74 Commando Boyer Testing

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MarkDeaton

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Hello everyone! Newbie here. I recently acquired a 74 Commando 850 with a 73 engine. The wiring harness was pretty buggered up so I removed it and ordered a new one. I replaced the points with a Boyer electronic ignition.

My question is this: without the wiring harness is it possible to wire up the ignition, coils etc. just as a test to verify spark? I do not have a battery yet but I have a 12v jumper pack. I read somewhere to connect the positive side of the battery straight to the white wire on the Boyer box but I'm not sure where the negative should go. I have brand new coils and plug wires.
 
Thanks. Does it make a difference if there is no wiring harness currently installed and it's a positive ground setup?
 
You only need the pickup wires from the Boyer stator and power to the coils and box per the link LAB provided.
 
850commando said:
LAB, do you not also need a ground wire to the cyl head?
Click to expand...

Yes, I was just about to mention that! :)

The harness isn't required although a ground connection between the engine and battery positive is needed for the spark plugs.
 
Mark,
Make sure that you read all the instructions on the Boyer before you try anything.Also the troubleshooting section.There is plenty of information here to see.
Mike
 
MarkDeaton said:
Which is the "2nd coil"? You are talking to a newbie sir ha. Got the new coils and plug wires today. Just sitting here staring at the stuff being a bit cautious.
Click to expand...
Boyers are a wasted spark system in which both plugs (and coils) fire simultaneously and must be wired as such. Each cylinder has a "wasted spark" at 28-32 degrees btdc (depending upon your setting) during the exhaust stroke.
 
Protect your new Boyer. It's a + grounded system all over the bike. Negative - is the power source. Do not experiment or you will be purchasing a new voltage regulator , or if lucky at least another fuse. Look up fuse blow ratings on this forum. 2 ratings for that. British blow or America fuse ratings blow.
 
L.A.B. said:
Yes, I was just about to mention that! :)

The harness isn't required although a ground connection between the engine and battery positive is needed for the spark plugs.
Click to expand...
I connected a wire to the battery positive per your instruction, tapped it quickly on the head and got a pretty nasty spark. Does + actually mean - on the coils? This positive ground stuff is making my head spin.
 
Make sure that you have the plugs securely grounded before powering up the Boyer or you will prove that it doesn't work (for long).

A stand alone ignition system can produce comforting results. Consider your power supply as a battery and wire the Boyer according to the instructions.

Best.
 
MarkDeaton said:
I connected a wire to the battery positive per your instruction, tapped it quickly on the head and got a pretty nasty spark. Does + actually mean - on the coils?
Click to expand...

No. The 2nd coil (+) from the Boyer box connects to the test battery(+). It's possible that touching the wire somehow triggered the Boyer box.
74 Commando Boyer Testing


MarkDeaton said:
This positive ground stuff is making my head spin.
Click to expand...

Because you are probably overthinking which isn't unusual for someone more used to negative ground.
 
MarkDeaton said:
Oh wow thank you. This helps immensely. I guess I'm a visual type.
Click to expand...
glad i could help!

Hello everyone! Newbie here. I recently acquired a 74 Commando 850. The wiring harness was pretty buggered up...
Click to expand...

i can honestly say, been there, done that. in fact, that was me two years ago. my harness was so boogered up, there was no salvaging it. started fresh - brand new service replacement lucas assembly. all is good!
 
Disconnect the black yellow and black white wires that run from the Boyer stator to the Boyer black box. Do the disconnect up near the Boyer black box where there should be pull apart bullet or spade connections.
Pull the spark plugs out and attach the high tension leads. Ground the plug bodies ( steel threaded part) on the head by laying the plugs on the head . Turn ignition power on.
Use a jumper wire, if needed, to make and break a connection between the short black yellow and black white wires that come from the Boyer black box.
This should result in a spark at the plugs.

Glen
 
worntorn said:
Disconnect the black yellow and black white wires that run from the Boyer stator to the Boyer black box. Do the disconnect up near the Boyer black box where there should be pull apart bullet or spade connections.
Pull the spark plugs out and attach the high tension leads. Ground the plug bodies ( steel threaded part) on the head by laying the plugs on the head . Turn ignition power on.
Use a jumper wire, if needed, to make and break a connection between the short black yellow and black white wires that come from the Boyer black box.
This should result in a spark at the plugs.

Glen
Click to expand...
I got spark!!!!!!!!!!!
 
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