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@pattymcpatterson avatar
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2009 Stella DR177, 1966 Super
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Location: Madison, WI
 
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2009 Stella DR177, 1966 Super
Joined: UTC
Posts: 17
Location: Madison, WI
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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!
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Hooked
1960 Allstate VNA, 1962 VNB
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@fng avatar
1960 Allstate VNA, 1962 VNB
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Location: Cambria, CA
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Did you check your timing? Maybe the woodruff key sheared.
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Only time the kickback is like a mule is because of ignition timing (usually too advanced). When the spark goes off... its not because of high compression...

Then its a case of figuring out which part is broke... my bet is stator issue, or shifted stator plate...
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2009 Stella DR177, 1966 Super
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Location: Madison, WI
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Spinning the flywheel with a drill, the timing light is giving me 18° BTDC. Hm. Was honestly expecting it to be seriously advanced.

Even with a possible +/- 2° error from my paper timing wheel, it should still run at least, right?

Thanks for the replies, folks. Gotta go pickup a flywheel holder now, take a peak at the stator and woodruff key next.
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PattyMcPatterson wrote:
Spinning the flywheel with a drill, the timing light is giving me 18° BTDC. Hm. Was honestly expecting it to be seriously advanced.

Even with a possible +/- 2° error from my paper timing wheel, it should still run at least, right?

Thanks for the replies, folks. Gotta go pickup a flywheel holder now, take a peak at the stator and woodruff key next.
Yeah that’s a little weird… I found kick back around 23-24 degrees (for a 18degrees kit) or something around 30 degrees (trust me… someone set it at that timing…)
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2009 Stella DR177, 1966 Super
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Location: Madison, WI
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Tested with a new spark plug just to be safe. No dice.

Moved on and pulled off the flywheel today. Woodruff key is all clean and intact.
Nothing obviously wrong with the stator.
However I did have some engine oil pooled in the case under the flywheel and a film on the bottom of the stator. Maybe the flyside seal has a bit of a leak then. No idea how that would contribute to the problem though.

So I'm on to electrical tests. I have a new CDI to plug in if need be. I also saw a step-through with an ohmmeter somewhere on this forum, checking connections at the CDI. I know my kill switch stopped working a year ago so checking electrical from the ground up couldn't hurt.
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PattyMcPatterson wrote:
Tested with a new spark plug just to be safe. No dice.

Moved on and pulled off the flywheel today. Woodruff key is all clean and intact.
Nothing obviously wrong with the stator.
However I did have some engine oil pooled in the case under the flywheel and a film on the bottom of the stator. Maybe the flyside seal has a bit of a leak then. No idea how that would contribute to the problem though.

So I'm on to electrical tests. I have a new CDI to plug in if need be. I also saw a step-through with an ohmmeter somewhere on this forum, checking connections at the CDI. I know my kill switch stopped working a year ago so checking electrical from the ground up couldn't hurt.
I'm sure the leak is unrelated.

I had a leak too behind the flywheel.. thought it wouldve been behind the primary drive shaft (which I usually use sealant as a precaution, which i thought might have failed) but it actually ended up being the crankcase bolts in that area had loosened after initial torquing to spec.

Ended up re-torquing and the leak disappeared.

Not have a spare stator? just so you can eliminate that being a problem too.
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1978 P150X; 1982 P200e
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I am eager to see what you find. I have been fighting a kickback issue for years. I even replaced the stator & flywheel for a flytech but issue persists.
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2009 Stella DR177, 1966 Super
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Posts: 17
Location: Madison, WI
 
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@pattymcpatterson avatar
2009 Stella DR177, 1966 Super
Joined: UTC
Posts: 17
Location: Madison, WI
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Electrical testing today while being eaten by mosquitos. I like Madison WI but honestly it is a midwestern swamp.

Testing ignition coils at the stator junction box:
White to red: 112 ohms
White to green: 527 ohms

Testing white to green over at the CDI however, white to green read between 1 and 12 ohms. Now I have an issue with my kill switch not working so I figured there is something there. I might have other wiring issues to deal with later.

However, stator is good. thank goodness as I don't have a spare.

I did have a spare CDI and figured why not try that.

(And then discovered what a headache it is to access the bolts for the CDI on a Stella. You'd need to pull out all the other bits, rectifier etc to reattach it the same way as the nuts are hiding behind all the stuff. Big fingers. Nope. Inverted the nut/bolt and skirted that issue.)

Buttoned everything back up, set all the grounds and tried to kick it over. My stomach sank. Kickstart was completely locked up.

*** removes flywheel holder *** Facepalm emoticon

Kickstart again and it fired right up!!! It was the CDI. I feel like I got really lucky here. I hoped CDI, bought a new CDI and it was the CDI.



I've never seen diagnostics available for a CDI, but does anyone have any idea what can fail in these abusive little boxes? For closure, I just want to know what was going wrong. Maybe the charge was being dumped every nth revolution, maybe charge dumping erratically. Maybe I had just enough spark for occasional hits on the timing light since my timing looked fine.

in any case I'll report back in a week if the replacement holds up.
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2009 Stella DR177, 1966 Super
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Posts: 17
Location: Madison, WI
 
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2009 Stella DR177, 1966 Super
Joined: UTC
Posts: 17
Location: Madison, WI
UTC quote
No issues with the new CDI after a week of riding. Think I can safely say the kickstart kickback was resolved with a new CDI.
@fng avatar
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Hooked
1960 Allstate VNA, 1962 VNB
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Posts: 271
Location: Cambria, CA
 
Hooked
@fng avatar
1960 Allstate VNA, 1962 VNB
Joined: UTC
Posts: 271
Location: Cambria, CA
UTC quote
PattyMcPatterson wrote:
No issues with the new CDI after a week of riding. Think I can safely say the kickstart kickback was resolved with a new CDI.
That’s great.
Now I know another thing to check if my scoot starts kicking back.
Happy riding.
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