Modern Vespa

SIP do two grades of spring for their rear shocks, they label them M and XL.
Whatever is fitted to the shock that came with my scooter is way too firm, I suspect it's the XL rate but I couldn't find any markings on it. I don't really want to buy and fit an M spring only to find that it's no different.

A bit of a long shot but if anyone has one to hand that knows of its an M or XL could you measure the wire diameter please? (A count of the coils would also help but assuming the pic on SIPs site is correct then I count count then there)

I've also asked SIP but I'm not confident that I'll get an answer.

According to SIP, all their shocks come standard with the M spring with 70 LB, 110LB, 150LB stiffness depending if it's front, rear, having or not the extra reservoir…

I hadn't spotted that, but I did read on the page for the spring that prior to 2010 all rear shocks came with the XL spring. I don't know when mine was purchased, the previous owner bought parts over a range of around 2008 to 2012 but the project wasn't really started until we bought it.

It's the one without the extra reservoir.

A quicker way to figure this out would probably be letting us know how much you weigh. If the shock has the medium spring, then it might feel stiff if you weigh around 130lbs. I have a few of their medium spring shocks in my scooters, and with myself weighing in at just over 155lbs, the spring feels just right for me. Hope that helps.

That could work.
I'm 11 stone 5 pounds so 159 pounds.
I've wound all of the preload off the spring, turned the damping all of the way to soft, switched from a sporty seat to a standard one, and the ride is still really harsh.

I haven't tried to properly measure the sag but when I sit on the scooter there's no noticeable movement.

The preload sets the ride height and doesn't make the spring any softer when you loosen up the collar. The damping controls the rate of how quickly or slowly the shock's shaft will compress or rebound. I'd say that you have the XL spring and not a medium.

Just tried to fit the new spring and the ID is too small at 42mm vs 44mm for the old one.

Old one is labelled 110lbs. New one isn't labelled but it has more turns so will be a lower rate.

Irritatingly I can't find the receipt or any related emails to figure out where I bought it so I can return it.

Here's a pic