Norton commando spark problem

So my 69 norton commando 750 ran when parked a month ago. it has boyer ignition. it docent have any spark but when you honk the horn it does ask me how i found out while holding the plug and wire. and i have to brand new 6 volt coils which tested good. I'm combing through the wiring now could it be the switch? this seem strange to me. and it has 12.5 volts

Have a read through this. Single most important test is running the jumper as shown in the diagrams about 3/4 of the way down. This will tell you if the Boyer is getting enough volts to run. Is your Boyer a MkIII or IV?
The III's are more sensitive to low voltage than the later IV version.
http://vintagebikemagazine.com/technica ... -shooting/

its a mark III i tested the breaker plate its good.

Check the earth route, both boyer to earth and engine to earth.

Generally the Boyer bits are good. It's the lack of voltage to run them that drops off somewhere between the battery the boyer white wire and causes them to malfunction. Thats why I suggested you run the jumper test first.
Two likely spots for voltage drops are ignition and kill switches. After that probably duff batteries. Even though batteries will charge up they often won't hold a charge. You need to load test them. Quick and dirty is to turn the headlight on for two minutes. Measure before and after volts. Should not drop more than 1/2 a volt or so.

if it ran just fine two months ago then it is very doubtful a ground or wiring issue decided to appear while it was parked in your garage

I agree you should fully charge the battery and try starting it again

What is the voltage of a fully charged battery?
A typical 12-volt lead-acid battery must be taken to approximately 14.2-14.4 VDC before it is fully charged. (For 24 volt systems, double these figures.) If taken to a lesser voltage level, some of the sulfate deposits that form during discharge will remain on the plates.

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Hi,
Funnily enough when I switch on the ignition of my 69 750 I always bib the horn , crazy but it tell me the ignition is on and no it doesn't bib if the ignition is off. But at the end of last year the old bib test failed a couple of times but a "shouggle " of the key had it working again but it conked out on the way home again no horn. Changed the ignition switch and problem solved . My bike has a ducon switch so does not have a kill button.

The ignition switch is not expensive and quick to change so worth a shot if it's old it may be past its best and on the way out.

jg

ZRMiller said:

So my 69 norton commando 750 ran when parked a month ago. it has boyer ignition. it docent have any spark but when you honk the horn it does ask me how i found out while holding the plug and wire. and i have to brand new 6 volt coils which tested good. I'm combing through the wiring now could it be the switch? this seem strange to me. and it has 12.5 volts

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This is a shot in the dark. It's my understanding that a Boyer will spark with the ignition on and then hitting the kill switch. I have seen people recommend this as a test. So if you have a weak battery, with the ignition on and hitting the horn button is like killing the power to the Boyer because of the high draw of the horn. It's possible your battery is weak or on the way out. Static testing your battery and showing 12 volts is not always giving the whole story. You might have a 12 volt surface charge but not enough power to fire the bike off. I would try and find a good battery tester or better yet a good battery and then try to start the bike. After following this forum for a while it seems the two biggest problems that appear after non-use are clogged idle jets and weak batteries.

Pete

1up3down said:

it is very doubtful a ground or wiring issue decided to appear while it was parked in your garage

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Why?