I want to share my small project with you and ask for some hints. I found in my garage one S50 2T tuned to 70 with engine dying. I was just ready to fix it, when I found rusted and ugly S125 4T for really few coins.
Changing the engine was on my mind since some time, but I was not sure about wiring, CDI and other components, so I decided to look for a complete Vespa. I was hunting for 125 ie, but it's quite impossible to find one cheap.
What are the differences?
1) Wiring. 4T engine has differences there and looking about both I think it wouldn't be such easy to convert that. The CDI is also different, but I believe you donít need the key or locks.
2) Fuel system. On 2T is completely different, and the fuel tank is bigger (no oil tank for 2T on right side).
3) Gas cable and rear brake cable.
As this was a straight forward swap and S50 was scratched a little, I decided to paint the body before reassembling. Tried to invent some crazy colour, but wife unfortunately made a clause: original fire red or nothing. Finished with glossy for deep colour effect, still not polished yet.