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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › Breaking starter shafts with ys120sr
06-04-2015 12:13 AM  4 years ago
Rob43

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Midland, MI USA

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I had not modded mine. It just let the set screws slip. I installed a less damaged one. I ground deeper larger pilots for set screws. It worked fine this evening. Ordered a new shaft, and will make flats on the new one,Rob
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06-12-2015 06:34 PM  4 years ago
ticedoff8

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Morgan Hill, CA. USA

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You already have the Dynatron.
I've been using an old Sullivan Hi-Torq starter for the last 10 years. On a 3S pack, it starts my YS 120SR-X with no problems.
I've used it with everything from OS 50 up to YS 120.

Occasionally, I'll hook a 2nd 2S LiPo in series (5S) if a motor is stiff.

The beauty of this starter is that it has a soft start to it - it is not a "instant on" 100% torque light switch. It will turn the motor and hit the compression stroke, then build torque until the engine moves past TDC. Then, it starts turning continuously and fast.

I doubt this is by design. I think it is because it is old.
It has never twisted the hex adapter off the starter shaft or broken and shaft or OWB.

And, am still using the same $9 starter shaft extension I bought 8 years ago.
I bought one of those $100 Sullivan starter shaft extensions and the chrome plate stripped off inside of the housing. It lasted 3 starting attempts now it just free-spins. POC.

At the last flight of the day, I'll run the engine dry - fly it until the engine quits.
On the first flight of the day, I will "prime" then engine by spinning the motor and cycle the throttle form 0 to 100% two or three times.
Then, hook up the glow ignitor and spin the engine.
It usually catches within 2 or 3 seconds.
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06-14-2015 06:35 AM  4 years ago
Aaron29

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USA

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I am not a fan of loosening the glo plug to start, then retighten.
Too bad, as this is really your solution.

I had a 91 that was difficult to turn over with a standard starter. A little less than a turn out on the plug, and it'd crank up.

And that was on a 91. A 120 has a lot more guts.

Now, if I threw a drill at it, it'd probably work, but then you are just powering through any resistance. And you'll bust whatever gets in the way.

Enough balls on your starter and you'll kill a rod if any hydrolock is present. Tread lightly.

Might consider a more standard starter or the loosen method, or both. This isn't a Cummins you're starting. Heh.
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06-14-2015 02:18 PM  4 years ago
Rob43

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Midland, MI USA

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I am not familiar with the tip of loosening the plug...I can see how this would clear a flooding condition, but are you suggesting that you loosen it just enough to get the engine to start, and then tighten it while it's idling?

Interesting. Learn something every day. I've always just taken out the plug to clear the engine.
Rob
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06-14-2015 04:47 PM  4 years ago
Aaron29

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USA

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Yes. It lowers the compression and helps a lot. But this isn't a flooding thing. This is getting enough relief to allow start. For flooding, you still remove the plug and blast out the fuel.

This is for when your starter is having a hard time turning the engine over. But it also helps relieve stress on starters and shafts if that is an issue, which it appears to be, given the OP predicament.

If you've ever had an old motorcycle with kickstart, the larger singles had a "Deco" lever. Decompression. It basically did the same thing with a valve. You opened the valve to kickstart then closed it to ride. Otherwise you'd have to be Michael Moore to get the thing to turn over. As a man of relatively small stature I can tell you I could stand on the kickstarter without the Deco on. Stomp and stomp and it wouldn't move. LOL

Obviously you don't loosen the plug much unless you want to make an air rifle out of your plug hole. And don't forget to retighten it!

It's amazing and it doesn't affect the idling too much. But if you fly it, I guarantee you'd lose the plug.

To the OP: as an analogy of why I think you should do this. With that motorcycle, without deco I stomped and stomped and it would hurt my leg and foot. Same thing is happening to your start shaft. All that force. Lower that compression and your parts will thank you!
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06-19-2015 11:29 PM  4 years ago
ticedoff8

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Morgan Hill, CA. USA

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The "loosening of the glow plug" is okay for starting as long as you have easy access to the plug and you are using high nitro fuel.

Even then, it is a little iffy getting it tightened down correctly.

The symptom of a worn out motor is that it won't start and the "remedy" for starting a worn out motor is to use high nitro fuel.

A lot of plankers use this technique to avoid the "kick back" that happens when the fuel ignites before TDC (high nitro does that) in ahigh compression motor.
And the kick back really raps your knuckles.

If the engine is not flooded and the starter is strong enough to get it over the 1st Top Dead Center compression, then usually it will start spinning it faster.

It is the jack-hammering of the electric drill or the Align starter that causes the hex-head to strip or the starter shaft to break.

On my motors, for some reason, the Rotor Rage coagulates and makes it hard to turn over the first start of the day.
Once some fresh fuel gets into the head / bearings it spins much easier.
+ > ÷
Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!
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06-19-2015 11:40 PM  4 years ago
Rob43

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Midland, MI USA

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Simply making better spots for the set screws on my starter shaft seemed to help.Rob
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HomeRC & Power✈️Aircraft🚁HelicopterEngines Plugs Mufflers Fuel › Breaking starter shafts with ys120sr
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