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Author Topic: Blue Hit & Miss Ground?  (Read 329 times)

Rapmoz

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Blue Hit & Miss Ground?
« on: November 24, 2019, 03:14:52 am »
 Hi, I just test run a H & M engine, probably the first model.

It's new, never used. After filling the tank (Coleman fuel + 4% 2 stroke oil) the engine starts second flick. It turns perfectly but I observe a superb spark of 8mm between the Hall sensor and the magnet (not very safe with gasoline vapors!), I did not observe this on YT videos of chinese H & M.
Then, of course, the engine stops after 30 seconds, no more spark, the sensor is blown …

I think the problem is maybe related to the grounding of the motor.
 for my airplane models, I use a RCEXL ignition module, this module is grounded to the engine but this orange anodized module has not grounding wire to connect ...
Thanks for your remarks and your help, Chris

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rodnoc

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Re: Blue Hit & Miss Ground?
« Reply #1 on: November 24, 2019, 02:18:34 pm »
The engine needs to be grounded to the negative of the battery.
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RedRyder

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Re: Blue Hit & Miss Ground?
« Reply #2 on: November 24, 2019, 03:14:45 pm »
Correct.... if you don't ground the engine to the battery/ignition box, you will very quickly fry your hall effect sensor. Sometimes even just 2 revolutions is enough to fry it.
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Rapmoz

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Re: Blue Hit & Miss Ground?
« Reply #3 on: November 25, 2019, 10:40:55 am »
Hello RedRyder and Rodnoc,
Many thanks for your replies and help, I finally plugged an old Pegasus CDI module from a severly crashed plane and it turns well but needs much more tunings.
I've never seen before an engine with a so sensitive carb needle  , it is a bit loose in the threads of the carb so the engine is flooded when the needle is open more than 1/10 of a turn from the closed position.
Is it the same thing for yours H&M's?
Also have you a source to buy another Hall sensor mounted on a little green board? I've been unable to find another one on the net, have no spare and very afraid to fry this one!
Many thanks, Chris.
Below, the not-very-academic system to test run the engine!
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rodnoc

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Re: Blue Hit & Miss Ground?
« Reply #4 on: November 25, 2019, 02:11:37 pm »
An oversize needle orifice or blunt needle taper would interfere with fine adjustment and act more like an on/off valve.  The coarse needle threads don’t help, either.

The carb/mixer on my engine will allow it to run within about 120* of needle twist with 35:1 Coleman's and Seafoam.

You can get a complete ignition system with spare plug from Banggood for $40 and postage.
https://tinyurl.com/tyazy9z
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