Not firing on left cylinder CB72

[OldScrambler]

Occasionally one set of points may not be properly grounded. Although there is spark, it is so weak that the wet plug will not fire. With the motor running hold a screwdriver tip to the #1 points as they break and listen for any improvement. The solution is then to replace that set of points.

[ramwing7]

Welp. A new coil got the spark back on the left side. Idles like a little sewing machine.

Unfortunately, it still refuses to run smoothly under acceleration. Pops and carries on when it's under acceleration load.

Back to the carb, I guess. Needles are gonna go up and down to see what happens.

[HondaPaul]

Hi Dennis,

Just curious what the screwdriver tip close to the points does? I mean what is the theory behind it? I, too am having issues with the left cylinder. The first time I had it running (new rebuild), the left cylinder would misfire out of the carb and exhaust when giving it throttle. I rechecked the timing and found the left points opening late. I re-adjusted and re-cleaned the points and now the left side is not firing at all. I can remove the sparkplug wire while it is running with no difference in the idle.

I plan on trying a couple of things like swap the coils. Your idea sounds quick and easy, I just want to understand the reasoning behind it.

Thanks
Paul

Occasionally one set of points may not be properly grounded. Although there is spark, it is so weak that the wet plug will not fire. With the motor running hold a screwdriver tip to the #1 points as they break and listen for any improvement. The solution is then to replace that set of points.

[HondaPaul]

Never mind. It was a fuel related problem, left carb wasn't getting fuel. Runs great now!

Paul

[Director]

Honda Paul - so what did you do to the left carb to make the left side run properly?????
I'm having the same problem.