Zenoah G38

[cymaz]

Just got a G38 fitted with a magneto ignition, I believe. However I cannot seem to find any means of stopping it with a kill switch as there are no extra wires out of the magneto except the HT lead. Any ideas please as I want to fit a remote kill switch using my Tx. Thanks

[Rich too]

My 23 has the failsafe on the throttle, that should be sufficient (same as a glow engine) ? Rich

[stu knowles]

I always stop mine simply by closing the throttle. (Remove the idle adjusting screw) Isn't there a black wire, the end enclosed in some sort of bullet connector?? I always understood that putting that to earth would short the mag and kill the ignition but I haven't used it personally.

Lovely motor the z38, most compact and easy to start.

stu k

[cymaz]

Thanks Stu and Dickster, used the thottle cut and it worked a treat

[Former Member]

[This posting has been removed]

[Martin Harris - Moderator]

Even with a cut-off switch you should always treat a magneto equipped engine as live as any wiring disconnection or switch contact fault will potentially allow it to fail safe (live) - by design in the case of a full size engine in flight. There have been cases where pilots/engineers have suffered serious/fatal injuries through forgetting this. I once had to stop someone who should have known better standing below a Chipmunk prop and idly pulling it through compression!

[Ultymate]

On the magneto equipped Zenoahs as originally supplied there was indeed a black wire that when earthed out would kill the ignition. However back in the days of 35 Megs radio this black pigtail was noted as a prime source of radio interference and it used to be recommended to cut off the black wire. It may well be the case that this is what's happened to your engine in the past

[cymaz]

I will take note of all the posts. This will save missing fingers

As I don't have any black wire earth, would it be good practice to remove the plug cap when priming the engine and when not in use to reduce the accidental spark???

[Ultymate]

I would say not as to keep removing and replacing the plug cap will result in it being a slack fit. I wouldn't worry overmuch about "accidental" starts as the Magneto equipped enges have to be rotated /"flicked" hard to generate enough spark to start the engine

[cymaz]

Noted

[Martin Harris - Moderator]

I think that the Zenoah magneto turned over slowly during priming is unlikely to produce a spark, although I stand to be corrected on this but (as long as there's sufficient separation) your precaution shouldn't hurt. The Chipmunk, for instance, used an impulse mag for starting which stored rotational energy, releasing it at the appropriate moment, effectively giving a faster rotating mag to provide sufficient energy for the spark...when it didn't stick! Luckily, a trained ear could hear the lack of a loud clack when it stuck (not an unusual event) and a judicious thump with a blunt object would free things up!

Edit

(got interrupted by work and looks like Ulty got there much sooner,)

Edited By Martin Harris on 13/08/2013 15:00:40

[cymaz]

Converted the G38 with electronic ignition from J.E. and using the additional timing wheel with magnet attached. Also used Rxcel opto isolator . Perfect fit, perfect first time operation. Opto isolator excellent and safe.

Thoroughly recommended