Vespa 21t clutch cog

[Jack221]

Johnny, I think of the DRT 22 tooth as the straight cut Cosa one. The 22 Cosa cog is mine is a Piaggio one from a PX150. Next time I split the engine I think I'll put in a T5 4th, like yours. The extra rpm in top will get me a bit higher up the power curve for a few more mph.
Whats the rest of your set up? Need any help with a bit more power?

[johnny rotten]

I was persistant n managed to find the 22 tooth clutch drive plate eventually. As for the remainin spec the top end is a Harry Barlow 57mm gas flow crank with his 207 stage 4 kit...Std 24/24 carb with cosa bowl n needle std pilot jet, 132 main jet be3 atomiser 150 air corrector, std air filter with 4mm hole over the main jet...timing is set to about 25°btdc at the moment as I've just fitted a chiselspeed mtech adv ret box...also the starter motor n flywheel ring gears been removed...t5 fourth...sip2 rd pipe. Its probably not the fittest p2 about but I'm quite pleased with it now it can do the clock when conditions are right which is something imo as I'm 20+ stone...I'm not sure how I could increase the power without porting which I don't want to do as I want to leave it std ish...unless you can make any suggestions?

[Jack221]

The key to a good set up is how it all the important parts fit together. When you are looking for maximum performance you start to realise that a crank isn't exactly 57.00mm, a conrod isn't exactly 110.00mm, Piston compression heights can vary by 0.1mm. And on the road this makes a lot of difference to engine performance. Even on standard engines, one will go better than another and this is a big part of the reason why.
Did HB assemble your whole engine or did you just buy the bits from him?

[johnny rotten]

I purchased the parts from him n done the work myself

[Jack221]

In that case there is almost certainly some fiddling that can be done Are you planning to take the cylinder head off anytime soon?

[johnny rotten]

Whats yer idea involve Jack because the head on this set up is recessed to fit into the top of the barrel unlike std where it sits on top of the barrel?

[Jack221]

Am I right you are running a Polini 207 barrel? Or one of HBs heavily modified standard P2 barrels?

[johnny rotten]

Its the modified std p2 barrel

[Jack221]

I have a tuned standard barrel with a grand sport piston on my other PX. I set it up for crusing. Really pleased with it.

Did he give you any special instructions how to set it up or non standard gaskets to use?

[johnny rotten]

Quite straight just had to do dremel the back edge of the carb inlet by 9mm n match the casing to the barrel n set ignition on the IT mark approx 18°btdc also there's a packer plate to raise the barrel that's about it