Modern Vespa

So

I've had my PK125XL for a few weeks now.

I've riden it in the dry

I've riden it in the cold

I've riden it in the wet

As soon as the ground gets damp and you are going over ~30km/h the front end understeers so bad.

Feels like it's on ice! I've almost wrecked three times already!

Is this a Vespa issue? A PK issue? Setup? Did someone put petrol jelly on my front tire?

Never had so little confidence in a bike.

What tires? How old are the tires?

PK's are one of the best handling bikes ever produced by Piaggio. I feel like we're not getting the whole picture here.

as above: how are the tires? new, old, odd tread pattern, junk rubber, over/under inflated?

from there, I'd be looking at the fork bearings and making sure those are in good condition and properly lubed and tightened. the same with the front-- rim, brakes, hub, bearings and shock.

don't discount the rear either! worn engine mounts, bad rear shock or even something having to do with the rear tire and wheel combo can have detrimental effects on the handling.

has the bike ever been in an accident? perhaps the fork is bent?

I haven't checked the age of the tires but they still had their nobbs on them when I bought it. Should be just about run in by now.

Fork is supposedly rebuilt, looks perfect to me with no oil dripps or anything, seems to do it's job perfectly judging by how it goes over bumps. Same for the rear. Front looks to be straight. Rear shock looks new or rebuilt, seems good with both spring and dampening.

Basically just as soon as I start loading up the front tire sideways it starts slipping, especially in the wet. Have almost gone into oncoming traffic a few times and almost dumped the bike mid turn several times too.

Worth to check. Some photos will help with advices I think.

Could be some NOS tires, look fresh but rubber too hard and slippery on wet like on ice !

Yes, check the dates. Also, try pushing your thumbnail into the tire. If it's hard as a rock, there is your answer. If it's still a bit soft, check all the suggestions from Greasy - which should be done anyway.

One more thing to check...

Make sure the lower bearing race is seated correctly.

I installed one that was maybe a a cm off center and it completely killed the front end handling. Was super squirrely.

Can you post some pics of the bike?

I'll check the tires tomorrow. Here are some pictures I've taken off the bike

How to read michelin tire date of manufacture codes:

https://www.michelin.com.au/auto/advice/tyre-basics/tyre-markings-explained#:~:text=The%20date%20code%20appears%20at,week%20of%20the%20year%202014.

Those S83 tyres are a very old design. By modern standards the grip, especially in the wet, is pretty terrible.
There are many newer compounds, which are twice as good. If you're going to be riding in the rain often, it would be cheaper (bodywork, medical, lost earnings etc.) to buy new tyres now.

I see it has the newer P style suspension as it's a 125. My PK XL2 has the same and I have none of the problems you've described. But not ancient tires as Jack has pointed out.

If your tire is not too old and if you have it at ~18psi, what happens when you are going downhill straight on good pavement and put on just the front brakes slowly increasing pressure? Does your tire more want to stick or slide, and is everything smooth? I like to do this to test front end stuff after I do a 'new' bike.

I repeat: remove zip-ties that holds cables. But it seems that Michelin improved compound on S83. I have them fresh in 2017 and it was absolutely nice tyres. My friend bought fresh pair in 2021 and it was absolutely different on touch.

Not saying they are rubbish. They have been around a long time. They still only have a maximum speed rating of 62mph. And do not grip anything like a modern Pirelli, Continental, Dunlop etc. They are a retro tyre for retro performance. If you're hanging off your scooter around corners in the wet, there are much better tyres.

S83s are terrible for cornering and fast riding…

Those pictures are from before I changed them, can't remove them or the cable rubs on the tire

Then you cables/outers is too long. Theoretically it affect on the brakes.
I noticed that you have threaded rod that mounts with bolt on standard cable then it is easy to cut outer and cable to proper length.

I done few same forks and never have any problems with cables even with 3.50 and knobby 90/90 tyres.

As for weather, I am far from a fair weather rider. I'll ride in any weather except for ice or storms pretty much

I always pick tires that have good wet weather performance for my bikes. Sounds like I might have an outdated design and maybe old tires. Season is almost over so I'll probably buy new rubber when the season starts again if that's the issue.

What tires are recommended? Not going for crazy performance, just don't want to almost crash whenever I enter a damp turn

Those knobbys look wicked

From those pictures it looks like my cable is about 5-10cm too long. Can you typically cut to size or do I need to order a new one?

Yes you can cut it.
Did you know how to set up proper your front brake system?

You need to un-tighten this bolt then push and hold brake lever and tight bolt down.

Check the age of the S83's as suggested. They can be a bit squirrely even when new though. These Heidenau K58's would be my first choice for the kind of weather you're describing. Really helped me get my confidence in wet and slippery conditions. And great in the dry too.

https://www.sip-scootershop.com/en/product/tyre-heidenau-k58-300-10-50j-tl-tt-reinforced_H1021

What PRESSURE are you running?

On my 8" VBC, I use front: 18psi , rear: 36psi.

