I've decided to stop busting @Jim van Morrisey's and taking this discussion to a wider audience than our chat. Thanks for the help so far Sean!
I have a PX200e since a couple of years ago and I've been restoring it stock. It is important to mention I live in Quito, Ecuador (2,800m above sea level). This is my 3rd Vespa. I'll share some photos of the other ones later. (PX150e & VBC)
I installed a 2nd or 3rd OS Meteor piston (Scooter Center) to address 'lack of compression' from the previous one. At first I didn't realize the bike had a 94 main jet and one of the idle jets with the solid top. The bike had a very hard time going uphill, and it seemed to soft seize/stall in urban uphills.
I chatted with @jimvanmorrisey and followed his advice to install a 160/55 idle and a 110 main. (160/BE3/110~).
~. However, the local mechanic had to fit a small copper filament from a wire to make it somewhat smaller, as it was bogging BIG TIME and with flooding symptoms all over the place without it. It is not easy to find jets here so that is the local fix to make them smaller. Still larger than the previous 94. The bike is much more awake and powerful in flat rides and does small urban uphills in 3rd just fine. I was confident enough to try a longer ride today (1 hour, 300m altitude change) and things were fine flat and downhill. I checked the spark plug and saw the chocolate color for the first time (photo below) so I decided to keep going.
I had a couple of soft seizes that I controlled with a fast clutch action when going almost WOT or WOT in 3rd for a small period. 4th gear seems not as powerful but I think this may be because im still running in the new piston.
After a 30 minute stop at the lowest point of the ride, in the city suburbs, we took a faster road uphill and the bike seemed to struggle in 3rd and 4th gear,
or not be as powerful. As if it doesn't 'develop', we say here. Running in period?
The big issue came again when heading uphill towards the city. The bike stalled/soft seized at least 4 times and I was getting anxious. Clutch saved me every time! I saw the spark plug half way uphill and it seemed whiter than before, but not too much. still pretty chocolate. However, it was VERY HOT to the touch. I opened the mixture screw half a turn out of instinct, and managed to get the bike back up into the city after at least a couple more stalls/soft-what-nots.
Please share your thoughts! I've spent hours reading Aviator's posts and others I don't remember the names now but I've finally decided to ask for specific help!!! I'll be splitting that top end this week to see how is that piston doing. Probably check the rotary valve with a feeler too.
PS, let me invite you to the Vespa Southamerican Days in Quito on Nov. 25-27 2022. Let's ride along the half of the world or Mitad del Mundo!
Spark before going uphill. Bike running great on flats and downhill
I'm calling it The Lucky One over here. I'll tell you the story🍀