Modern Vespa

Hi! I have a 221 malossi with rotary valve 60mm bgm crancshaft on my px. Has anyone tried to convert a 60 crank to 62 with this pin?
https://www.sip-scootershop.com/en/products/crankshaft+pin+drt+eccentric_4043ad179a
I have a good mechanic who is able to do the job, but has anyone tried to do it and has any tips for the job?for sure i think i would need to convert it also to reed,although with the rotary now works just fine, but to be frank, ive never driven a reed vespa..scooter center told me that this crank will work fine with the reed valve, but why are there different cranks to buy for each case?

Scooter and Service use that pin for their 62mm cranks.

https://www.scooter-and-service.de/shop/vespa-shop/engine-parts/crankshafts/54/crankshaft-s-s-long-stroke-reed-valve-px-125-px-200?number=SS0321&c=902

You may be better off with someone who rebuilds cranks because it will need to be done to spec and probably re-balanced. But your guy may be able to do that.

A rotary crank has a built in imbalance because it's cut away in certain spots. It also creates a small amount of friction as it (just) touches the opening. The balancing that's been applied to that crank may not suit the weight of your piston.
A perfect reed crank doesn't get in the way of the gas flow, and that's why the bell shape was developed. That and balance, along with lower crankcase volume (which is a subject for another day).

why do you want the realize 62mm stroke?

on simple 60mm stroke the sport is good for 26-28hp at the wheel with rotary valve, with reedvalve probably more, just do FINE tuning
cylinder and intake timings, exhaust port shape and width and a proper exhaust

no need for different stroke and all that effort

for more power you need to switch to the M244 only a bit more stroke wont help

+1 Not worth the effort.

If you're wanting more speed, then you need no more than the 60mm. The longer the stroke, the less rpm the conrod can take. And we like rpm.

As FMP said, the tuning of the ports (size, timing, shape, angle etc) is where the power is hiding.