Reuse of a Crank with a Dislocated/Relocated Counterweight
I'm in the process of tearing down my engine to clean out all of the forbidden glitter that got around when I put a hole in the head of my piston.
I recently pulled the crank and when I got it out I noticed that one of the tungsten counterweights had displaced about a millimeter to the inside of the crank body. It was very close to hitting the connecting rod as the crank rotated. Before pulling the crank, I didn't notice any interference or grinding as I rotated it by hand.I've attached pictures of the crank and the weight in question.
I'm not sure when the dislocation happened - I didn't notice it before pulling the crank out but I also wasn't looking, and I did have the crank in the wrong orientation the first time I tried to tap it out with a drift.
I was able to…
Hey Robert, I will post it when I have it finished as my notes were very short hand bullet points for the tech session but to answer your question:
Basically I don't think CDI testing is reliable with basic tools and a multi-meter. The way I train it for technicians at my job is to basically test everything coming into the CDI from the stator and test everything after the CDI. If everything tests out on the stator side and everything between the cdi and the plug test fine, then it's the CDI. The CDI tests up and the dies. It can and will come back after it cools off enough to do it's job. Another tell is if you put a new plug in and it magically runs then dies a few blocks away, that's because the new plug offers less resistance since it's cold. As soon as it tests up and the resistance becomes too much for the cdi to overcome, it dies again. That's usually within a half a block. I use that as a tell but always advise verifying the stator with a multimeter before just slapping a new CDI in because nobody wants to push a bike home.
You verified the stator, it passed. The ground side of the stator was a problem on early casa kits as the anodized blue coating interfered with it's abilit to create a good ground between the stator and the engine case.
The only thing you could have done is unscrewed the plug wire and measured for continuity between the end of the wire that screws into the cdi and the terminal inside the plug cap but I'm not sure those wires even come out on those CDI's so you did everything you could to diagnose it.
Funny story, my brother's Vespa stator with an Indian K2 pickup coil dies while we were in Kentucky and I had to walk him through all the tests. We replaced it with an OEM piaggio pickup coil after I got back and it's back to being a 1 kick bike.
The only thing I still need to do is get photos of the tests. I'll roll one of mine on the bench in the next week or so and grab those. It'll be published in the specialist mag with a PDF download available here.