Modern Vespa

So just building another 232 as per my usual setup...

232 top end
57mm quattrini crank
malossi 30mm phbh carb and x360 intake
SIP 3.0
probably do a static vape this time.

I normally just change from 23/65 to a 24/65 but thinking maybe different gearing for this one... maybe a 24/63. Do we/you think that's a good option? 232 will pull that? What about 24/62?

Will it pull? Depends on how much power you have, especially through the lower RPM range, unless you're going for revvy so you have more room for downshifting.

Which brings me to my next though...you have some interesting build choices in there. Why 57mm instead of 60mm for the crank? 60mm will be a better fit for a touring build.

Likewise the static timing. That may actually be material here, because if set up correctly, it's going to give you about an extra 1.5-2 HP from 3,000-6,000 RPM's. That makes a big difference when holding speed up a hill in 4th.

I don't think you'll have any problems pulling 24/65. I don't fully trust my calc for HP required to overcome air resistance, but it says you need to be putting out a little over 31 HP at 80 MPH at 7500 RPM. (I know that I can break 80 pretty easily on my Lammy, and it only puts out about 27 HP.)

24/62, also probably do-able, but you may find that it costs you a lot of lower-end rideability or you're going to spend more time screaming in 3rd than you otherwise might.

Either way, I'll look forward to updates, pictures and video

You probably have plenty of power in any case, but it's fundamentally a physics question.

I'd probably swap in a 36T 4th if you're going with that tall of a gearing.

Hey Chandlerman...

The 232 is quite a torquey engine as it is, aim is for more low end torque as it is an all round scooter, not wanting a revvy "on the pipe" build. I choose to use the 57mm crank as it fit straight into standard cases without having to mill the fw side out to 100mm... these not much meat on those og cases after you do that sort of milling. I find the 232 the perfect engine choice.

I know it can pull the 24/65 gearing as that's what I've done in about 8 -9 builds that I've completed over the years. I have a feeling 24/62 would be too far, that's why I'm thinking 24/63 + maybe short 4th? 

Like I said, I'm not worried that the motor can't do the job . It's more a matter of "how low can you go?" and still be able to maintain speed in 4th gear.

As to the crank...a 60 mm crank will fit standard cases without machining. It's only when you go to the 62mm+ that you have to mill anything.

As to the gearing, 24/62 w/ 36t 4th gives you 83 MPH at 7,500 RPM's and 39 MPH at 3,500 RPM's.

I think that'll work just fine. I still think you'd be better off with a variable ignition, especially with the longer gearing, but I don't think it's necessary by any means. Even if you're not lugging in 4th at 40 MPH, that's still only 5,000 RPM's in 3rd, so I see no reason it wouldn't work.

Hell, you could do it in 2nd if it came to that and only be at 7K.

Final question I'd ask myself is "what speed do I intend to cruise at, and at what sort of inclines?" and target 4th accordingly.

Like...I went to a very short 4th in my Smallie not because I needed to, but because I didn't want it to go 95 MPH. (The fact that it'll race up to 85 like nobody's business is just an added bonus)

I would simply start with a 62 or 63 tooth BGM primary gear, and buy 1 or 2 extra clutch gears. No decision now, swap your clutch gear and then work out what's best.

https://www.scooter-center.com/en/clutch-incl.-primary-drive-set-bgm-pro-superstrong-2.0-cr80-ultralube-sport-alu-type-cosa2/fl-primary-gear-bgm-pro-62-tooth-straight-vespa-px80-px125-px150-px200-cosa-t5-sprint150-veloce-rally-gtr-ts125-super150-vbc-25/62-tooth-bgm8625kt62?number=BGM8625KT62

Known good - 24/65 = 2.70

23/63 = 2.73
24/63 = 2.625
25/63 = 2.52

23/62 = 2.69
24/62 = 2.58
25/62 = 2.48

Also, are you building this for someone else?

+1
62 straight cut ring gear

My Pinasco 225 has the Malossi 24/63 setup and a 36T 4th gear. It pulls like a train, and most of the time with a pillion, so yours will have no problem.

yeah, that could work.. the engine build is for me, it's going in the Rally.

Yeah, this is what I'm thinking, the 36T will pull 3rd and 4th together.

Stuart,
As far as i can tell you are using the incorrect base calculation as a starting point... PX200 has 10" ... you meed to adjust settings for 8"

No, just rechecked it, it's correct to 10"... why do you think it's wrong?

That's coz 232 & 8" kinda sounds... well... better-err

mmm, 232 in VNA on 8s... sounds like a winner in my book

19hp on low profile 8's has been done already here in Finland. 30 on regular 8's should be no more sketchier than this: