Modern Vespa

Thank you, again MVF members… If it wasn't for you all, I'd be lost.

1. My concern with replacing the base gasket is not the $10 cost (in fact, I already have the gasket), it's the skill level involved. While for some, it might be an easy few minutes with the piston rings staying in nice and cozy, I'll no doubt muck it up…. The piston will drop out of my big, clumsy paws and the rings will end up scattered on the garage floor. So far, I've managed to get the engine out with only breaking the coolant temperature sensor electrical attachment clip, so I'm not going to tempt fate by removing the base gasket unless the engine is going to explode without me doing so. This brings me to another question:

4. As mention above, my giant fingers got impatient with the coolant temperature sensor . See pic for result and then say to yourself, Yeah, this guy probably shouldn't do the base gasket. In any event, this end of the connection doesn't look easily replaceable. Upon reassembly, should I get creative with electrical tape to keep it all together?

Not sure what it is exactly that you want me to show you, but it worked fine on my BV350 (and many other top ends I had apart over the years). I did ultimately remove the piston, but it was more my curiosity about the condition/measurements of the bore. When I put it back together. I installed the piston in the cylinder, pushed the piston down until the pin boss was exposed, and installed it as an assembly. Easy peasy.

When I worked for Harley the only engines in which we didn't automatically replace base gaskets when removing a head was the twin cam (and later) engines. We still recommended it, but it wasn't necessary because they use a cylinder base O-ring, which can be squashed again and will usually seal up without issue. Also if note, there was only oil passages since they were air cooled.