Modern Vespa

Hi guys, im building a vespa VBB2 and am currently building a vmc crono 187cc engine for it. So far ive got all the parts, custom reed valve crank case, vforce 3 reed valve, 30mm smart carb, sip ignition.
But the one thing I dont have yet is a crank shaft and con rod since vmc discontinued theirs. And im new to engine building so I dont really understand cranks all i know is i need a 60 stroke but I don't know the difference between full circle, bell shape and all the other shapes.

Someone out there please enlighten me on what crank I need haha

that exhaust is very cool!

Hella cool!


edit: read underneath it.

Thank you, its an indonesian local made exhaust, but it doesnt work well with my slightly tuned 150cc excel block, thats why im going for the vmc upgrade.

Depends on the crankcase. I assume that custom crankcase is from PX series (PX, exclusive, excel) right? if not then the crankshaft options is very limited due to different bearing and seals position on older crankcase.

Update for people who may need the info. All came together well, had some issues with all the customisations to the crank case, ie surfaces not completely flat on the built up section for the reed valves and other small leaks. I ended up using a sip crank with 60 stroke paired with a sip race clutch 23 teeth, to anyone looking out to get a sip clutch they comw with 6 light springs only so i added 3 heavy race springs as the clutch feel was too light but saying that i am also using crimaz pressure plate and push rod that improves the clutch feel immensely. The VMC crono 187 feels amazing, at first i was running 0.8 squish instead of the reccomended 1.3 but after seeing reviews of overheating and piston failures i decided to raise it to 1.5 since this will be a touring bike. Dyno test coming up but our estimation is around 30hp we could push for more if we decide to port the block.
But i think for now thats enough since 1st and 2nd gear its impossible to get the front wheel to stay on the ground ahhahaha.
Anyways full specs are
- VMC crono 187
- modified crank for reed valve
- vforce 3 reeds
- gear ratio 1-3 strada 4th gear close ratio
- sip 60 stroke crank
- sip race clutch
- 32mm nibbi racing carb
- sip vape ignition
- drc ffa exhaust (local made indonesian)

We demand more pictures and video of this scooter

I got youhttps://youtube.com/shorts/ePqoQRjvYJs?si=YS6Tn99cRNoeBpmi

Sounds healthy!

Nice build, sounds good. congrats. Could You share your jetting setup please. Main jet, Idle jet and what Needle did You use ?