Modern Vespa

Hi folks,

Anyone happen to know what's the difference between forks of Px, Pk and Pk XL? I heard somewhere that on one of the Pk's is the shorter fork than on the Px.

Scooter & Service is providing superlow kit for Px, but it is unavailable at the moment, so I am trying to find out if I can do it myself and avoid shortening of the Px fork.

PK and some of PK XL can have V-range type fork but with little different shock absorber top mount. You don't need this type of fork.

Also PK and PK XL can have "px-style" fork with 20mm axle. The fork leg is shorter than on PX and shock absorber length is less - 205mm VS 245mm. So it can be used to lower the front end.
But I'm not sure about steering tube length and mudguard mountings. More likely that it will require some adjustments.
There also ZIP 185mm shocks absorbers that suitable with PK fork but it require leg shortening for 25mm but it make you PX front end more lower.

Anyway there is no plug and play suggestion for your question only buy ready conversion fork.
But IMHO the easiest way is to shorten leg on your current fork and use shorter shock absorber.

Here you go.

As Roland says, you can use a shorter shock to lower it, but apparently handling suffers as the swing arm gets flatter. Can't recall where I saw that but the person was speaking from experience. Plus it looks wrong. But if it's only a little bit you're looking for it ought to be fine.

I've found it wasn't very expensive to get a professional welder to cut it down. My guy preferred to cut and sleeve internally, but cutting through the weld of the lower 'knuckle' leaves the internal plug part intact, ready to weld back into your shorter fork. That's what I'll get done next time. It could work out quite a bit cheaper than S&S.

I can see some pros and cons to both methods. If you do the cut and sleeve method, you can make a very tight fitting sleeve to pound into the fork. By doing that, there's a better chance of keeping the camber (or maybe parallel is a more accurate description?) from getting too far out of line. If you cut the weld out at the bottom of the fork, that slug that's inserted at the bottom most likely won't be accurate enough to keep the axle spindle perpendicular to the fork leg.

The aesthetics of a lowered PX is up to the owner. I will say this though, when you lower a Vespa, you will loose precious ground clearance...which isn't a big deal until you have to make a sharp left hand turn and your exhaust grounds out on the tarmac.

Yeah I see what you're saying. You'd need an accurate jig for a start.

I mean shorter shock only in pair with leg cutting.

Where you got this chart with measurements please? My friend want to change fork on his Sprint to PK/PX one so I start to collect information.

I think it came from the GSF? I found it years ago now so not sure.
When I did my VBC I think the PX one needed to be cut 35mm shorter.

Only leg cutting is needed? How about steering tube?

No the top part is fine if it's going into a largeframe - although you need to alter the steering lock position if you want to keep using it.

Here's my thread from 10 years ago - Fork Swap for 150 Super
Just note though, Whodatschrome has pointed out from time to time that bringing the top of the shock in like I did can lead to shock collapse. I haven't had that issue myself but I see that it's a definite possibility.

Another side note is that although the steering stops were fine on that one, a conversion I did for a friend had issues with them. I can't quite recall what the issues were now (it was a long time ago) but anyway, just something to be aware of.

Great info! Thank a lot!

Happy to help!