Modern Vespa

So I've run through a few little projects on the ol' Sprint since I last updated this thread. I put my Stella motor in the bike, which is a decision I have not regretted, and blew up the piston when I had it on the Stella motor and the crank failed.

So I had to replace the piston. Today, I transferred the old porting via a rubbed paper port map over onto the new piston and set to work with the trusty ol' Dremel.

Things went quickly and smoothly and I was able to fit the new piston and check port timings this evening. Timings came in just a smidgin lower than previously, like 123 vs. 124 on the transfers, but that could also be measurement error since I more verifying than measuring several times and averaging.

Squish is also high with the new head, so I'll be spending some quality time with the wet-dry paper and glass to shave it down, maybe this weekend.

Once the motor is back together, it'll go in my Stella frame for a bit, and then probably transfer over to the GL once I've got that frame into working shape. I'm still thinking that a hot P200 motor might be what ultimately winds up in it, though.

The other project I pulled together was fabbing a new CHT bracket and adding a night light to it. We're heading into the Dark Season, when the only time I'll see the sun is on weekends and if I got out for lunch during the week. This means that I mostly ride at night, and I like to be able to see my CHT, even if only to know how warm the motor is NOT.

So I found an instrument panel light for ultralights which is fully waterproof and gives me two red LED's. It has an M6 thread on it, so it was a pretty straightforward mounting process. I ran the wires into the headset and piggy-backed them onto the four-position switch.

The only thing I don't like about it is that the light is really too low, so it throws a lot of light (and with it, glare) onto the edge of the CHT case. I'm going to do a Version 2.0 which bends a raised tab for the light so that it sits higher and maybe angled down, but I'm operational at least.

The other thing I did while I was doing was install a 12v-to-3v DC converter to power the Coso CHT. It uses CR2032 coin batteries, which wouldn't be terrible if they didn't have to be replaced every couple of weeks.

So I wired the converter in to replace the battery, ran that into the headset as well, so I'll never change the battery on that thing again. The one mistake I made, in hindsight, was to not leave the CHT powered all the time. When it wakes up, it always defaults back to Celsius, which would be fine if I thought in Celsius, but since I think in Fahrenheit, that's a problem for me. It's just a matter of switching which blade on the switch I piggy back off of, but I just don't want to pull the headlight to do it right now.

At this point, the headset is pretty much FULL of electrics, but I'm not sure what else I would stuff in there next, so I guess that's OK for now.

I can see why the paper piston didn't work out for you - much too low compression!
Is that a Grand Sport replacement?

Low compression, but the porting work was the easiest I've ever done!

No, I couldn't find a non-oversized Grand Sport, so I'm stuck with 2mm rings again.