The single cylinder motorbike tacho problem.

[oldbeaver]

Hello everyone! I have a single cylinder Suzuki GZ150A, very nice, quiet, look bigger. It doesn't come with a factory tachometer.

I installed a universal analog tacho and feed it with the pulse signal of the coil.
As the engine is a four stroke, it has one spark every two revs, therefore, my tacho shows half the real revolutions of the engine. It just shows the pulses it receive. Not a fault, it says the true.
Was it a two cylinders, it would work fine.

I don´t know what would happen with a three cylinder or a four cylinder bike. There is no manual attached.

Now, how can I fool the tacho and make it show double as much pulses, meaning the real revs?

That is my question. Sorry for my limited English.

Some people has diesel trucks which don´t have tacho either. They get a signal from the alternator. Do you think guys that a motorbike alternator produces pulses suitable for tacho purposes?

Greetings to all and my wishes od good biking.

[Riejufixing]

[WD Forte]

I bought a pretty electronic analogue tacho on an impulse a while ago which was a car type.
when fitted to my bike on one of the ignition coils it gave half the actual rpm.

DUH!
Of course.
Had I sat down a thought about it before hand I would have known better.

kwote:
"how can I fool the tacho and make it show double as much pulses, meaning the real revs?"

I did buy a 4011 IC to build a 'two pulses out for each one in' circuit but lost interest as I've never been much bothered about having a tacho and didn't have room for it anyway.

It also occurred to me that as I have a twin cylinder wasted spark type I could have tapped both coils using optos and fed it that.

I did make one using an Arduino Nano+ opto for larfs but i was like

"Tacho? we don need no stinkin tacho" by then
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bikers smell of wee

[The Shaggy D.A.]

I've bought a cheapo tach that's for cars as an experiment. I'm betting on it being a frequency to voltage chip like an LM2907, and the 4-6-8 cylinder selector switch is just a different resistor value to adjust the scale. If I'm right, it'll just be a case of sticking a variable pot in to replace the switched resistors, find the value that works, and sticking in a fixed one.
____________________
Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[weasley]

[stinkwheel]

Have you checked in the back for a DIP switch or moveable jumper connection or in the connector for a looped wire (that may be designed to be cut in some circumstances)?

Been a long time since I looked into them but most aftermarket tachos will have two modes, either single spark per cycle or a wasted spark.

Doesn't really matter how many cylinders it has, the coil generally pulses either once or twice per revolution.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[oldbeaver]

[oldbeaver]

[Pete.]

Remove dial, place on scanner, import to PC, open in GIMP/Photoshop etc, edit image to adjust the RPM scale, print on glossy paper, glue glossy paper to dial, re-assemble tacho and fit.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[The Shaggy D.A.]

...except if the rev counter is calibrated for 4 cylinders and you only have one cylinder that red lines at 6000, the needle will only be using a quarter of the scale and be pointing where the 1500 was.
____________________
Chances are quite high you are not in my Monkeysphere, and I don't care about you. Don't take it personally.
Currently : Royal Enfield 350 Meteor
Previously : CB100N > CB250RS > XJ900F > GT550 > GPZ750R/1000RX > AJS M16 > R100RT > Bullet 500 > CB500 > LS650P > Bullet Electra X & YBR125 > Bullet 350 "Superstar" & YBR125 Custom > Royal Enfield Classic 500 Despatch Limited Edition (28 of 200) & CB Two-Fifty Nighthawk > ER5

[Pete.]

[WD Forte]

You took the innards out and they broke eh?
and you fucked about with the pot which is for fine tuning/adjustment/set up, I'll bet

You are Frank Spencer and I claim my five ponds

In case you're not trolling
"As the engine is a four stroke, it has one spark every two revs"
Your bike, like many, gives one pulse/spark per revolution
RTFM! I did
I bet that car tacho like the one I have, is designed for 2/3/4 pulses per rev
( 4 /6/8 cylinder car engines)
____________________
bikers smell of wee

[weasley]

[Teflon-Mike]

[WD Forte]

yeah, wot he said
I bet most 4 stroke 125s have a wasted spark system and many others too
____________________
bikers smell of wee

[oldbeaver]