Noob help

Ok, So my mk2a is only occasionally firing on the right cyl. I confirmed this with the obvious backfire from the right peashooter and the timing light on the right plug only blinked now and then. Im off to the store to get the correct plug wrench, (dangit!) so I can further confirm this. I will get a new plug or two while Im there,(N7Y) and then see what happens. It has the boyer ignition and the left side seems to run fine and has constant blinking on timing light. *I did check the timing at 31 degrees with around 4500-5000 rpm for a second and had to throttle down cause the right side was backfiring.

Soooooo. Coil? Plug? Dunno. Any help would be appreciated.

Once again, Thanks in advance.

William

What model of Boyer ?

Early versions are famous for the wire breaking, or almost breaking, right where the wire solders on to the circuit board.

f you jiggle it about, it will probably make good contact and run.
Resoldered, it will reliably run....

hth

One coil, or two? If two, swap spark plug wires to opposite coil. ( left plug fired by right coil) If left side starts backfiring, bingo! Bad coil.
If not, or only one coil, swap wires themselves from one side to the other, and see what happens. If left side starts barking, then its a bad wire.

Thanks Caddy Chris,

It was the plug wire.

Already got a new one and "Nell" runs like a top. I dunno why I didn't check that first....Hummmm. Noob move!

Thanks again!

William

No prob! Kinda one of those " been there, done that" things. Glad you got it figured out.
Id replace both of them.

"Faulty spark plug wire"

Faulty spark plug wire ??
What is there to go wrong .... ?

Rohan said:

"Faulty spark plug wire"

Faulty spark plug wire ??
What is there to go wrong .... ?

Click to expand...

The main failure of wires is breaking or breaking down of the conductor (e.g. broken copper wire within the sheathing). The second most common failure is breakdown of the insulation that allows arcing to ground.

Some years ago my car began stumbling. I messed around with various 'fixes' and could not figure out the problem. A friend recommended that I put the car in my garage late at night, open the hood, start the car, then turn out the lights and look under the hood. I was treated to a beautiful light show as blue arcs jumped from the wires to various points on the engine. I replaced all the wires and the car ran perfectly (or as some say in England - Perfick).

The wires / sheathing / insulator can crack due to age and vibration. I just had a friend suffer from a cracked insulator. Kind of insidious because as pointed out you can't really see anything wrong. First thing is to swap the wires and see if the problem moves to another cylinder. I do that first, then the plugs because it's really easy to do. Then the coils.

Shortly after buying my bike it refused to start. Inspection showed that the p.o. hadn't plugged one of the wires fully onto the coil, causing the spark to jump the gap. Eventually the conductor burned away and turned to a green crystaline oxide. The coil was damaged beyond repair.
I've also learned that cleaning dirty wires with carb cleaner is a bad idea as it breaks down the insulation, and allows wires to spark over to whatever ground is available.
Running wires parallel or twisted also can result in inductance. Not really a concern in a dual fire system, but can be a real pain in the butt with distributor fired multi cylinder engines, causing cylinders to preignite.