Modern Vespa

For those who have installed stock P200 engine in older scooters and stuck with the 8" wheels, what gearing did you go with? Yes, i'm looking to install a stock P200 in and oldie with eights. I do plan to use a 36T short 4th gear, 24/24 carb, and a box exhaust. I've looked at both the gearing calculator at scooterhelp and at gearcalc. There seems to be some discrepancies between the two websites.
https://www.scooterhelp.com/tuning/vespa.gear.calc.html
http://gearingcalc.free.fr/

I was kinda eyballing both the 24/62 and 25/62 DRT primary setups-
https://www.sip-scootershop.com/en/product/clutch-gear-cog-24-teeth-drt-for-clutch-cosa-2-for-primary-62-teeth-for-vespa-125-vna-ts-150-vba-super-180-200-rally-px80-200-pe-lusso-cosa-t5_87482400

https://www.sip-scootershop.com/en/product/primary-driven-gear-62-teeth-drt-input-shaft-for-vespa-125-vna-ts-150-vba-super-px80-200-pe-lusso-1994-cosa-1-125-200-t5_40432930

Benelli also has the 24/61 gears in kit form. https://www.sip-scootershop.com/en/product/primary-driven-gear-kit-with-clutch-pinion-24-61-254-teeth-benelli-for-vespa-125-vna-ts-150-vba-super-px80-200-pe-lusso-1994-cosa-1-125-200-t5_88109980 This ratio pretty much splits the difference between the DRT's 24 and 25 tooth clutch gear, and it looks like it will give about the same (theoretical) top speed as a 10" P200 with a short 4th?

My plans are to use a cosa style clutch...possibly a VMC if i can't find a good used stock cosa in my shop.

Do you 60/8 going plaid experts have any advise or input for this particular engine? I know most of you just have kitted smallblock engines, so that will perform differently from a stock P2.

stock p200e cylinder- 24/63

That looks like a gearing i'd really like if i still had the stock 35T 4th gear, but since i install a 36T short 4th, that 24/63 is looking a bit to low for highway cruising (i forgot to mention that this scooter will be a highway commuter). That's why i was looking at the 24/61 which is just ever so slightly taller than a 10" P200 with a 36T 4th, and still lower than a 10" P200 with a 35T 4th)...then i figure if i go a smidge bit lower gearing than a 10'' P200 with a 36t short 4th, then i should get some more torque out of a 24/62 instead?

All my stock 10" P200 engine builds can pull a true GPS 70+ mph with a 36T short 4th and a Sito+, so i'm kinda hoping for similar MPH numbers when running on 8's.

-P200 with 8" tires
24/63 = 2.63 ratio + 36T 4th @ 6000rpm = 58 mph

24/62 = 2.58 ratio + 36T 4th @ 6000rpm = 59.7 mph <---- possible winner?

24/61 = 2.54 ratio + 36T 4th @ 6000rpm = 60.6 mph

25/62 = 2.48 ratio + 36T 4th @ 6000rpm = 62.1 mph


-P200 with 10" tires
23/65 = 2.82 ratio + 36T 4th @ 6000rpm = 60.4 mph

23/65 = 2.82 ratio + 35T 4th @ 6000rpm = 61.8 mph

*NOTE: i got all my numbers from http://gearingcalc.free.fr/

Dangit whodat, you brought me out of posting retirement 😉. I just did a similar build this year for my VBA on 8". P200 O-tuned that is similar to Swiss1939's "First full restoration project.. 1980 P200E" build: Stock cylinder but widened exhaust port by 5mm wide and 2.5mm taller, Grand Sport piston and ground ~10mm higher transfers higher, poor boy ground cylinder head to decrease squish, 60mm SIP crank 45021510 with longer duration (total intake duration came out to 180 degrees, didn't touch rotary pad), SITO + pipe, 24/24 carb, SIP Vape ignition, rebuilt stock clutch, Malossi 24/63 primaries, stock gears. She will cruise at 60mph and top speed with a good tuck will tickle 75mph GPS. I went with the Malossi 24/63 gears bc I had them used on the shelf and I was going with stock clutch. I was tormented about putting the 24/63 gears in bc it is less top speed than stock P200 on 10's as you pointed out, but didn't want the budget to get out of control. Thankfully once I got her running and riding I was happy with my decision. That said, if I didn't have the Malossi 24/63 on the shelf I would have run a 62 tooth w/ either a 24 or 25 tooth so that I could have options later on down the road without splitting the cases. FYI the Malossi and BGM gears do not appear to be interchangeable, I checked when I had everything apart.

