Welcome to the Vespa Club of Britain forum, Hosts for Vespa World Days 2012

my wife recently bought a 1991 Vespa "V" PK 50 (uprated to 80) as her first bike low weight bike with handlebar gearshift. Now realises that too slow for majority of scooter runs and would like upgraded to 125-135cc which I think is possible. I guess that when starting from a 50cc engine that crank, shaft, gearing, clutch as well as top end will all need to get upgraded to get to reasonable speed level. Firstly is this possible? What pitfalls should I be aware of? What is the likelyhood of me getting hold of a smallframe 125cc engine toi suit through sechand route? Any advice gratefully rec'd. Thanks

The main thing is the crank needs changing to a 51mm stroke, this will allow you to fit any 125cc top end, or any of the 135 kits available. The gearing will need changing as well.
Join the smallframes forum for more advice, top people, they'll be able to help you more!
http://davedaniel.proboards.com/index.cgi?

Its a swing and roundabout type of qusetion, yse its poss to chnage the crank and up grade the barrel but buying a complet lump me be easier but there not that easy to come by nowadays.

You will need a new crank- up gear kit -clutch - 50 gearbox is the same as 125 ratio wise so thats ok - barrel - carb - exhaust - with the smallies you have so many options it can become a mine field.

I'm pissed and can't be arsed posting here BTH, will next week if I can be bothered. Other than that drop in past the smallie forum and I might before the weekend's out.