Ignition Woes

Bonwit · Jun 29, 2015

My '74 Commando came from the previous owner with a Boyer ignition. I don't know how old it is, but I believe it's been on the bike for a long time, Maybe 10 or 15 years. I haven't had to give it much thought, as it has always done its job. Several hundred miles ago, I was riding with a group far from home, when, accelerating out of a small town, the engine decided to quit. This was a very unusual occurrence, as the bike had been pretty reliable up to then. I kicked and sweated, finally giving up and just letting it sit. After a awhile, it started as though nothing had happened and I continued my 300 mile ride home without another problem. It's continued to be trouble free for many months.

Yesterday morning I tried to start the bike and just could not get it to kick over. I decided that the battery was low and put it on its charger for the rest of the day. After a full charge it still wouldn't start. I did note though that on a couple of occasions when I went to turn the key off, I got a loud backfire. Hmmm.

So I connected an ignition test light to the spark plug and sure enough, no spark. What's strange though was as I turned the switch to OFF, I got a spark. Okay, my ignition switch is pretty new, so I didn't focus on that. Instead, I checked all the wiring harness connections I could easily get to. The yellow/black wires to the stator plate were connected, everything looked okay as I expected. My wiring harness is pretty clean, having been replaced a couple of years ago. I also pulled the timing chest cover and checked those connections and wiggled the wires around a bit. They seemed okay. After doing all this, I reconnected the test light and kicked it. It started the first kick! Afterward, I checked to see if I got that spark as I turned the switch OFF as before. Nope. no spark there, but strangely, I got a weak flash when turning the switch ON! Is it supposed to do that?

What's going on here? I admit I know very little about this Boyer system. The bike seems to be running fine now, though I don't want to take it too far from home until I get to the bottom of this. It's a very frustrating situation when you can't trust your bike!

I'd appreciate any insight you guys may have.

johnm · Jun 29, 2015

Very common to get a spark when turning a boyer on or off.

What you have described are text book symptoms of a Boyer with a broken wire down near the pickup coils monted on the plate at the end of the camshaft. Just before they are soldered to the backing plate.

The wires break inside the plastic sheath and look perectly fine unless you pull and twist them. Its also common for the ignition to come back after the bike cools down.

the best way to test is to use a multimeter to test the resistance in the coils. From the web Britiish Cycle supply " Using a multimeter check the resistance of each pickup coil (should be approx. 65 ohms or 130 ohms across the two coils) and the total resistance across the wires or terminals. With the meter still attached, run your fingers around the coils, if the resistance changes there could be a broken winding inside. Attach the meter across the trigger plate’s wires and pull on them. If the resistance changes you could have a broken wire."

o0norton0o · Jun 29, 2015

It could be as simple as worn out ignition switch contacts. Maybe make up a male to male jumper wire next time the bike wont start and "jump" the switch out of the loop to see if that fixes the issue...

Bonwit · Jun 29, 2015

johnm said:
Very common to get a spark when turning a boyer on or off.

What you have described are text book symptoms of a Boyer with a broken wire down near the pickup coils monted on the plate at the end of the camshaft. Just before they are soldered to the backing plate.

The wires break inside the plastic sheath and look perectly fine unless you pull and twist them. Its also common for the ignition to come back after the bike cools down.

the best way to test is to use a multimeter to test the resistance in the coils. From the web Britiish Cycle supply " Using a multimeter check the resistance of each pickup coil (should be approx. 65 ohms or 130 ohms across the two coils) and the total resistance across the wires or terminals. With the meter still attached, run your fingers around the coils, if the resistance changes there could be a broken winding inside. Attach the meter across the trigger plate’s wires and pull on them. If the resistance changes you could have a broken wire."

Just the information I was looking for. Thank you! I'm leaving for vacation tomorrow, so when I get back I'll check this out. If it is the pickup coil, do you know if just that part is available?

o0norton0o, the ignition switch is quite new, so I'm not suspecting it (doesn't mean there couldn't be an issue though). Making up a jumper seems like a good thing to have onboard anyway.

ashman · Jun 29, 2015

You can buy just the pick up coil, but if its a broken wire you can replace just the wire, Boyar's are pretty reliable mine was on my Norton for 32 years before replacing it with the J/H and my old Boyar went in my mate's Norton and was still going when he sold it, they will spark when the ignition is turned on, in the 32 years it was on my Norton it had fired up by just turning on the ignition switch and the pistons just at the right position, it freaked me out the first time it did it, so make sure you are always in neutral when you turn on the switch, just incase.

