You may recall from last month’s column that we had a nice chap named Dylan visit the dyno to have his Vespa 210 Malossi with SIP3 exhaust run up on the dyno. If one of these kit and pipe combos is built with all the right details and tweaked to suit, then we could see around 20+bhp on the dyno. Dylan’s scooter, however, was only pushing out 9bhp at the rear wheel, which is the same output as a completely standard P200 straight from the factory.
Upon investigation, it appeared that Dylan had a crank that was still using the standard rotary inlet, but with a single-petal reed valve bolted between the Si24 carb and the engine casing, since the seal on his rotary pad had failed. This mismatch of components, along with a few other minor niggles, had a huge impact on performance, effectively killing the power output.
Dylan took the scooter away and made the following changes: rotary-style crank removed and bell-shaped reed crank fitted. Standard carb and single-petal reed valve removed, and Dell’Orto 30mm PHBH carb fitted, along with Malossi reed valve intake and manifold.
These two simple changes alone almost doubled the power output of the engine and bumped the peak power up from 9bhp to a much-improved 17bhp, while providing more power and revs right across the entire rev range. Result!
While setting up the carb to get Dylan’s jetting into the correct air/fuel ratios, we had a further discussion about what other modifications could have been done in order to release even more
