Modern Vespa

Long story short, a friend had acquired an old skool sprint. Looks great, most likely a SEA bike it's had an engine rebuild, seems to be riding ok. The thing looks new. Doesn't get a ton of miles so not too worried about that at the moment.

But the area he lives in is pretty hilly, not long hills but 1:4 gradient slopes and he's 2up. So the engine struggles at best… engine is stock.

But I was wondering any gearbox changes would help out with the hills? Doesn't need to be a speed demon, but with those hills and stock engine, with the wife thinking if it's going to roll back down anytime soon, I can imagine me running up would be faster.

I'm thinking 2 directions:

1. Just changes to the gearbox and primary. I'm imagining no changes to 1st and 2nd gear to be too crazy as the engine probably wouldn't be able to transfer enough power to the rear.

2. Or would the best bet be a new Engine rebuild with a sensible kit, new internals, keeping it stock looking. So nothing exotic.

What gear ratio numbers are we looking at?

I'm thinking at about 8.5 hp that is more than enough to haul two adults up hill in first gear.

The secret would be to get into 1st gear early before the 1:4 gradient and keep the revs up all the way up.
Worst would be to struggle in 2nd or third and then change to 1st halfway up after all the speed/revs have been bled off.

Vespas come from Italy where they do have hills and carry passengers.

Even with a stock PX, those hills arent the most fun.

The Vespa will definitely go up those hills, but like I mentioned, it's barely passing 20km/h and youre hitting 5-6000rpm.

Second gear is definitely no go, that's when you start slowing down.

With a street full of people and a row of cars behind you, it's not a great look.

Put it back on 8"

The Sprint came with 8" wheels?

no, but... because of the dubious origins it could have some wacky 8" gearing in there.

I think you need a kit, 20/20 and some P125/150 gearing... that should haul the mail just fine and dandy.

It should go up the hill.


Check your carb jetting and/or install a lighter flywheel.

I have no idea what the transmission and gearing were (i assume all stock?). But i used to have a 1971 GTR that had a stock cast iron 150cc cylinder swapped on. That with a 20/20 carb and a Sito+ made that scooter a hill climbing champ. I live out in a very hilly area and though the GTR has a tip top speed of about 55~60mph, it would climb the steeper hills better than all of my stock 200's. The only reason i sold that scooter was because i need all my bikes to have at least a 65mph top speed.

yeah I was gonna say, most of the early stuff is kinda billy goat status. with a 20/20 and sito or comparable exhaust it should have no problem getting there.

the only thing I can surmise is a slipping clutch, wack gearing or a woeful carb situation-- like a 20/15 or poorly jetted 20/17. I mean, it's also a possibility that the motor is just slap ass wore out and it doesn't have enough power to pull a sick whore off a piss pot...

I'm assuming it's stock. Won't be taking the cases apart anytime soon to check.

But thinking of options to address the "no fun" riding.

I remember riding my stock PX up those hills and other hills in the area. You have to prepare a little run up, so if there's a slow moving car or cars over taking each other, it's again not a great situation.

I guess I've taken it for granted when I started riding with the dozen or so malossi 221 configurations I went through… just pulls even on the slope.

I even more spoilt with the smallie 170… that eats hills for breakfast. Accelerates in 3rd up hills. It's a bit crazy…

Check the compression, maybe rings are shot.

Check carb size.

Check timing.

Basics first.

Yeah will go through the basics when the time comes…

I don't think there's any crazy gremlins… he's been riding around on it for probably 2 years or so, and before that he had a restored stock PX so he has something to compare it to. I haven't had a chance to inspect it, although it's most likely a SEA bike, it was rebuilt locally.

How well rebuilt? That's anyone's guess…

200 motor... on 8"... problems solved!