A funny story, once i had a mate sitting beside my Norton on the kick start side of the bike and I was setting on the other side we were having a few beers at the time and I turned on the ignition to check something when my bike fired up, my mate didn't say anything for awhile till it got the better of him and asked how it started when I didn't kick it, I said in a straight face and just said magic, I never told him and after a few years it kept nagging him and asked me one night, before I told him the truth, he was killed in a bike accident a few weeks later, that was over 27 years ago.

Ashley

johnm · Jun 30, 2015

Yes. If its a broken wire you just resolder it.

I have a special reason to remember this problem. I have owned my Commando about 38 years. The only time I was left by the road it was this issue !

o0norton0o · Jun 30, 2015

If your switch is new, you can probably look elsewhere for the issue. A 40 year old switch is more likely to need checking than a new one.

check your coil resistance, check for breaks in the wiring to the boyer plate as suggested because they are known to break at the bullet connectors, and check your grounding or even add a ground or two to make sure you have a good ground wire. Just recently, my directional signals stopped working. It wasn't the switch, the bulbs, or the flasher unit. I added a dedicated ground to both bulb sockets and it all worked again... nothing was broken, just a crappy ground breaking the circuit....

ewgoforth · Jun 30, 2015

Bonwit said:
My '74 Commando came from the previous owner with a Boyer ignition. I don't know how old it is, but I believe it's been on the bike for a long time, Maybe 10 or 15 years. I haven't had to give it much thought, as it has always done its job. Several hundred miles ago, I was riding with a group far from home, when, accelerating out of a small town, the engine decided to quit. This was a very unusual occurrence, as the bike had been pretty reliable up to then. I kicked and sweated, finally giving up and just letting it sit. After a awhile, it started as though nothing had happened and I continued my 300 mile ride home without another problem. It's continued to be trouble free for many months.

Yesterday morning I tried to start the bike and just could not get it to kick over. I decided that the battery was low and put it on its charger for the rest of the day. After a full charge it still wouldn't start. I did note though that on a couple of occasions when I went to turn the key off, I got a loud backfire. Hmmm.

So I connected an ignition test light to the spark plug and sure enough, no spark. What's strange though was as I turned the switch to OFF, I got a spark. Okay, my ignition switch is pretty new, so I didn't focus on that. Instead, I checked all the wiring harness connections I could easily get to. The yellow/black wires to the stator plate were connected, everything looked okay as I expected. My wiring harness is pretty clean, having been replaced a couple of years ago. I also pulled the timing chest cover and checked those connections and wiggled the wires around a bit. They seemed okay. After doing all this, I reconnected the test light and kicked it. It started the first kick! Afterward, I checked to see if I got that spark as I turned the switch OFF as before. Nope. no spark there, but strangely, I got a weak flash when turning the switch ON! Is it supposed to do that?

What's going on here? I admit I know very little about this Boyer system. The bike seems to be running fine now, though I don't want to take it too far from home until I get to the bottom of this. It's a very frustrating situation when you can't trust your bike!

I'd appreciate any insight you guys may have.

It should spark if you disconnect the two wires from the pickup plate inside the points cover and touch them together.

Bonwit · Aug 2, 2015

Thanks again for the replies. I'm back home and ready to track down the problem. I have to admit, I've never done anything with the pickup end of the Boyer, so I need some guidance here. The bullet connections should be easy enough to check. They look okay on the surface, but I'll look further. As for the coil wires, how do I check those? Do I need to remove the plate to get to wires on the backside? If I do so, I assume I have to re-time the ignition, correct?

Thanks!

L.A.B. · Aug 2, 2015

http://www.tioc.org/boyer/boyertestnewweb.htm

http://www.boyerbransden.com/faultfinding.html

https://www.oldbritts.com/boyer_testing.html

Bonwit said:
Do I need to remove the plate to get to wires on the backside?

Yes (if you want to check the soldered joints or replace the wires).

Bonwit said:
If I do so, I assume I have to re-time the ignition, correct?

Not necessarily, just mark the plate and housing so the backplate can be replaced in the same position.

Ignition Woes

Bonwit

johnm

o0norton0o

Bonwit

ashman

johnm

o0norton0o

ewgoforth

Bonwit

L.A.B.

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