I once had swapped front/rear & the original REAR was basically worn with a wide flat area where it normally was on the road due to city riding & not leaning as much into corners... rode on race track & scoot either wanted to stay upright, or fallover, so I swapped to new tyres, problem solved.

Or get sticky tyres!

So i am finally back with the tire date: 2414 the front reads, so these tires are nine and a half years old...

They ride pretty alright in the dry, but i think ill get new tires next season. I'll probably only run this tank and one or two more before i put the Vespa away for the winter.

As for the preassure, i dont really have a good way to check at the moment, they are probably a bit lower than when they were filled up though as the outside temp is about 20C cooler now

Agreed. I have a set of K58S'es (the *snow tire* version) of the K58 that MJRally gave me back when I was still riding in the snow. They are amazingly sticky, but also wear really quickly. Still, I highly recommend them.

I'm also really happy to see that Heidenau have restarted their scooter tire production lines. They were shut down for a couple years during the pandemic.

There you have it. The rubber is dried out. New tires will do wonders for your handling. Good riding next season.

Get a pressure gauge! They are cheap and on these scooters you NEED to run the front at considerably lower pressure than the rear because it has so much less weight on it. When they were 'filled up' they were likely both filled about the same if you had no gauge. That & their age, no WONDER it's sliding all over the place.

Get new tyres!
Tyre shop recommends 7yr max age!
And, tubes, and get a pressure gauge

Getting back to this as the snow is starting to dissapear(probably gona come back one or two or five times tho ) but i started looking at what size i should use.

Seems like 3.0-10 is the right size, but that made me wonder what size i have right now and it turns out i have 3.5-10 on!

Maybe this is why the bowden tube for the front break needs to be zip tied to my fork, because otherwise it goes into the tire. Think i will get the K58 all-season in 3.0-10, hopefully that will solve all my handling woes

So you have 3.5 front and back?

Definitely shouldn't be zip tie-ing the brake cable… because you'll end up braking as the shock compresses.

On white PK at photos front is 3.5 too.
And even with 100/90 it don't need any zip ties.

Yep, 3.5 front and back. The zip tie is on the front only, not put there by me originally. It was there when i bought it, found it when i tried to figure out what made the front break feel like crap.

If it is not there the bowden tube rubs on the tire no matter what i do with it. I have redone the zip tie a few times to try and find the least bad option and it is useable right now, still, id like to solve that

i belive the issue is with the likely aftermarket cable i have, i think the bowden tube is a few centimeters longer which is causing the issue. If the new tires dont solve it, i guess ill have to order a new one or figure out if this one can be modified.

let's see some photos. all the ones you've posted are from an angle or with the bars turned.

front of the bike bars and front fender straight on and same from the side. on flat ground, at a reasonable distance as to distinguish the bits.

the zip tied cables are a bad thing and *might* contribute to it handling poorly, but I doubt that is the only cause.

No. They don't.

Due to the cable is tied to the fork leg and has limited free-to-move, when the suspension is working, the cable is stretched and activate the brakes. I bet OP need to cut cable outer and cable and all problems will gone. Better to change cable for correct one.
Especially that he have not original type of cable but cable with this bolt-clamped end rod.

Id love too but i wont have access to my Vespa for another month or so as it is in winter storage in a garage i dont have access too. This is a crop of the clearest picture i have of the cable situation. I dont have a picture from the front with the bars straight as it wont sit like that on the center stand.

I guess we'll revisit how to get those pictures when you get it back out then.

If the front break is activating with the suspension that could be the cause of my understeer perhaps? But i would have thought id encounter that in the dry too.

Guess ill order those parts along with my new tires then I have replacement pads for the front to put in, should have ordered a new cable when i got that stuff too but i was affraid it would just be the same one i already have

Got the PK out of winter storage yesterday and put the new tires on and WOW! It rides so well now

The K58s are like glue on the road and they are not even run in yet!

Was an epic struggle to get the old rubber off but i also noticed a few interesting things:

The rear was from 2022 and was a Continental Classic in 3.0-10 and the front was a 2014 Michelin S83 in 3.5-10. I belive the front being old and the wrong profile is likely the cause of most if not all of the handling issues. Preassures were also probably not correct, i am running the manual recomended 18psi front 23psi rear.

I will be keeping the Continental Classic as my new spare as it is still fairly new and the old spare is compromised.

My Stella has always had this squirrely feeling in any conditions. Like the wheels could suddenly slide out from under me. Scary when I'm hit by a wind gust. I have replaced the shocks and bushings. New are on their way. Still haven't had good weather to try it out. Lots of things can contribute to poor handling besides tires.

I felt yesterday. I have over 30k miles (combined) and almost 20 years (combined) of riding shifty vespas but I hit the ground hard at only 10-15 mph due to loose gravel at dusk. Pictures and story here.

My PX150 had fresh tires but the front disc when you are turning on loose gravel is hard to avoid specially if you don't see it well at dusk.

10" wheels+loose gravel+disc brake=fall and injury