[axman88]

I saw a U-tube video, where a moto rider was demonstrating how to make "awesome backfires" by using the kill switch.  He was cruising in low gear in a parking garage, used the kill switch to interrupt the ignition, then switched back on while still rolling to produce a satisfyingly loud blast that echoed through the structure.

This seems like a bad idea to me.  Am I getting old?  Is this "a thing"?

[gizzo]

I saw a U-tube video, where a moto rider was demonstrating how to make "awesome backfires" by using the kill switch.  He was cruising in low gear in a parking garage, used the kill switch to interrupt the ignition, then switched back on while still rolling to produce a satisfyingly loud blast that echoed through the structure.

This seems like a bad idea to me.  Am I getting old?  Is this "a thing"?

AKA "Key Bangers". Too much fun.

[Bilgemaster]

I saw a U-tube video, where a moto rider was demonstrating how to make "awesome backfires" by using the kill switch.  He was cruising in low gear in a parking garage, used the kill switch to interrupt the ignition, then switched back on while still rolling to produce a satisfyingly loud blast that echoed through the structure.

This seems like a bad idea to me.  Am I getting old?  Is this "a thing"?

I've seen (and heard) firsthand what I was led to understand was an old street-rodders' show-off trick of fitting a sparkplug into the muffler's exiting exhaust pipe, whereby one kills the ignition briefly, restarts, and a fair helping of unburnt fuel would erupt in an huge earsplitting tongue of flame. Stupid? Sure. The fact that this was done with an amphibious Amphicar ON THE WATER seemed doubly so.

[olhogrider]

How about the engines that used a piece of metal on top of the spark plug that you would push down against the engine fins to short out the plug and stop the engine?     It was a simpler time back then.   

That's because a magneto is always hot unless it is shorted out.

[Richard230]

That's because a magneto is always hot unless it is shorted out.

And headlight brightness varied with the speed of the engine - from a dim glow at idle to: "can you see me now?" when the engine was in its power band.   

[twocoolgliders]

Off topic, but perhaps interesting to gear heads:


In the world of airplanes, most have magneto ignition.  Also most turn off the engine by moving the (pilot cockpit controlled) mixture control to full lean...

Two problems with this method.....one...it is easy to forget to turn off the mag switch (usually key switch)  and you then kill the battery...


or you have a break in the magneto ground wire...so the mags are "hot" even though the switch is "off"...all it takes is a push on the propeller and the engine can start!  And yes it does happen from time to time.

I hate it when people come over to an airplane and they just feel the need to hang their hand on the propeller.  It is a "loaded gun"

My planes have all been "antiques" with 1930's vintage engines....no mixture control on the carburetor...so I always shut off with the mag switch...Does two things...stops the engine (by grounding out the magnetos) ...and proves the ground wires are still intact.


Cookie

That's because a magneto is always hot unless it is shorted out.

[olhogrider]

Off topic, but perhaps interesting to gear heads:


In the world of airplanes, most have magneto ignition.  Also most turn off the engine by moving the (pilot cockpit controlled) mixture control to full lean...

Two problems with this method.....one...it is easy to forget to turn off the mag switch (usually key switch)  and you then kill the battery...


or you have a break in the magneto ground wire...so the mags are "hot" even though the switch is "off"...all it takes is a push on the propeller and the engine can start!  And yes it does happen from time to time.

I hate it when people come over to an airplane and they just feel the need to hang their hand on the propeller.  It is a "loaded gun"

My planes have all been "antiques" with 1930's vintage engines....no mixture control on the carburetor...so I always shut off with the mag switch...Does two things...stops the engine (by grounding out the magnetos) ...and proves the ground wires are still intact.


Cookie

Close. The hot mag switch has no effect on the battery. That would be the battery switch. Chopping the mixture ensures that there's no fuel in the cylinders when your friend pulls on the prop. Without a mixture control you must get worse fuel economy and less performance! What a deal. I must say, I was shocked when the consensus of plane manufacturers decided that it was best to run on the lean side of ideal. Lean to max EGT, then lean a little more.

[twocoolgliders]

Right...sort of ...with a key switch....the mags and the electrics are on the same switch, (most planes)  when you have it on "both"...both mags are ungrounded...and the electrical system is "on" ....that is stuff like avionics, lights etc.  There is also current to the alternator and coil.   So if you shut off with mixture...you still must turn the key to "off" position or you will return to a dead battery


In antique planes like mine....there is no electrical system...no alternator, no generator, no starter, no lights,,
nothing...just magnetos......the mag switch has left, right, both, and off.  And you want the engine ready for a hand prop, so you don't want to run the cylinders dry of fuel...of course just a few pull-throughs of the prop will charge the cylinders if needed.

With airplanes, if you are worried about fuel economy, you have the wrong hobby!

Again with my antiques it give maybe 15 miles per gallon.  (4 gallons per hour at 60 miles per hour) if no wind.. If you don't fly too high...leaning mixture is not necessary.  Low and slow is more fun anyway.  You can adjust the mixture at the carb if you are always at high alt...


Cookie

Close. The hot mag switch has no effect on the battery. That would be the battery switch. Chopping the mixture ensures that there's no fuel in the cylinders when your friend pulls on the prop. Without a mixture control you must get worse fuel economy and less performance! What a deal. I must say, I was shocked when the consensus of plane manufacturers decided that it was best to run on the lean side of ideal. Lean to max EGT, then lean a little more.

[olhogrider]

Right...sort of ...with a key switch....the mags and the electrics are on the same switch, (most planes)  when you have it on "both"...both mags are ungrounded...and the electrical system is "on" ....that is stuff like avionics, lights etc.  There is also current to the alternator and coil.   So if you shut off with mixture...you still must turn the key to "off" position or you will return to a dead battery


In antique planes like mine....there is no electrical system...no alternator, no generator, no starter, no lights,,
nothing...just magnetos......the mag switch has left, right, both, and off.  And you want the engine ready for a hand prop, so you don't want to run the cylinders dry of fuel...of course just a few pull-throughs of the prop will charge the cylinders if needed.

