Continuous sparking- won’t start

[Captjrhill]

Thank you in advance- long time listener, first time poster.

I have a 1979 XS 650SF. I installed the Boyer brans den micro power ignition system and the XSCharge PMA kit about four years ago. Unfortunately, I hadn’t been running my bike a lot

during COVID so when I finally started it up I struggled with only one cylinder running. After getting it running, I had blue smoke coming out. I just finished rebuilding the bike with replacing the pistons (literally had a hole in the top of the piston). Now that the bike is all out back together, I went to start it and it wouldn’t start. I took out one of the plugs and grounded it. After a few cycles of trying to start it, the spark plug has a continuous spark and actually seems to be building up if I don’t turn the switch back fr right away. This continuous spark occurs AFTER I stop hitting the start switch- aka no rotation and it is occurring. I checked around and did not find any wires grounded and all connections seem to be tight. I am not sure where to go from here. Any thoughts would definitely be appreciated!

J.R. Hill

 

[jpdevol]

Wow! I'd guess the piston hole was related to the "continuous Sparking". As the Boyer runs a single, dual tower, coil; and only one side is continuous, I'm also guessing that there's an issue with the pick-up coil or the circuit board

 

[Jan_P]

https://vintagebikemagazine.com/technical-articles/boyer-trouble-shooting/

My guess is the power supply to the Boyer .. Maybe capacitor defect
But having said that I have no experience with PMA at all

If you are having problems getting a spark, even though the box is wired properly, check to see if the engine is grounded to the battery. The ignition box, coils and engine must share a common ground with the battery (or capacitor or Power Box if not using a battery). Do not assume that the engine is grounded by the mounting bolts!!

 

[Captjrhill]

Wow! I'd guess the piston hole was related to the "continuous Sparking". As the Boyer runs a single, dual tower, coil; and only one side is continuous, I'm also guessing that there's an issue with the pick-up coil or the circuit board

I don’t know if the continuous spark before the hole and rebuild. Not sure…

 

[Captjrhill]

I don’t know if the continuous spark before the hole and rebuild. Not sure…

Both sides are continuously firing. I did pull the second spark plug and see that it occurring on both sides.

 

[jpdevol]

I can imagine a problem, such as this, occurring if the engine or the ignition components do not have a good solid ground back to battery negative terminal (or an issue with a capacitor if used in place of a battery).

And the hole in the piston is a classic result of combustion occurring too early - perhaps from a spark at the wrong time.

 

[Jan_P]

Both sides are continuously firing. I did pull the second spark plug and see that it occurring on both sides.

That is normal for Boyer doing the same thing at the same time on both sides
Waste spark

I believe the problem is earlier in the signal chain that is why I suspect power supply ( Or ground ) as JP has it since Boyer is sensitive to that
Wrong Voltage and weird things happens

 

[mike in idaho]

It's usually a broken wire, or a dodgy connection. With the switch on, wiggle the wires & connections while you watch the plug gap for sparks. Pay extra attention to where the wires are attached to the trigger assembly.

 

[Jan_P]

I can mention that I use Boyer with stock alternator

As JP says in # 6
do not have a good solid ground back to battery negative terminal

At one time I was trying to Fault Find and at that time I pulled a Separate ground wire from the ignition all the way to the negative Terminal for testing.
I did not remove it and still have a separate ground wire .. Besides the other going to minus.

You might not have a battery but can then instead perhaps pull a separate ground wire to another place to get it To be sure it is solid. Ground