Making a stock PK125S more efficient

Hello everyone

Since this is my first post, I apologize for any "malapropism" or incorrect term I might use.

First, some context: I decided last year to take my father's old Vespa out of the garage, and put it back on the road, since I'm currently in need of a personal vehicle other than a bicycle. However, due to college exams and such, I took it to an official Piaggio workshop. I wasn't sure what to fix anyways, or what was wrong with.

I got it back after some time, and was very satisfied with the results. The bike started without too much kicking (5 or 6 if cold in the morning, 4 if warm afternoon), nice ride on the city, a lot of fun with the gears, increasing levels of wanderlust. You probably heard this story, or even experienced it yourselves. Now to the bad part:

I'm slightly disappointed with the bike in terms of power. I know, I know, it uses old technology (2-stroke, carburetor), it's almost 40 years old, etc etc. I understand that.

When I ride it alone in the city, it's more than enough, never left me in the dust. Good top speed, decent acceleration, superb maneuverability, good visibility.

But when I'm riding with a passenger, it's just slow. And when we go for a ride on the national roads (Spain, speed limit 100km/h, nobody gives a feck about speed limits), the engine just can't keep up. At a 20% slope, passenger and me, fourth gear, full throttle, it reaches MINIMUM speed limit, 50km/h. I started worrying about temperatures and engine seizures, but nothing happened. How can I travel long-distances with my partner, when a short ride becomes a stress-test? Maybe I was over-cautious, maybe I was realist.

Since I don't have a lot of experience, or even specific tools (flywheel remover), I'm interested in upgrading the bike in the most simple ways. The Spark Booster (blue, cheap one) from Kytronic looks very interesting, and the very few (3) reviews I found said it really worked. The SIP SITO exhaust series seemed very nice too. I don't even need to reach highway speeds (120km/h), just a little bit of extra power.

What would you recommend me? What should I do? Should I stick to urban riding, or can I really travel around with my Vespa?

Any advice, recommendation, or lesson, no matter how harsh (no insults, just tell me my bike is small and old) is welcome.


TL;DR: Bike (PK125S, stock, no upgrades yet) is very nice, but I think a little more power/efficiency is needed to travel around. Suggested upgrades: Spark Booster (Kytronic), new exhaust (SIP SITO Plus), maybe a bigger air filter?

-Possible upgrades?

-Not very experimented with transmission or engine repairs, I only repaired fairings and electric parts

-Driving techniques for long-travel plus driver and passenger?


Thank you very much for your support and understanding




‚However, due to college exams and such, I took it to an official Piaggio custom writing workshop. I wasn’t sure what to fix anyways, or what was wrong with.‘

I needed it for studying so I also had no time to find out how to fix it, I had it fixed by their service.

The Spark Magnifier from Kytronic turned out to be a very good choice, it allows my engine to rev up faster and easier than before, meaning much better acceleration. It makes it easier to kick-start too.

Now I'm going to replace the clutch plates, or even the entire clutch basket, because it's getting very "slippery". The SM had nothing to do with it, but like SIP Scooter says in their catalogue, "it's the MOST important part of the power transmission".

I don't want to replace the exhaust with a SITO Plus, because I'm always complaining about loud bikes with "racing" exhausts OUTSIDE speed tracks. I'm not a hypocrite. So I'm probably going to replace it with a standard SITO exhaust.

Music and community's shop is opened for the switching of the news for the users. The approach of the music and students is inflicted for the depth for the changes. Its impact is run down for the approval of the fought messages for the field and program for all issues.