Betty Gets a New Piston

Happy to report more progress has been made! I started today by first deciding today would be the day that I got those circlips out. Reminder, this is what those look like:


It’s that little circular clip thing in the middle of the piston. After trying with pliers few more times, I asked Brendan to try and he couldn’t do it so I said, “ugh fine” and went to Home Depot to buy the proper tool. They only had one kind and it was $30 and I’ll likely never use it again but whatever, I bought it and used it and IT WORKED!

Sometimes I guess it’s worth it to buy the right tool for a job. Even with the proper tool, it was really hard to remove. When I finally got it out I literally said out loud to myself, “ahh yessss”. I will also note that it felt weirdly similar to playing the game “Operation”.

The next part of the task was to push a pin out through the piston. Here is a picture of what is going on in there:


You have to push the gudgeon pin through the connecting rod in order to slide the piston off. So with one circlip out, I flipped it over and took a flat head screwdriver and tried pushing the gudgeon pin out while supporting the piston with my other hand. I did get it to move a bit, but it didn’t seem to want to budge after that. I called Brendan in and he held the piston and screwdriver, while I hit the end of the screwdriver with a hammer to get it out. This was absolutely a 2 person task. After lots of hammering and positioning, we got it!

As you can see, the piston is pretty scratched up. I’m told that this is due to seizing, which makes me worried that that might happen again? Guess I’ll have to go look into what causes an engine to seize…

Anyway, I brought in the piston (and accessories), cylinder barrel, and cylinder head into Vespa Motorsport today since I learned they actually are open Saturday afternoons. Kevin was there to greet me again and told me I’d need a new piston and the cylinder was in pretty good shape, but they’d still rebore it to make sure the new piston fit properly. They’re also going to help me smooth out the cylinder head. So I left the cylinder barrel and head there and took my junk piston home, and my new/improved parts should be done later this week. I can’t wait to see what kind of compression I get after this. Lastly, I bought myself this little figurine because it’s cute and I like cute things:


It’s not the same model as Betty but it was as close as I could get.While I wait for her new parts I think it’s time to do some cleaning!



1 thought on “Betty Gets a New Piston”

  1. Now this IS exciting progress!
    Everything up to this point has been equally important, it feels like crossing a threshold!
    At this rate, you’ll be riding it by the time I come through town on the 9th (honestly, let me know if I should come by in the afternoon).
    I’m thinking that these are two-stroke, air-cooled and splash lubricated– not that I’ve read anything about them, just from looking at your pictures– if, so, there are no valves, oil pump or cooling systems. The air-cooled engine usually needs to either be ridden for temperature management by radiating via cooling fins or a crank mounted fan (is there one on the clutch?). Air-cooled engines shouldn’t be run under load without air flow or being ridden for very many minutes at a time; Kevin should be a great source of information and guidance.


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