Modern Vespa

My LX50 scooter mechanic installed a new set of Malossi parts: the 70cc upgrade kit; a new Delta adjustable clutch, new variator, new power cam, new Kevlar belt. The torque difference is fantastic! The speed, however, has dropped significantly from about 43mph indicated, to 35 mph, and won't go any higher. The mechanic thinks it has something to do with the rollers, or maybe it needs new jets (jetting), or perhaps it's an air intake thing. Might even be a clutch adjustment. In any case, I love having the torque to jump from the start, and it's especially great going uphill, but the speed thing is very disappointing. Has anybody out there figured out the "right combination" to get the speed this little scoot is surely capable of? I don't use the scoot except around town, but on straightaways it can be very annoying to cars when I can't keep up to even 40mph. I saw a post earlier where a guy had done all of the upgrades, and described the speedometer as "off the scale". Any help/advice/suggestions would be greatly appreciated!

I only had the cylinder kit and variator done, which got the LX50 pass 80km/hr on a down hill stretch. I would say a realistic and sustainable max speed is 70 km/hr (43 miles/hour).

Try some heavier rollers to get higher top end.

H