Modern Vespa

Malossi 172 kit on a T5 with a cosa 20 tooth clutch. Do I change it to a 21,22 or 23. What do yous recommend please guys.

21 for sure, maybe 22…

I run a 67 primary on mine, I started with a 21, went to 22 and now I run a 23 for long trips…

I was going to order a 22 but I see a lot say they have a 21 in there's so I fort I'll ask on here. My primary is a 68 standard but I haven't checked but they guy I got it off said it's all standard

i have a 68 primary and with my 172 kit i'll switch back and forth between a 21 for short track racing and a 22 tooth for the longer tracks. I also have a very short 37 tooth 4th gear.

I suppose it all depends upon just how much torque your 172 produces. So that would definitely require installing a box exhaust.

I've got a TSR revolver exhaust to put on.

From what i understand, the Revolver is essentially a copy of the JL right. If that's the case, it will shift your power band up a higher RPM than a box exhaust. The second best way to make up for a loss of low RPM power is to either lower the gearing, or avoid riding into headwinds or up hills. The best way is to match your exhaust to your riding style...which is also matched to your cylinder (or cylinder kit).

My riding style has changed. In the past I would ride it like I have stole it but now as I'm getting older I'm more chilled out riding.

21 is the best compromise. 22 if you ride more open roads.