Usually a weak spark shows up under acceleration, where the engine is put under a load. I have seen a couple of cases where the headlight switch was ON and that was enough to make the engine hard to start.

Ride on
Brewstser

 

Update:

I pulled the carb off again to check the air jet. It is a 1.0. No surprise.

I measured the float height but am unsure about the proper measurement procedure.
With the carb inverted and the float resting lightly on the valve, it is slightly angled upward and measures 19mm from the carb body at the highest point.
With the float depressed to take up the spring slack, it rests level (parallel to the bowl flange surface) and its height is 15.5mm, IIRC.

I spoke to my mechanic friend at length last week and he pointed out that a 20-y/o magneto/generator is likely weak and will cause a very weak spark during slow engine rotation (kickstarting) but will generate good spark during faster rotation, such as push starting. I had to agree with him and ordered a new stator. Supposedly Made in USA with pride (in CA). Got scammed by dang Commiefornians because they sent me a Chinese part for 1/3rd of the price. And they pocketed my $100. I hate scammers.
Nonetheless, the new stator did not improve the situation.

Somehow, I did manage to get her started again and she was blowing the usual amounts of smoke on the choke circuit. After closing the choke circuit, the smoke went away and she idled nicely.
Upon shutdown, she would not restart again.

I don't think I mentioned before that sometimes when kicking her over, she kicks back. Not often but she does. Timing too advanced? There is no way to adjust it since the pickup coil bolts down hard. CDI unit faulty, advancing too soon? *shrug*

I pulled the plug out today and put a compression tester on the head. Specs call for 64-127psi warm, IIRC. I kicked her over 3 times and got 115psi cold. Well within spec.
Also checked spark on the plug: bright blue-ish white. (hard to tell while kicking at the same time)

Now my mechanic says that since she smokes at startup, my rings are gone, my compression is low and I need a top end overhaul. Though the compression numbers do not support that theory.
However, I will pull the head anyway to inspect the valves. That smoke keeps bothering me.

Any suggestions? Advice? Questions?

 

What color smoke? What's it smell like? Blue is oil and will have a different smell than gas. Grey (white?) rich gas mix, possibly due to the enrichening from the choke and smells different from oil. Bad rings would smoke more than just on start up. Just some thoughts.

 

Valve seals?

 

Smoke is grey-ish blue or blue-ish grey, hard to tell. Smells bad but that's as far as I can tell. I am not good with smells.

Pulled the head today and found all valves dry with no oil leakage from the top. The exhaust port is pretty oily.
Went deeper and found the cylinder bore nice and shiny, aka glazed. Time for a quick hone job.

 

Smoking on acceleration (under load) is usually rings. Smoking on deceleration is usually intake valve seals.
The stator is just wires, nothing to "get old". You wasted money on that one.

Ride on
Brewster

 

Yup, she smokes a little on acceleration but a lot more while warming up with the choke on.
I agree that the stator is just wires and doesn't normally get old but old insulation breaks down, causing small shorts in the coil windings, weakening the output and thus making the part under-perform. I have re-wound a lot of coils in my younger days. Getting too old of that now.
So it was not unreasonable to replace the stator. I didn't really mind that much. I minded being scammed by Californians.

Nonetheless, ordering new rings and other parts today, hoping to have her back together by next weekend. And hoping that she will actually start this time. (not holding my breath, the cylinder sure needed some honing but I gotta humor the bike)

I will post another update in a week or so.
And if she still doesn't start easy, I will be probably begging to borrow a known good CDI and spark plug coil. I really don't want to blow $300 for a simple test.

Thanks for all the advice, y'all.
Lou

 

Update:
Finally got parts in (took a whole week to ship a few hundred miles, LOL)
So the honed cylinder and new rings with proper gaps mean no more smoke on startup.
However, I still can hardly start her when cold. It is a workout.
When warm, she started 3 times decently quickly. But the 4th time, she did not want to. I gave up.

When she was warm, she "wanted to" start multiple times but did not. Often kicked back or popped into the exhaust. Timing too advanced?
Should I try to beg someone to borrow their CDI to try out? I am running out of ideas.