Modern Vespa

Hello Folks..
I'm a long time stalker here, and decided to join last night! LOL

Out of my curiousity, is the taper profile between earlier small frame (Pre PK) is the same with pre P series Large frame?

And, how about the rivet hole?
Do they have the same diameter and PCD (hole pattern)?
As far as visually inspected, they both have 8 hole rivet hole,

Cheers guys..!

Hello!

With my limited experience, I think even if your taper is the same, the clutch side bearing and stump is a different size.

The bearing is much smaller on a smallframe.

There's couple unused large frame small taper for sale, so I'm planning to try to use them as a flywheel for my Full DC and external pulser pickup conversion.

Based on your answer, it seems that the flywheel would sit squarely on the small frame flywheel side stump, am I right?

Ah, you're not planning to use the whole crank? Just the taper side of the crankshaft?

Not too sure your situation and your end use then.

Looks like youre interested in flywheels. I dont think they'd work as each crankshaft flywheel cone has a different length and taper.

Swap flywheels on any of your scoots with your smallframe and compare.

Yes exactement yes,

I'm interested and planning to taking pre P series (thin taper) flywheel, machining to remove the fins also reducing weight to 1.8 kgs, and then adding plastic fan to it, plus adding some notch for the external ignition pulse trigger

That's why I asked if someone here have tried to measure it before.

Why not just do that to the one that suits your motor?

Smallframe flywheel is crazy expensive here, like 3~4 times the price of largeframe motor flywheel

Looking for cheaper alternatives here, sorry 😞

Have you researched about the weights for flywheel vs clutch?
Imbalances & vibrations can cause issues

Of course I did,
It's a problem isolated with large frame vespas, since their clutch is mounted directly on the other side of crankshaft.

The small frame crankshaft got nothing in the other end, just a small primary drive gear

Yeah, true.