Vespa 50 FL/HP tuning

Hi, I’m looking at buying a 1992 Vespa 50. It is a PK style smallframe and I think it is either an FL or a HP.
But I am concerned that it will not have the power needed for the daily comute to work.

What would be the optimum set up that I could get from the bike with the minimum amount of work?

Also, someone told me that they think these 50s are restricted via the gearbox, would I need to up rate the gears?


the minimum amount of work would be to change for a ki75cc.
you could go higher in cc, but at that point you have to upgear.

What kind of top speed might you expect from the 75cc option?
and would the carb need modifying?

I noticed the scoot already has a Polini exhaust on it.
I’m only considering buying the scoot at the moment as it is cheap.
But as I also think the headset on the HP is quite ugly and would probably want to change that also, I’m thinking that to put a 100+ kit on and uprating the gearing and carb might be a bit more work than I want to deal with.

Personally I’d go with a 100cc+ kit,up-gear,pipe and bigger carb.

50’s are ludicrously low geared and you will almost certainley blow it up if you don’t lenghten the primary.

Thanks for all the advice.
I think I’ll have to give it some thought before I plunge straight in.


I agree with Juank.
If you modify your engine is better to go on a 100 cc kit otherwise I would buy a 125. I own a 125 xl with a personally tuned engine but I must admit that the original is a good and reliable engine with enough power to bring you wherever you want. The 75 cc option suggested by Curare is also a good choice if you really not want to do a great deal of work.

Without upgearing your Vespa will reach approximately 70 Km/h. Fl and Xl 50 cc models are really restricted with 14/69 cogs. The change of the primary gear with a Pinasco 16 cogs helps very much. It is adviceable to use a 16/16 carb.

The change of the headset will take a long time. I fitted a XL headset on a Fl recently and the work is not difficult but require a good knowledge of mechanincs and electrics.