Modern Vespa

Hello
I have an 07 px200 and want to bridge the gap between 3rd and 4th and get a bit more top speed

The set up i have so far is
Malossi 210 with a mmw head
sip road race exhaust
24/24 with slide, polini filter/venturi, and drt float chamber
Uprated clutch

I can get around 7800 rpm in 3rd at around 94km per hr
as soon as i change to 4th gear the power drops and it takes a while to get speed up after

I guess i need a t5 4th gear?
Will an old T5 gear fit in the new px200 gearbox?
Should i change the clutch Cosa gear cog to make it longer?
Or should i change the Clutch and the primery gear cogs? ie mallosi primary kit

Any thoughts anyone

Thanks
Gary

Hi Gary

Are your engine and cylinder matched (ported/grinded/polished)?.

What jets are you using in your SI24/24 carb?.

Does it just feel powerless in 4.th or does it feel like it wants more fuel?.

Best Regards
Kasper

Hi again

On these covers, the supply hole from the float chamber to the main jet should be drilled out from 1.5mm to 1.8mm (PX177) or 2.0mm (PX200).

Try Read the following link:

http://www.sip-scootershop.com/en/products/float+chamber+cover+dellorto_128325t5

Best Regards
Kasper

What about a longer third gear?

Afaik, stock is 38 teeth.

This one has 37 teeth, and this one has 36 teeth


Looking at this gearing calculator it seems the extra tall third gear will let you shift from 7750 rpm in third to about 6000 rpms in 4th. If I'm reading that diagram correctly, standard third gear @ 7750 rpm will take you down to around 5700 rpms in 4th.

As yet no porting or matching has been done as the cases have not been split
I have drilled the float chamber hole out to 2 mm
And have been running between
145 and. 150 Main jet

If I were to put a longer third in I see the transfer between 3 rd and 4 will be easier but what about top speed?

Yes just a bit powerless in 4th at the start
I down't think it needs more fuel
At the moment it is one juicy MF
😜