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Almost ready 74 850 boyer problem

Classic Norton Commando Motorcycles.

Almost ready 74 850 boyer problem

Postby Joe Schlaberdowski » Tue Jan 03, 2017 6:53 am

Bought a 74 850 that's almost ready. With plugs out and grounded there is an intermitant weak orange spark. Battery is brand new gel type and fully charged. With plugs in getting gas to the mikuni and there is a faint white puff out the pipes, but not a hint of firing. Noticed when I shut it off there is a hot blue white spark at the plugs. I didn't instal the Boyer ignition and know nothing about it. Emailed Boyer and they said, "Make sure battery is charged." But I told them it was. Is everything normal and it's really a timing issue? Or do I have a problem with the setup or even the Boyer unit itself. Read that a good spark on shutoff indicates circuit box of the Boyer is ok -- not sure. Anyway, it's still winter so I have time.

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Re: Almost ready 74 850 boyer problem

Postby grandpaul » Tue Jan 03, 2017 6:57 am

Double-check all electrical connections, install new spark plugs, and make sure the plug wires are nice and snug.

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Re: Almost ready 74 850 boyer problem

Postby L.A.B. » Tue Jan 03, 2017 7:41 am

It could be worthwhile going through the installation procedure just to make sure it has been set up correctly:

Boyer troubleshooting guide:
http://vintagebikemagazine.com/technica ... -shooting/

As this Commando is "almost ready" and probably not going to be the subject of a rebuild I've moved this thread to the main section at least for the time being.
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Re: Almost ready 74 850 boyer problem

Postby kommando » Tue Jan 03, 2017 7:45 am

The blue spark when you turn off is normal boyer behaviour, shows that the box at least is working.

Most older MKIII ignition units will produce a spark when switching the ignition on or off, if this is so and sparks are produced on all cylinders then the ignition coils must be in good order.


Sounds like a timing issue but you need to check everything to confirm it is set up correctly.
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Re: Almost ready 74 850 boyer problem

Postby concours » Tue Jan 03, 2017 8:15 am

Bypass the ignition key, and kill button by using a jumper from battery to power the Boyer.

Also, a whiff of starting fluid will tell right away if we ARE or ARE NOT getting fuel into the combustion chamber. Barring that, a tiny shot of gasoline in the plug holes will do it too.

Also, enricher ON the Mik, throttle closed, correct?

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