I'm thinking analog also, the digital is too sensitive. You would get one fairly cheap for what you need.

 

Same experience, analogue works

 

That's right, you get stray high frequency high voltage from the ignition wires all through the low voltage wiring. I put a scope on it once and was pretty surprised. An analog meter effectively is a low-pass filter, it won't react to high frequency stuff. You should see what my Yamaha DT-2's AC magneto output looks like. It's way dirtier than you would expect.

 

Hi NewbornLobster, I have great interest in this subject. Exactly what brand & model meter are you using? I'm trying to figure out which meters work & which don't.

Would be helpful if members would say what meter they use that works & what meter doesn't work. I mean digital meters.

One in USA for sure goes crazy is Harbor Freight Cen-Tech. $6.49 or sometimes free on give a way promotion. We used these at work all the time when there was risk frying the meter. Never used it on sensitive computer circuits. I had maybe 6 or 8 of them on free give away. Over time smoked them all. It worked fine with motor stopped & ohm meter. Amp meter worked good, but not very much amps.

My other meter is Extech MA200. About $80.00 from Fry's electronics. They don't sell it anymore. Mainly made for AC house wiring etc, but works perfectly for Triumphs running or stopped. I've even zip tied it to bars for extended road test to observe actual voltage during all day ride, city & country.

I've used various models of Fluke meters. All worked motor stopped & running. All these were in the $200-500 dollar range. Not needed for old Triumphs, but they are very nice. Fuses can cost $20+.

All analog meters work fine, but harder to read accurately. I have old Radio Shack analog multi meter. Kind of hard to read on 20v scale. When you are testing Zener diode you want to see volts very closely. Separate ammeter is needed for Zener test that is also accurate.

I really don't know exactly why some digital work, others don't. I don't know what price point becomes the ones that work?? Or is price not a factor??

This is why I want to know what meters work or not. So owners can test voltage running without breaking the bank. Worst of all is buying meter & it doesn't work. No returns on electrical tools as they say.

Regarding Triumph electrical system, it's about a primitive as it gets. Very basic, very simple. The alternator is so low output it just barely keeps up with demand, so long as motor is spinning over at faster rpm. Above 3000 it's not so bad on out put. City riding with many stop lights is not so good. Turning on headlights with original bulbs the alternator is about maxed out. City riding can be a struggle to keep battery charged. Really the alternator puts out 100% it can depending on RPM. Output directly related to RPM. Again max is not much. If the voltage reaches a threshold of about 13.5v the Zener becomes active & starts passing current to ground. The current is converted to heat. There is no voltage regulator. Just the extra is sent to ground. With original bulbs lights on, you'll find very little is sent to ground even at higher rpm. That is how close output is matched to consumers. You get a very light weight system. Very simple low cost bridge rectifier (diodes are built into the cooling discs). A simple Zener to take extra current to ground. Very low cost & simple. Since charging system is so weak at lower RPM a good battery is very desirable.

There is no provision for electrical interference like a car would have. No need. No radio, etc. This allows for solid wire spark plug wires with no suppressors or resistors. As was stated above this is why it makes some meter go crazy. I don't really know.
Don

 

Hi Don,

There is no voltage regulator.

Regrettably not correct.

Triumph fitted a Zener diode from '64, first just to the Thunderbird, then to all non-ET models/versions from '66. The Zener is both a Volts and Amps regulator; read the Zener test in Triumph workshop manuals; ime, the maximum DC Volts is specified between 15.2V and 15.5V depending on the manual. Then certainly Boyer-Bransden's EI fitting instructions say DC should not exceed 16V.

If you measure unregulated AC Volts even with a load, you'll see they're well in excess of those values; the major problem with currently-available new Zeners is certainly some have been shown to allow DC Volts well in excess of the above values.

Before Zeners were fitted as standard, Volts and Amps regulation was a combination of the battery, bulbs and magnetic flux within the alternator; if any of these failed, they then caused the failure of other components. Aside, the lack of regulation is one reason why ET alternators remained very low-output.

Hth.

Regards,

 

You might consider fitting one of these USB chargers to the bike. They have a constant voltage readout so an effective voltmeter when out on a ride. I have these on all my bikes and they are about £8 on ebay. There are a few different type available and i have a very small unit of this type on the T120r without the large 12 volt power outlet. I use it for satnav and phone charging using the usb sockets.

