Modern Vespa

Once again, thanks.

Do you have to replace the throttle cable or will the original one work? I've found it a pain in the arse removing all the bits in the way to route stuff through the chassis, total bonus if that's not required.

I'm using the original one. That was another reason I went with Mikuni over DellOrto.

That's excellent news, so, does it fit under the pet carrier, and did you use a pod, or just free up the airbox? I would much rather free up the airbox as I tried a pod and it sounded bloody awful. Extra holes in the airbox just added a throaty induction sound which I quite like. I don't need every last hp, but a bit of mid range would be nice as all low end torque has disappeared. It pulls really well at 8800 though and sounds great while it's doing it.

What is you price on this carb? I haven't searched locally yet.

I’m kinda sorry this thread didn’t keep going. I’m planning on doing this project this one along with the links created in it is very informative.

Caketin did you ever get the Mikuni? Did you ever find your low end torque? What did you do and how’s the bike running now?

Hi Rob,

The bike is going perfectly 6000km later. I decided to stay with the original carb, just jetted it to 105 (I think) as the torque low down issue is really only for a second off the mark. If anything, it's even better now than when first built. That could be the belt and rollers settling in. Full throttle gives between 8900 and 9100 rpm with the Malossi variator and 12.5g weights (a mix of Vespa 11g and Malossi 14g). It pulls strongly and sounds very sweet at that. It is still as smile inducing as ever and I ride it most days

It is because everything else is so sweet that I chose not to risk all for a slightly better launch to 30kmh. If I roll the throttle on from a standing start it gets to clutch lock just as the rpm hits peak HP so it's not an issue really. The lighter variator weights do pull the rpm up at light throttle more than is needed, but not so much as to be irritating. light cruise is about 6000rpm, deceleration 4500, and full noise 9000.

This really has made an extraordinary difference to the bike. It feels slow and scooterish (and safe) up to half throttle, then snaps into tune the way you would expect from a tuned two stroke at about 2/3 throttle. The exhaust note changes to an encouraging roar and she's off. Vespa should have built them this way from the start!

Outstanding. Thanks for the update

Hi Rob,

did you ever start this project? I'm curious how well the set up would work with a GTS300. I suspect the fuel system would cope with the Malossi kit better than my carbureted GT200, the GTS having O2 sensors and all, but I like having control so I've put up with the limitations of a carb. The LEADER seems more happy to rev than the QUASAR, but I don't know if that holds true when you start playing with it. Before I spent the money to mod my old 2004 GT I rode a 2015 GTS300 to see if I would be better off just buying one of those. It certainly pulled well from low revs, but I didn't get any eye bulge which is why I decided to play with mine. I also like that it looks a little shabby, it's more fun to surprise other road users with