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General Category => General Discussion => Topic started by: SED on July 18, 2016, 01:21:02 PM
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Hoping Chuck or another of the A & P guys on here can answer this for me.
Do magneto ignitions ever run resistor plug caps to suppress radio frequency noise?
Do aircraft ever run inductive tachometers with a magneto? If so, how do they suppress the RF noise?
Thanks,
Shawn
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^^^^^^
Wat Mike sez. Woo Hoo!! Finally have my computer back on line. :smiley:
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+1 re: ignition leads.
Some cwetificated engines use a 3-phaae tach generator feeding
a synchronous indicator; may be unshielded, but is low voltage.
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Thank you guys!
The reason I ask is because I'd like to install a tach on a magneto ignition motorcycle (Ariel). It would be much cheaper and less work to install a magnetic tach, but the only manufacturer that claims it can be done is Smiths http://smithsgaugesusa.com/ and they want a resistor plug cap. The web is full of statements that your hair will fall out if you install resistor anything on a magneto ignition so I thought I'd check with the guys that rely on magnetos the most - small aircraft pilots and mechanics.
Thanks,
Shawn
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I would think the problem with a magneto is getting access to the points, perhaps use a sensor that clips arount the plug lead like you see on some timing lights.
Talk to Speedhut, they may have an easy solution, they say it "will work with any ignition"
http://www.speedhut.com/faq.i#what-do-i-need-to-connect-my-tachometer-to
What model Ariel?
I would think the 6V electrics might be more of a problem.
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The bike is VH 500 single. The bike has 12volt lighting but I would pull the generator and battery for the track so voltage wouldn't matter. Smiths uses a remote battery to run their unit, but Speedhut doesn't have that. Speedhut's literature assumes some form of coil ignition - no reference to magnetos in the tech files. There are photos of Ariels modified with mag drives running cable tachs, but I don't know how it's done. Starting to look to be the simplest way though.
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Nice, I should have seen it in your signature.
I had an old VB and a 500 twin, I forget the model No
The mag sprocket turns at half engine speed, if you mounted a strong magnet on the sprocket so it was close to the cover you might be able to pick up a reed switch on the outside, no need to drill holes in the case.
It would be fairly easy to try out the concept anyway.
(http://i1304.photobucket.com/albums/s526/Kiwi_Roy/Misc%20Pics/Tacho20Pickup_zpshnyvnsuu.jpg)
If the pickup works it could be adapted to any electronic tacho, 1 pulse per engine revolution.
Oopps, I should have said non ferrous bracket, Aluminum or brass, copper are fine.
BTW are the old plunger oil pumps still operating, still have a dry sump lube system?
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I run a Westach directly off the "P" lead on Mouser. It needs a small fuse in case the tach grounds out.. that would shut off the ignition. :shocked: You can also use an inductive pickup on a non shielded plug wire.
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Here's a magneto to tach converter..
https://www.amazon.com/Auto-Meter-9117-Tachometer-Adapter/dp/B00063068W/ref=sr_1_11?ie=UTF8&qid=1468969757&sr=8-11&keywords=magneto+tachometer
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Nice, I should have seen it in your signature.
I had an old VB and a 500 twin, I forget the model No
The mag sprocket turns at half engine speed, if you mounted a strong magnet on the sprocket so it was close to the cover you might be able to pick up a reed switch on the outside, no need to drill holes in the case.
It would be fairly easy to try out the concept anyway.
(http://i1304.photobucket.com/albums/s526/Kiwi_Roy/Misc%20Pics/Tacho20Pickup_zpshnyvnsuu.jpg)
If the pickup works it could be adapted to any electronic tacho, 1 pulse per engine revolution.
Oopps, I should have said non ferrous bracket, Aluminum or brass, copper are fine.
BTW are the old plunger oil pumps still operating, still have a dry sump lube system?
That's the Ariel timing cover! It would be a simple setup, but wouldn't the radio interference cause problems pickup (Reed switch?) or with the wires to the gauge?
I've replaced the plunger pump with a Morgo Rotary pump, but it blocks the end of the cam too.
VBs and KH twins, especially the early ones, are cool bikes.
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I run a Westach directly off the "P" lead on Mouser. It needs a small fuse in case the tach grounds out.. that would shut off the ignition. :shocked: You can also use an inductive pickup on a non shielded plug wire.
