Cosa 20 tooth clutch


        Ive just joined here after i was given a link from scooter boys world, ive got a question about cosa 20 teeth clutches, what are the pros and cons of it being 20 tooth, ie will it match my p200e engine ok, also will it gear it up or down, thanks

p.s the engine its to go in is a 81 p200e engine that im building using bits ive got lying around and that im buying cheap off ebay etc.

so far ive got an old autisa aluminum barrel kit(for standard p2 piston but the previous owner left the gudgeon pin circlip off so i need to use an upsized one)

a malossi reed valve manifold (thanks for the thread on mods needed to fit it)

ill probably use a scootrs pipe and one of their keihin pattern carbs.

any advice on crankshaft mods that will help the reed valve setup work better would be appreciated too.


hello ultraphine,

no much experience with this kit and was long time ago…yes I am that old…
You could tell us how you will like it.
… hope you are going to quickly understand the sense of humor of our friend Mikkke.

G o d as Good old demon or Grace of dawn or some other even more criptic Indian meaning…

Welcome here ultraphine,

You can follow all what Curare’s he is our G o d.


Yeah i guessed that,

Ive been reading his posts, seems like he knows the score.

Um curare, do u know much about the autisa barrel i mentioned?

Its aluminum with the same port layout as standard, but an enlarged inlet, bridged exhaust and the transfers larger as well. i bought it about 10-12 yrs ago for ten bucks

hello and welcome,

no 20 teeth with P200 gear. In the 200 you have a christmas three ( input shaft) with a primary of 65 teeth and this is not compatible with the 20 teeth.
The shorter you can use is the 21 Cosa, but better for your set up will be using a 22 (I saw SIP selling them) or the 23.

The Cosa clutch is a better clutch for me then the older vespa ones. It has les slip problems, and even with the use of stronger spring the pressure on the clutch handle is confortable and smooth, not so with the older design where the use of strong spring make them pretty hard to action.

Some older cranckcases has to be slighly modify to be able to use the Cosa clutch. But is a simple dremmel work that takes no more then 5min.

For your set up you could use either a normal cranckshaft or a Mazzucchelli race one, of course if you have opened the inlet port as it should have done.
The use of special lip crank is advisable just in engine that likes to rev high.

For the Malossi reed block if I understood you have already seen my picture in this forum. Check it well one step at the time before mounting it.

well im starting to feel old too LOL 33yo here.
Seeing as you are in italy from what i can gather, you wouldnt happen to know of a vespa gl frame and panels going would you? Ive got a mint reco’d engine /forks and headset sitting here not getting any use and id love to have a gl frame to put it in.

Cheers mate