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.
A local guy brought me this engine, he bought it restored many years ago, but didn’t use it much. The changing temperature differences gave condensation in the engine case and caused a lot of rust damage. The oil was brown and very thick like mayonnaise.
I changed the damaged parts, did some machine work to worn bushings and rebuild the engine with new bearings and seals.