Vespa Smallframe on the test stand Polini Evo 133, L&S Franz, Polini Membrane, MRP
Vespa Smallframe with Polini cylinder over 20HP
Today our customer John was again with his Vespa Smallframe on our Scooter Center Test bench.
More power for the Vespa
During his last visit, he asked us what changes he could still make to his engine in order to find a little more power.
After we had briefly discussed what its current setup looks like, we were actually able to give some pointers through which more top performance can be obtained.
Motor setup
Basically, the engine is equipped with a Polini Evo cylinder, a 54 bgm crankshaft. The 30th Mikuni TMX carburetor is attached to an MRP suction device. The very best prerequisites to become a clear Ü20 unit.
With an additional processing of the outlet and the conversion of the Polini membrane to 2 flaps, the following result comes out:
With Kytronic even better
Due to the larger outlet area, the exhaust can work much better. The small loss at 6500rpm is unfortunately due to the missing Kytronic. In the current state (red curve), a standard PK ignition system provides a ZZP of 18 ° before TDC. their service. With the Kytronic it is certainly possible to shift the red curve back to the left at 200 rpm, in the direction of the performance that starts earlier.
But all in all a nice number - have fun with it on the street!
(AS)
How can that be “just so little” performance? Didn't you have more power some time ago with almost the same setup (even worse pot)? According to GSF members, more than 25PS - plugged in - come out of it.
Hello, the performance of the engine always depends on the customer's request and the associated revision and components used. Therefore the customer has achieved his wish to build a very relaxed drivable engine. With a Kytronic or another adjustable ignition, the performance curve will also change before the resonance starts.
The same setup only with the 133 direct / membrane has put around 25HP. This shows what a difference membrane makes.
Is the BGM wave a full cheek wave? Which control times are recommended for this setup and which ignition settings are used on a Vespatronic.
Please give the article number of the BGM shaft.
Thank you!
Which hd do you have in it?
Have almost the same setup and I'm still voting.
Hello Lukas, the main nozzle for such engines is usually between 270 and 300 together with a power jet nozzle between 50 and 80.