter of a turn counter clockwise and using the choke, my A will then start right up and keep running. With The GAV valve closed, the engine may not start at all. The engine needs the richer fuel mixture from the GAV valve to keep on running. After the engine has warmed a bit, for leaner running, then the GAV valve can then be adjusted closer to closed (clockwise). I hope that this helps.

[katy]

Originally Posted by Terry, NJ

You are correct! The engine, when it fires, kicks the bendix out of engagement with the flywheel (As it's supposed to) and the starter, no longer engaged to the engine, whirrs along. This is nothing, It's just doing what starters do. Take your foot of the starter and start again. But the real problem is why doesn't the engine keep running once it's started? Try engaging the hand throttle just a crack. One thing that has wored for me is to advance it 1-2 degrees. Absolutely no more than that! Most people will tell you not to advance it at all and they're right.Sometimes it helps. If not, discontinue! One thing that may help is an auxillarly ground cable to the engine. This brought my cranking speed up noticably.
Terry

Ditto

[alexiskai]

Thanks for the feedback everyone. I'd forgotten about the GAV setting, I'll experiment with that for awhile and see if it improves my cold starts.

[Benson]

One or two seconds of choke is all that is needed. holding choke will flood engine.

THE GENERAL RULE on cold starts is if engine starts and dies right away you are too lean...

A factory setup carb will run at about 1/4 turn at sea level some need more...

Increase GAV 1/2 turn and retry. if stalls try another 1/4 or 1/2

If very cold some need 1 1/2 to keep running. Reduce as it warms up.

Carbs are different some need more or less to keep running.

BLACK SMOKE AND sputtering? ... reduce ie clockwise.

[Big hammer]

Turn the gav richer, pull the choke, with the key on THEN hit the starter, release the choke after a couple of turns or when the fires.