Modern Vespa

1st gear is very low and near useless in my flat Florida. Has anyone toyed with gears. On motorcycles sprocket swaps are the norm. Clues appreciated!

Is your engine standard?
As for me this issue appears when putting some 177 kit without changing primary gear.
Or maybe in the past primary was changed to shorter one for some reason...

How's 4th? You maybe able to add a tooth to clutch cog, however that's makes all gears higher including 4th. It's a balancing act.

As is 2nd probably. I try and get mine into 3rd as soon as possible. If you are considering staying on the flat and not moving to the hills, then yes you can change the ratios, or even for a simple not get your hands too dirty fix and split the engine case just change the clutch tooth cog which wont make a great difference on the 1 and 2 but slight improve. Swings and roundabouts. However, im very grateful of my 1st and 2nd for hills two up and live with it. Ive seen people walking quicker than scoots on the isle of wight scooter festival whilst they struggle to get up the 2 in 10 inclines.

The easiest thing to do is swap the clutch cog with 2 teeth more (20- replace with 22). Try that with a stock cylinder and a replacement box exhaust (SIP Road 2.0 or 3.0).

If you have a kit installed and it can pull it, then I'd recommend opening the cases/swap gears/install aftermarket overdrive system.

My '05 PX150 came with a 20/68 clutch cog gear and I had the same complaint. I replaced it with a 21/68 and it made a noticeable difference for the better on a stock engine with a SIP Road exhaust. Never tried a 22/68.

Resulting Gear Ratios
2005 primary 20/68-
1st 12/58 overall 16.4
2nd 13/42 overall 11.0
3rd 17/38 overall 7.6
4th 21/36 overall 5.8
1978-2003 primary 21/68-
1st 12/58 overall 15.7
2nd 13/42 overall 10.5
3rd 17/38 overall 7.2
4th 21/36 overall 5.6

I think from 20 to 21, its something like a 6% difference. The way I understand this in actually driving is that if your scooter screams/revs out at 60mph on a 20 cog, with a 21, it wont scream until it reaches 63-64mph. That doesn't sound a lot, but actually when riding on a national speed limit road (UK its 60mph and 70 on dual carriageway) it makes for a lot more comfortable ride, particular on longer journeys or riding with a group of scooterists, and makes your cruise speed of 55+ realistic. So if your scoot can hit 60mph easily and you feel its revving out, the 21 cog sounds ideal on standard with the sip. If you are going to kit with a 177/166 whatever, more likely a 22 cog needed, but depends on where you ride and what you like more, street thrashing acceleration, or touring at higher speeds. Horses for courses.

My 1981 P150X was with 22/68. It was far from good shape when I got it but it pulled really good with this ratio.
Also when I rebuilt engine with Mazzucchelli racing crankshaft, DR 177 with Malossi head, 1.6 kg SIP flywheel, SI 24/24 and SIP Road 2 exhaust - 22/68 primary still works perfect. I tried 21/68 and it was too short and with 23/68 it was too noticeable gap between 3rd and 4th gears, I need to rev 3rd really high to not lose power when shift to 4th. It was ok on long outta city rides but for my mixed usage not.

I await reply from OP before piping up

Not to start an argument here but I documented an entire year in 2021 picking up my son every single day from school and I was rotating scooters. My son and I weighted exactly 400 lbs combined and I found incredibly more useful the short gearing on my PX150 (Malossi 166) and the sprint veloce LML 150cc (Malossi 177cc) rather than the long gear on the P200E (Malossi 210).

I vividly recall being much easier pulling from a dead stop on the shorter gears and I had no problems picking up speed. Ona different note when I want to go fast I find that the shorter 4th gear on the PX150 and the sprint veloce is a handicap in certain situations. I can cruise at 60 mph at much lower RPMs on the P200E without breaking a sweat but the smaller engines are being reved much higher.

What type of riding do you do? If you have a smaller stockfish engine you want to stick with the shorter gears to compensate for the lack of power(my honest opinion).

2 weeks... still waiting!

Not worth answering if you are not even participating on your own post. I was going to respond with a lot of data but I see that you posted 2 post in 3.5 years.