 

Hi,

1972 TR6R
digital multimeter to my battery, I get readings of 12.6. I then start my bike and the numbers are all over the place.

From numerous similar posts over years in various forums, regrettably usually by Americans, seems the problem with (cheap?) meters sold there is the meters' electronics don't have emi (electro-magnetric interference) suppression. Probably not a problem on most vehicles as their makers have supplied them with suppressed HT components, some for many years. But old Britbikes weren't ever supplied with suppressed HT components.

Should I buy an analog multimeter

You could do, or just a (more-expensive?) digital meter with better emi suppression?

Hth.

Regards,

 

There is no voltage regulator. Just the extra is sent to ground.

That is shunt regulation. It’s a short circuit across the rectified alternator output, rather than “to ground.”

That is how practically all regulators that can be fitted to an old Triumph work. The modern reg/rec boxes have an electronically switched shunt, rather than just putting all the current through a big Zener.

 

That is shunt regulation. It’s a short circuit across the rectified alternator output, rather than “to ground.”[

That is how practically all regulators that can be fitted to an old Triumph work. The modern reg/rec boxes have an electronically switched shunt, rather than just putting all the current through a big Zener.

.I've been told, if I understand it properly, the shunt occurs on non rectified or AC current on some regulators...and a bit more complex than just shorting to ground especially with some bikes having 350 watt alternators...

 

Both multimeters I have used are regrettably cheap versions. One is the popular Harbor Freight cheap model and the other is a similar cheap model I bought on Amazon in 2015. Interestingly, when I was running points I was able to get readings from the battery terminals just fine. Recently I have upgraded to a Boyer EI and now I get the erratic readings. Curious if somehow the electronic ignition is causing the interference. Anyways, I purchased a cheap analog version and will update if that fixes the problem. Thanks again for all the responses.

 

Hi,

Curious if somehow the electronic ignition is causing the interference.

Uh-uh, the electronics draw a miniscule amount of power. However, it's now firing both coils every crank revolution instead of only one. So double the emi than with points?

Hth.

Regards,

 

I use a Simpson 260 analog for vehicle work. They came out just before WW2 and I believe still made right here in the USA. They are big, heavy and thick plastic. You could knock an intruder unconscious with a blow to the head..They are safe to use on modern electronics...
New they are $300....I got mine on Ebay for 50 bucks..you can also buy a 0-20 volt panel mount gauge for 10 bucks...Add some foam and tape, wire leads and there you go, a dedicated volt meter

 

Hi NewbornLobster. Interesting on how your cheap meter used to work with points. I had two Cen-Tech meters. Neither would work on my bike, '73 Tiger with points. I only used one of them on '69 Bonnie with points. It wouldn't work either. Not running they worked fine.

I don't why the change after installing Boyer. A guess is higher spark voltage resulting in more interference??

You're the first person I've heard of than Cen-Tech worked with motor running. Harbor Freight gave hundreds away in my area free. Lots of Harbor Freights in my region. Lots of owners have them.

The point I had of sharing meter info was to find an affordable meter that would work running. Why spend $80 for a meter if a $25 one works fine for us?

Exactly what is your 2nd meter that doesn't work? The idea is to state exact brand & model so we know your experience.

What about the Innova brand? Would they work? Starts at $20 for 3300a, $35 for the next step up 3320.

Don

 

I have this one at home,

and its modern digital equivalent at work which also works perfectly with the engine running but doesn't feel as right!

 

Call a Zener connected across a battery a "shunt" if you must but, because it's connected to both battery terminals, by definition the Zener must be a resistance, or any battery will supply sufficient Amps for a short period to damage wiring insulation and similar?

Yes, a battery can supply sufficient current to damage wiring, but I can’t see how battery voltage gets high enough to make the Zener conduct. The Zener stops the battery voltage ever getting that high.

 

Afaik, they're "regulator/rectifiers" because they regulate first then rectify, so they're only rectifying to satisfy the DC load; other way 'round, they'd be "rectifier/regulators".

Not always, apparently. Understanding Motorcycle Voltage Regulator Wiring | Homemade Circuit Projects

Similar philosophy here: Regulator/Rectifier

 

Hi TT,

Just 'cos it's on t'internet doesn't make it correct? Have a look at "NickL's" past posts ...

EDIT - thinking about it, if a reg./rec. rectified alternator output before regulating, the reg./rec. would have to dissipate all the consequent heat itself, stator and wires in between couldn't be used to help. Regulating after rectifying is why Zeners have to have such a large heatsink.

Hth.

Regards,

 

Hi Newborn,
Before changing my meter, I think I would first check it on another vehicle.
I think that I would also check that the HT system has sufficient suppression built in (5000 ohms) either from resistor spark plugs, resistor plug caps or resistor HT leads. Only of the above not 2 or 3 of the above.
I would also ensure the return path from the engine to the battery, I like to fit a dedicated braided lead rather than rely on the engine bolts/frame control cables , etc.
I would also check the rectifier, make sure all diodes are OK so you getting full wave rectification rather than faulty half wave rectification.
Only then would I look to my multimeter to be over sensitive.

regards
Peg

 

Hi Peg,

would also check that the HT system has sufficient suppression built in

Recently I have upgraded to a Boyer EI

OP doesn't say but, if it's an analogue "MicroMark", doesn't need it. T160's with Rita, T100 with B-B Mk.3, none have suppressive HT components, none cause even cheap British-bought meters any problems. Not sure I see the point of adding electrical resistance just to get a crap meter to work?

Hth.

Regards,

 

Hi, We've kicked this Harbor Freight meter around several times on club rides. I've never heard of one working with motor running. I was most surprised when he said it used to work. To be clear this is the Cen-Tech 7 function meter $6.49. This used to be $4.99. Raised price several months ago. I was there not too long ago & the meter looks unchanged visually.

Looking a spec sheets for various meters they don't say if they are shielded from stray voltage interference or not. Fluke spec sheet mentions it though ($170.00) model 114, ghost voltages. Is that what we are seeing ghost volts with Harbor Freight? I don't know. How does does low impedance effect the odd operation?

To test the meters in question you'd need to try in on another Triumph. They work perfectly on running cars. I've tested hundreds of cars during battery changes etc.

I wonder what the Cen-Tech 11 function $22.99 would do? It has 20A ammeter built in. With another working volt meter hooked up, you could test Zener with this one.
Don

 

I too am interested in recommendations for digital multimeters that work on British bikes. I have a pretty basic RadioShack model from years ago -- it is unable to read voltage when bike is running. I have to rely on an analog meter to obtain any kind of reading when engine turning over, and it is rather inaccurate at best.

 

vintage simpson 260 analog meters are cheap on ebay

lol

i guess this is old newz

 

First question is your bike set up with DC generator or Alternator if it is Alternator then It;s not your meters it's your voltage regulator switch to AC and see if you get voltage readings more then likely your bridge rectifier has a bad diode and AC is leaking through.
If you have a DC generator then read the out put side of generator and see what voltage you are producing (engine running).

 

First question is your bike set up with DC generator or Alternator

Have you never even seen a 1972 Triumph?

 

Hi Don -- I just received a Bechman Tech 310 multimeter hand-me-down from a family member. Reads voltages quite nicely while bike is running, and shows just how much it can bounce around (~1/2 volt). Looks to be a quality instrument. They are going on eBay for reasonable money.

 

Did you perform an AC voltage test as well to make sure your rectifier is not breaking down. Typically with engine running charging outputs can be between 13-14 DC volts.

 

Recently I bought one of those cheap automotive USB chargers with voltage measurement, similar ti this one

https://www.amazon.com/-/de/YonHan-Charger-Waterproof-Aluminum-Voltmeter/dp/B07FXH5ZZK/ref=sr_1_3?__mk_de_DE=%C3%85M%C3%85%C5%BD%C3%95%C3%91&crid=JN159SBLRJCZ&dchild=1&keywords=usb+charger+automotive&qid=1598962761&sprefix=usb+charger+auto%2Caps%2C226&sr=8-3

Connected to my T140 it gives stable measurements:

• 12.6 V with motor off and fresh battery
• with motor running > 13.0 V from 2000 rpm and
• 14.6 V at highway speed (~4000 rpm).

regards
Oliver

 

Hi Guys, Thanks for the replies. Now we have 2 more options we know works. Actually that's a big deal.
Don