Looked up Westberg Westach. They do some interesting things - instructions to mount to a Ducati for example. I should call them.
Is the "P" lead the points lead? The silly Lucas facecam mag has rotating points and all the connections are made internally so no easy way to pull a signal off the points that I can figure out.
As for the inductive pick-up, that's what was on a little digital tach, but revving the engine sent it into paroxysms of apoplexy. Smiths has an inductive pickup tach, but it requires the use of resistor sparkplug caps which apparently should not be used with magneto ignitions.
Chuck, enjoyed meeting you at John Day!
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Here's a magneto to tach converter..
https://www.amazon.com/Auto-Meter-9117-Tachometer-Adapter/dp/B00063068W/ref=sr_1_11?ie=UTF8&qid=1468969757&sr=8-11&keywords=magneto+tachometer
Thanks for the that Atavar, but AutoMeter also wants resistor plugwires:
https://www.autometer.com/media/2650-753X.pdf
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That's the Ariel timing cover! It would be a simple setup, but wouldn't the radio interference cause problems pickup (Reed switch?) or with the wires to the gauge?
I don't think so, there's not a lot of energy floating around the mag, besides the reed switch wires could be shielded if necessary.
I'll test it out over the weekend using a piece of 1/8" aluminum in place of the timing cover
I was at JD also with my Green V11 Sport at the back fence.
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I don't think so, there's not a lot of energy floating around the mag, besides the reed switch wires could be shielded if necessary.
I'll test it out over the weekend using a piece of 1/8" aluminum in place of the timing cover
I was at JD also with my Green V11 Sport at the back fence.
Roy!
You were riding with Stelvio Sean (?) over Washington pass. We followed you into the rest stop at the summit on my LMIII and Carlo was on a new white Cali 1400.
So you have Ariels in the lower mainland! (somehow I assumed you were living in NZ). We could get together for a little Arieling too.
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Oh, that was you, I often think we should have name badges with our handle on for the rallies.
No, I don't have any Ariels here, Corry who you must have met has several nice Velos.
The Red Hunter has always been my favorite.
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Oh, that was you, I often think we should have name badges with our handle on for the rallies.
No, I don't have any Ariels here, Corry who you must have met has several nice Velos.
The Red Hunter has always been my favorite.
Roy, didn't get to talk to you long enough at John Day, but want to thank you for all you've done for WG people. I have a file of your stuff on the computer to refer to.
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Looked up Westberg Westach. They do some interesting things - instructions to mount to a Ducati for example. I should call them.
Is the "P" lead the points lead? The silly Lucas facecam mag has rotating points and all the connections are made internally so no easy way to pull a signal off the points that I can figure out.
As for the inductive pick-up, that's what was on a little digital tach, but revving the engine sent it into paroxysms of apoplexy. Smiths has an inductive pickup tach, but it requires the use of resistor sparkplug caps which apparently should not be used with magneto ignitions.
Chuck, enjoyed meeting you at John Day!
Enjoyed meeting you, too.. :smiley:
On an aircraft magneto, the P lead is what is grounded to keep it from firing.
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You could always use an audio tach app on your phone.. :lipsrsealed:
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The sketch I posted earlier will work, I found the reed switch is easily activated through 1/8" aluminum up to 1" away by a small magnet
I ran it at 2700 RPM the equivalent of 5400 for the Ariel and got a nice square pulse.
http://s1304.photobucket.com/user/Kiwi_Roy/slideshow/Tach%20Pickup
This will work with any electronic tach. The reed switches are rated in Billions of operations and cost a few cents each.
I'm sure other sensors like the Hall Effect will work also but they are overkill
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The sketch I posted earlier will work, I found the reed switch is easily activated through 1/8" aluminum up to 1" away by a small magnet
I ran it at 2700 RPM the equivalent of 5400 for the Ariel and got a nice square pulse.
http://s1304.photobucket.com/user/Kiwi_Roy/slideshow/Tach%20Pickup
Wow, that is cool Roy! I might know what to do with that, or you might be overestimating my abilities!
It's a totally new option for those who want a modern tach.
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More than anyone needs to know, but full explanation
https://disciplesofflight.com/airplane-ignition-system/