El miércoles, 22 de julio de 2020, 0:36:05 (UTC-3), danlj escribió:
I've owned a Ventus CM for 20 years, have taken the engine from 17 hours to 67 hours and the airframe to 1200 hours without any starting difficulties. I have nothing to add to the preceding comments, and have no debate with them. I only wish to add my own experience.
As someone once said, all an engine needs is air, fuel, and spark -- in the right amounts. Here are some of the things I've learned:
1: Having the spark plug gapped correctly is critical to reliability -- 0..5mm -- I have used platinum plugs with complete satisfaction.
2: Having a charged battery -- 12.8 volts or more seems optimal.
3: Obvious but essential:
Fuel valve OPEN
Boost pump ON
Proper carburetor prime: too little and the engine won't start; too much and the plugs flood, and must be removed and cleaned because they're at the bottom of the cylinders. When the engine is cold, especially in cool weather, in my ship 4 full squeezes of the priming bulb is the minimum. If the engine doesn't start promptly, an extra squeeze or two while it's cranking may help.
In-air starts require less prime, probably because the engine retains some warmth in the engine bay.
4: As hinted by this thread, and taught to me, the #1 cause of electrical malfunction is *corroded contacts*. It is possible to check the resistance across contacts -- or simply disconnect, freshen the metal, reconnect, and spray with anticorrosion lube.
5: In-air shutdown: The manual says to let the engine cool at idle before stopping and stowing it. Years ago, I spoke to the engine designer, Wolfgang Emmerich, about this. He was *adamant* that this not be done. "I owned one of those gliders; I don't know why manufacturers give this advice. If you do not shut it down at full throttle, the carbs are over-pressured and they begin to leak."
I'd had some leakage at that point; I've ever since shut down at full power, and the leakage has never worsened, just a couple of drops.
6: I forgot to mention: both the starter button and the radio microphone button are on the stick. If one doesn't look, it is possible to be pressing the microphone button on final to the off-field landing. This has been done by at least two pilots, to my knowledge. The engine only starts if the started button is pressed... ;-)

Thank you Danlj.
Throughout these last three years that I own my ship, I´ve learned a lot about this engine...I had plugs flooded sometimes also. I heard before about stopping the engine at full power, but never with that conviction.
After stopping it did you used to wait to cool for a while or you stowed it directly?

I also heard about pressing the wrong button to start the engine!! but mine has the PTT button not at the top of the stick but in its front, so, no mistake there.

I would like to ask you a question also. These mikuni BN 38 carburators has needle valve seat (pop off) sized 2.0. There are pop off of 1.5 and 2.5 also. The standard carburator parts drawing indicates 1.5 for Mikuni BN 38, do you remember what is the indicated one for this engine? Anyway, mine with 2.0 works ok, but I still have this doubt.
Regards.