For clutch, you may want to consider getting a BGM superstrong clutch from scooter center. It is made from the same people that make SIP ultastrong clutch, however they have options that you can bundle it with a primary gear for not much more money. Choose your options carefully bc BGM offers this in a bunch of variations. I also like the BGM stuff because the clutch gears are interchangeable, the straight cut at least. You could buy the 24/62 and if you needed longer you could buy just the 25 tooth clutch gear for $80. For a different build I didn't know if the P200 engine was going in an 8" scoot or 10" scoot, so I went with a short x-mas tree (12, 13, 16, 19), a 62 tooth primary and 25 tooth clutch gear for the 8" and 23 tooth clutch gear for the 10". It wasn't perfect but made them only be 3.5mph @ 6k different (made the 8" scoot a little short and the 10" a little longer, so both options were a little compromised. Would not recommend this route.).

I don't think I would go Benelli 24/61 because of the cost, less options if you change your mind, and slower top speed than a 62/25. BTW I ran the calcs on my setup 24/63 w/ stock gears and your potential option of 24/62 and short 4th, top speed for 24/62 was only 1 mph less from 6k-8k.

Gearing calcs:
I use my own spreadsheet so I can compare 6-8 different combos at a time. I use a 14.5" diameter for 8" tires and my number seem to align with the scooterhelp calculator.

TL:DR: Stop torturing yourself, go 25/62 BGM straight cut combo. If you end up having trouble pulling it, you can always drop down to 24 or 23 teeth for cheap without splitting the cases or just add more power.

^^^
5 Stars

I have ridden Captcha's Turquoise Terror. It is an absolute gem. Great torque, with the right amount of "wow" but without any of the "oh shit" crazies and hella respectable top speed. Just front to back solid.

I appreciate the long reply Captcha! That's a lot of great info. Agreed on the Benelli on both cost and the odd primary tooth count that might be difficult to play around with different clutch cog gears at a later point.

I looked at the BGM clutch at SC. They do sell a large package kit that includes the clutch, clutch cog, and their billet clutch cover!…but they're all out of stock on them. The main reason i'm looking at the VMC clutch is because it's fairly lightweight, and a lightweight clutch is easier on the clutch from a longevity standpoint and it lets the crankshaft spool up quicker as well. I'll have to spend a few hours over at the SC website to look deeper into the BGM clutches and gears though.

I'm still contemplating the little bit lower 24/62 (instead of the taller 25/62) is that the scooter has a saddle seat, which means as a 6' tall man i won't be able to tuck down very much with the headwinds. That and there are LOTS of hills and headwinds where i ride.

I've also been wondering if there's a noticeable difference in acceleration and power between an 8" and 10" scooter if the overall gearing is matched to be the same? For example, for installing larger offroad tires on a pickup truck, you would install a lower set of ring and pinion gears in order to offset the taller tires. But even if you match up the new lower R&P gears to the new taller tires, it will still loose power when compared to the original smaller tires and taller R&P gears. I can only assume that it has the same effect with 8" and 10" scooters as well?

This for sure.

You can even have one on the shelf and swap if you decide to go riding on the flats for a change. Brings the "which one?" decision into reality testing territory.

I have my Malossi 210 with stock gearing in my VBB right now and it performs almost like a 150 gear stack, but with more torque on the low end.

Ok, I'll take the bait!
Have you been talking to Ginchi?

If I were to go this option, which is the option I would prefer if using a 200 motor, then I would stick with the SAME gearing as Speedy, but a slightly LONGER primary, as a lot more torque means longer gear would be ok, which means an easy 70/8

NOTE: Speedy's VBC1 motor is using a PX-EFL box.