Hi everyone, long-time lurker, first time poster. Completed my first rebuild this past winter on an old mystery P engine thanks to all the nice posts here so I'm documenting an investigation hoping this helps someone else out.
The scoot in question is a 2009 Stella 2T rebuilt in 2018 professionally with a new crank and DR177 top end. Been running fine ever since as a daily commuter. Thousands of miles on it with the current setup.
The other day the engine slowed and died while idling. Managed to start it with the electric starter, after some effort. Made it home, but dead again once it came down to idle.
Assuming the idle jet was clogged I checked the carb and blew everything out. No blockages. Tried to start up again, but then a new symptom: Kickstart with Kickback
Break your ankle kind of kickback. It didn't feel like metal and taking the kicks real slow I managed to cause a backfire. The electric start will come to a clanking halt if I tried to turn it over too many times. Hasn't started since.
Read through a few threads and saw this issue before. After homework I have checked these cases:
- pulled the clutch lever - kicks over fine, no issue with kickstart or x-mas gears
- pulled the spark plug out - kicks over fine, piston isn't seized
- ignition off with spark plug in, kicks over fine again. Not some high compression issue.
- ignition on, NOPE. Kickback from the kickstart only happens when I have spark.
I haven't completely drained the carb bowl so even with my fuel tap off I'm guessing the spark is firing too soon and causing some early detonation. That pressure is turning the piston back and all that force makes its way through the gears back into my foot. Never even touched the stator or timing so something musta broke.
Any thoughts on what could've broke from the crowd?
I initially thought clutch shenanigans, but I think it has to be spark related now. I'm guessing the culprit has to be one of these:
- Stator issue, wires cracking or timing got bunged up
- CDI
- high tension coil
Anyone have advice on a good order for checks/ replacements/ how to diagnose this?
I'll start with the static timing. See where's that at then pull the flywheel.
Thanks!