With airplanes, if you are worried about fuel economy, you have the wrong hobby!

Again with my antiques it give maybe 15 miles per gallon.  (4 gallons per hour at 60 miles per hour) if no wind.. If you don't fly too high...leaning mixture is not necessary.  Low and slow is more fun anyway.  You can adjust the mixture at the carb if you are always at high alt...


Cookie

It has been decades since I flew an antique, a Stearman and a DC-3 but in my 47 years of flying (ATP) and working on them(A&P), every plane with a battery has had a battery master. That is completely unrelated to the magnetos. Otherwise a dead battery would cause an engine failure or a mag failure would cause all your electrics to fail. Neither one of those happen. This may not be the case in a Sopwith Camel or some crazy homebuilt or ultralight but pretty sure it is true of any plane built in a factory in the last 100 years. If you can give me an example of your "key operates the electrical system" I would love to know what kind of plane that is.

[GlennF]

There is just nothing like seeing someone starting a radial that has sat for a while  ...

https://www.youtube.com/watch?v=EkcX0KGIBwk

[olhogrider]

There is just nothing like seeing someone starting a radial that has sat for a while  ...

https://www.youtube.com/watch?v=EkcX0KGIBwk

Love the commentary  My last job was flying an Airbus. Starting was literally pushing a button. Nothing else. The only time you touch the throttles (thrust levers) is on takeoff, then at the 1000' then again in the landing flare.

[gizzo]

With airplanes, if you are worried about fuel economy, you have the wrong hobby!

Again with my antiques it give maybe 15 miles per gallon.  (4 gallons per hour at 60 miles per hour)

About the same as my antique ski boat then (SBC power).  . Maybe a bit more economical.

My aircraft uses no fuel. Just a quick run off a steep slope... Terribly slow way to travel,  though.

Oh,  and I always turn my bike off with the key and put my left glove on first.

[Sprinter]

Not sure this helps but this is what the book says......

ENGINE KILL SWITCH
Engine "OFF" Engine "ON"
CAUTION
Turn off ignition switch when engine is not running. Failure to do so will discharge the battery due to the headlamp
being continuously "ON".

I always turn off at the switch, never had a problem but next time I do I will check to see if headlamp still on!

[twocoolgliders]

https://www.google.com/imgres?imgurl=https%3A%2F%2Fwww.desktopaviator.com%2FProducts%2FPanel%2FModel_1010%2Fimages%2Fimg0001.png&imgrefurl=https%3A%2F%2Fwww.desktopaviator.com%2FProducts%2FPanel%2FModel_1010%2Findex.htm&docid=A4efmXypF4j2PM&tbnid=XyjbnptfC8cVLM%3A&vet=10ahUKEwir443esaPmAhWod98KHYqUDH8QMwjpASgcMBw..i&w=573&h=334&client=firefox-b-1&bih=905&biw=1280&q=cessna%20master%20switch&ved=0ahUKEwir443esaPmAhWod98KHYqUDH8QMwjpASgcMBw&iact=mrc&uact=8

Oh  I get what you are talking about now...like the typical Cessna panel shown in photo above.   

But again if you turn off engine with mixture, or with key...it is possible to leave electrics "on" (alt/ batt) and get a dead battery if you forget.


Cookie
 

[twocoolgliders]

way off topic and probably useless information for RE...but what the heck!


https://www.google.com/search?q=magneto+switch&client=firefox-b-1&source=lnms&tbm=isch&sa=X&ved=2ahUKEwi4q4iotqPmAhViRN8KHeuQDC0Q_AUoAnoECA4QBA&biw=1280&bih=905

above is the switch which I am used to...typical of 1940's vintage planes which have no electrical system.

https://www.google.com/imgres?imgurl=http%3A%2F%2Fwww.2040-parts.com%2F_content%2Fitems%2Fimages%2F72%2F2004372%2F001.jpg&imgrefurl=http%3A%2F%2Fwww.2040-parts.com%2Faircraft-magneto-switch-a-c-type-a-9-off-bat-l-r-and-both-i2004372%2F&docid=mwWhpST2j7CQ5M&tbnid=r9ZfDVvkQL7qgM%3A&vet=10ahUKEwjBhaiqtqPmAhUqmeAKHTf-BccQMwhYKAowCg..i&w=500&h=375&client=firefox-b-1&bih=905&biw=1280&q=magneto%20switch&ved=0ahUKEwjBhaiqtqPmAhUqmeAKHTf-BccQMwhYKAowCg&iact=mrc&uact=8


The image above is one which combines "battery" along with right and left and both mag  all on one switch.  Typical of older planes which do have an electrical system (battery).

https://www.google.com/imgres?imgurl=https%3A%2F%2Fi.pinimg.com%2Foriginals%2F0c%2F77%2F3c%2F0c773c1b2dea1a6630eb26e85af315ce.jpg&imgrefurl=https%3A%2F%2Fwww.pinterest.dk%2Fpin%2F315885361340255404%2F&docid=5orW5nYpVEUTAM&tbnid=cwaFS731s4b5PM%3A&vet=10ahUKEwikqdXbt6PmAhXCMd8KHYGWA_YQMwjEASgOMA4..i&w=400&h=300&itg=1&client=firefox-b-1&bih=905&biw=1280&q=magneto%20switch%20toggle&ved=0ahUKEwikqdXbt6PmAhXCMd8KHYGWA_YQMwjEASgOMA4&iact=mrc&uact=8

Above...some old planes have simple toggle switch for each mag