Does anyone know anything about Yamaha YG1s?

Prisondawg

Prisondawg

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I just got a yamaha 1963 YG1 .

But I am not getting spark.

When I turn the key on nothing seems to work except for the horn....

All the wires are connected. I got my ground wire screwed down to the same the place as the screw where the ignition goes.

I just got a NOS ignition switch so it should be fine. New spark plug.

I have a new set of points coming in so I hope that fixes it.

But what would be a good pathway to test some stuff with a multimeter.

What is the minimum I would need to get spark.

How does the rotor produce spark?

There is unfortunately not much info out there , but this community is amazing with the XS650 so I figured maybe there's a yamaha enthusiast that has had one of these before.
 
Prisondawg said:
What is the minimum I would need to get spark.
Click to expand...

Iirc... those old Yammies used a magneto iggy. Should have a rotor (magnet) and a stator coil to make electricity. That's fed to the coil and passed on to the points and condenser to trigger the coil. 'Course, you need the plug and plug wire too. Simple reliable system. All the iggy switch does is ground the stator coil to kill it. Show me some pics of the engine with the mag cover off and maybe it'll jog the ol' grey matter some more. ;)
Stator and iggy coil might even be one and the same... a little fuzzy on that.
 
Jim said:
Iirc... those old Yammies used a magneto iggy. Should have a rotor (magnet) and a stator coil to make electricity. That's fed to the coil and passed on to the points and condenser to trigger the coil. 'Course, you need the plug and plug wire too. Simple reliable system. All the iggy switch does is ground the stator coil to kill it. Show me some pics of the engine with the mag cover off and maybe it'll jog the ol' grey matter some more. ;)
Stator and iggy coil might even be one and the same... a little fuzzy on that.
Click to expand...

I have this one readily available. If you have need for any others let me know.

One question I have is, will the lights run without the engine running ?

I know one of the coils here on the stator is a lighting coil..I think the other coils feeds the ignition coil which is located within the frame.
 

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I might be thinking of another bike. My memory says one coil on top of the other... not a left and right. Iirc the top was the iggy coil and the bottom was for lighting. Maybe I'm no help after all. :(
 
Here is a wiring diagram, likely the points need cleaning. Ignition switch grounds out the black wire at coil to stop motor . To check points put ohmmeter on black wire feeding coil and a good ground. Rotate flywheel slow by hand and as points open or close should see couple of ohms difference. If no change likely points dirty . New points usually have oily coating on them so I clean them before installing .
Looking at diagram and no voltage regulator used so Yamaha has charging coil with two outputs, daytime no headlight basically a trickle charge useing green wire to maintain battery without overcharging it. Turning ignition switch to lights provides 6 volt AC on yellow wire directly to headlight circuit. Small loads horn, brake light and neutral light are always 6 volt DC directly off battery.
6504B130-AB67-493B-A05B-C57F6C677D30.png
 
Hi
Not familiar with that bike
But it appears to have a battery then check Voltage so it is OK
Then check the Points gap
And perhaps clean them a small file or Carborundum paper
If that Schematic is correct
And You have a Working horn --- The Question is why not --- A Neutral Lamp since it appears to be on the same Wire
??? A Short in the lamp Housing ??
 
Usually these small bikes have AC lighting, the batter only powers the horn,neutral light, brake lamp and indicators if fitted.
The engine has to run for the lights to work.
As Jim said the ignition switch grounds the low tension in the off position. As a result if you don’t have a key, simply isolate the ign switch and it should make a spark.
 
Still no spark.
I'm not what's missing

New ignition switch
New points
New plug
The points open just as the line on the rotor matches the line on the stator
The battery is grounded to the same screw that holds down the ignition switch.
The horn is the only thing that works. I get no tail light brake light or neutral switch.

Why would the horn work but no other lights (I assume that the head light wont work unless the bike is running)
 

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Prisondawg said:
Still no spark.
I'm not what's missing

New ignition switch
New points
New plug
The points open just as the line on the rotor matches the line on the stator
The battery is grounded to the same screw that holds down the ignition switch.
The horn is the only thing that works. I get no tail light brake light or neutral switch.

Why would the horn work but no other lights (I assume that the head light wont work unless the bike is running)
Click to expand...

Sir if this is AC system I am off coming from a XS 650
However something to consider
I would Disconnect the Blue Coming out of the Ignition ( Main ) switch labeled L on the schematic earlier in this thread --disconnecting the lamps.
Kicking it with the sparkplug against the engine block looking for sparks
If nothing I would then disconnect the Brown out of the Ignition ( Main ) switch labeled C Kicking it with the sparkplug against the engine block looking for sparks.
( It can spark but at the wrong time )

With L and C disconnected ..the only thing connected would be pretty much the Ignition
EXCEPT the yellow coming out from M1 6 o clock I don't know what that one does
Since I don't know these systems please consider if there is any risk. Disconnecting in this manner .And wait other messages if it can be done
 
Last edited:
Magneto systems don't work with a points gap the way a regular system does. You don't really set the gap and measure dwell. You have to set the points to open at a specific point of rotation in degrees or in piston height. You need either a degree wheel or a dial indicator to measure piston height. the gap is irrelevant if the points open at the right time. You cannot measure this with a multimeter, you need a device called a buzzbox or a lightbulb ran is series with battery voltage and the breaker. If its not set almost dead perfect it will not run. Points shoulds open @ 1.8mm BTDC
 

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