I pulled the RD engine this weekend and disassembled everything. Of course it will get new bearings and seals, the crankshaft is still very good, as are the gearbox and clutch. But the clutch has to go, it’s a two plate model, i will try and fit a four plate clutch from a DT80.
There will be some machine work done to the crankcase, as i will fit a cylinder from a Minarelli scooter engine. The gasket surface needs to be lowered 2-3 mm, the bore for the cylinder skirts will be enlarged and the transfer ports need to be matched.
A new project again. I’ve had this Yamaha RD50M for a while, and no plan for it. It’s a german 5 speed model, it can never be ridden as a Moped in Denmark. What better to do than a tuning project?
Right now i’m stripping it for parts that i don’t need, less weight and fewer parts that can fall off 😉
The engine will get new bearings, seals and some porting for a larger cylinder kit. At the moment it has a 45 mm Polini kit with a 20 mm Mikuni. A good daily driver with a topspeed of 80 km/h, nothing you can win a race with. I need something faster, more about that later.
The gallery will be updated with more pictures in the future.
A complete guide to rebuilding a Piaggio moped engine, like you would find in a Vespa Ciao, Bravo, Si, Grillo, Gilera Citta etc. I talk about changing bearings, measuring the ignition components and more.
My friend needed a new moped after his Ciao was stolen. I found a 1995 Vespa Bravo for a good price, or so i thought at first. It had some nasty damages to the engine and gearbox. But i managed to find some spareparts for a small amount of cash.
Here is the progress so far, stay tuned for future updates:
Next Vespa Bravo upgrade, a Polini Speed Engine. A very nice engine case with enlarged intake and bored to accept 46 mm cylinder kits. Nothing you can’t achieve on a stock engine case, but i got it for a good price from my friend Nikolaj.
I bought a special intake manifold from Italy, made for a 15-16 mm SHA instead of the normal Piaggio SHA 13 mm carburetor.
I mounted the engine with a used original crankshaft, new bearings and seals. The intake opens 130° before TDC and closes again 51° after TDC, giving me a total duration of 181°. Good for many of the cylinders that are out there.
The setup will be:
46 mm Polini cylinder kit
Dellorto SHA 16 mm carburettor – changed to 13 mm
Proma Circuit exhaust – changed to Sito
Polini variomatic – changed to non-variated
Stay tuned for future updates!
Last update, the Bravo is done for now, onboard video: