I have asked this question of others, and gotten some good answers, which I deeply appreciate, but none that really seem to "click." I figured I'd try it here as well to see whether I could collect any more grist for my slow-grinding brain...
My 160 GS is dead stock, has 26,000km, and sat in a dry barn for the past 15 years or so.
I've gone through it, had the cylinder off, found the rings were clean, combustion chamber in good condition, and wear minimal.
I filed the points, but did not replace them because they looked better than the replacements and had perfect continuity. It has a new condenser, there is no points sparking when running. I carry the old condenser (there has been some condenser swapping back and forth while troubleshooting at different points).
I rebuilt the carb. - new float, needle, gaskets, all cleaned and blown through.
The fuel tank was sloshed and recoated years ago. New fuel tap. No problems with the tank lining peeling.
New black rubber fuel line.
I cleaned the original muffler with Drano, then left it to cook on the charcoal grille.
I replaced all cables. All are working well, no binding.
New plug (B6ES, if I remember).
I resealed the original coil into the original can, on the advice of Gene from S.O.
All rubber parts and the spark plug wire were replaced.
Gas tank was full, mixed 2 1/2 gallons to 16 oz of generic 2-cycle oil.
It's a Euro battery bike - all electrics working well. All contacts have been cleaned with Dremel wire brush attachment, including inside of headlight / ignition switch.
6v / 12ah maint. free lead-acid burglar alarm battery.
The bike had been starting 1-2 kicks over the past 2 months.
A few days ago, I turned on the fuel, pulled the choke, 2 kicks, started right up after about a week not running.
I rode about ten miles, at average 40-50mph, at an ambient temp of about 80 deg F.
I turned off the bike. I think I did NOT turn off the fuel
After about 10 minutes, I tried to start it - nothing. Maybe an almost-pop once or twice.
I kept trying to start - choke on , choke off, throttle open, throttle closed. Repeat.
I started taking stuff apart - changed plugs back and forth, checked spark [good], moved fuel tap to R, pulled and pushed on fuel line through body. Plugs were getting wet.
I pulled the air cleaner, found good fuel spray on kick.
I tried starting fluid (ouch) - nothing.
I pulled the flywheel to check for a sheared key - perfectly fine, all electrical connections good, no sparking at points when kicked, still a good spark at the plug.
A thunderstorm started. Everything got soaked, including me.
I put all back together.
I turned the ignition switch on, put the fuel valve to Run, choke off, gave a kick, instant start, smooth idle.
I rode home in the rain, no problems.
So, why, after months of running great, did it decide not to start for that one time, and then behave perfectly well again afterwards?
I can categorize them as follows, within my own framework:
Possible problems with any motor -
-- Compression - N/A here
-- Timing - Checked, hadn't changed, N/A here
-- Electrical - Spark looked identical throughout this experience, and the same as it always had before. This s not conclusive evidence that all was fine, but it sure looked okay.
----Within Electrical: Coil heat intermittent, Condenser heat intermittent
----Discounted within electrical - leakage from wire or plug cap, bad plug, bad primary wiring.
-- Fuel - Vapor lock or flooding.
I saw normal-appearing spray from the spigot in the carb while kicking and the plugs DID get wet, making fuel starvation seem unlikely.
No improvement after I put in a new plug, making flooding seem unlikely.
Well, does this ring a bell for anyone?
Or is it just a "quirk" I'll have to get used to dealing with now and then?
Thanks,
- Eric