When stock is not enough
I’m not ashamed to admit I’m completely satisfied with the GTS’ performance. I feel no need to tweak around with the engine, or to add a performance pipe (which to me makes a modern Vespa sound like a DR Chipper-Shredder®). At the other end of this spectrum are the folks who have the performance parts ordered even before taking delivery of a new scooter. Owners of 4-stroke Stellas who fall into that latter category will surely be giddy at the latest offerings from Scooterworks.
Their most recent weekly e-mail included these tasty items:
Someone had a Pinasco Stella 4-stroke Performance Exhaust on their 4-stroke Stella at Amerivespa. (I know this because I saw a picture… I wasn’t there, remember? :( )
Now that 4-stroke Stellas are in the U.S. in significant numbers, and since the word on the street regarding a possible Stella 200i is “don’t hold your breath,” one of these will be the only option for those desiring more oomph.
Like all other performance pipes for internal combustion engines, this one is less restrictive than the stock exhaust. Like a human (or, I suppose, animal) athlete, better performance is achieved if breathing can be improved. A pipe like this aids in evacuation of exhaust gases. And it makes your Stella sound really cool, too.
A less-restrictive exhaust also means the engine can ingest a larger quantity of fuel and air. If you only installed the pipe, you’d need to upsize the carburetor main jet to keep the engine from running too lean (and therefore, too hot, an important consideration with an air-cooled engine).
To achieve the full effect, Scooterworks and Pinasco recommend replacing the stock Keihin PB carb with Pinasco’s carburetor upgrade kit, which includes a 21mm Dell’orto carburetor and all the necessary bits and pieces, including three different-size main jets. A power increase of up to 20% is possible, sez Scooterworks, though you will initially need to try the different jets (and maybe some others) to achieve the optimum chocolately-brown spark plug.
The pipe sells for $499.99, while the carb kit costs $257.99. Plus S&H and sales tax where applicable.
If you’ve done this upgrade, or plan to, please let us all know how it turns out!
(DISCLAIMER: I received no compensation whatsoever from either Scooterworks or Pinasco for writing this article. It appears here because I consider it newsworthy, and of interest to owners and riders of Genuine Stella 4-stroke scooters. Thank you.)