Modern Vespa

strange behavior of MP3 on the road. on smooth asphalt everything is fine. on a small rut, when crossing markings, any carelessness the motorcycle starts to behave unpredictably. some kind of uncontrollable. the steering wheel is very difficult to hold and you have to reduce speed. any thoughts, what could it be? my first thought was about bearings...

Sounds about right.

The MP3 is not built for handling except on near perfect roads.

Little tires and crappy stock suspension are the main culprit.

Putting in new adjustable Bitubo rear shocks was the best improvement I ever did to the MP3.

Make sure you run good tires for best performance, such as the Michelin City Grip

Hi Lokofunt
Echoing and expanding on sbaert's notes, I've taken the Mp3 on some large road trips across some very rough roads. Here are my observations.

It is absolutely not an ADV bike, but it can handle some surprisingly rough roads just fine with the updated suspension.

The rear shocks especially affect the stability of the bike and how it feels on rough bumpy roads like the mountain and farm roads around my area. The rear shocks on my 2016 Mp3 had to be upgraded to "Malossi" rear shocks to regain stability and comfort. It rides like a whole new bike with greatly improved stability on rough roads.

If you can find them, Malossi or the Bitubo are worth while upgrades for the Mp3. Especially if the roads you like to ride are bumpy or rough surface. The bad news is these upgraded shocks are hard to find for older model Mp3s.

I'll go to the service tomorrow, that's what they'll say, I suppose. But this is 100% not a suspension feature, but a malfunction. Silent blocks or bearings.

What's a silent block?

i do not know which one. for example https://www.pedparts.co.uk/product/8712/silent-block-piaggio-mp3-400500

Ah, bushing.

From what you described in your original post, your problem does not sound like bad bushings

Are you sure you didn't mean "the notch"??? It is a very common mp3 problem resulting in twitchy steering

bearings?
On a flat road, it is perfectly controlled and no problem. a little worse coating and a scooter becomes uncontrollable

What is the service history on the bike?

Specifically, were the headstock bearings retorqued and greased when the bike reached 1k km? And were they regreased thereafter, preferably every 5k km but no longer than every 10k km?

The headstock bearings are the grief of every mp3 due to many reasons.

Primarily, the bearings were not torqued correctly at the factory. Second, Piaggio uses a shitty open bearing design allowing dust, dirt and water ingress. Thirdly, the bearing service were often overlooked by dealers resulting in unhappy owners and costly bills.

Fwiw, Piaggio never improved the design in almost 20 years. Goes to show how little Piaggio cares about its clientele.

Quick warning - I greased my bearings about 5k. At 12k, it started to feel notchy. Luckily I had the extended warranty and it is being replaced, so I wonder if I just had a lemon or if you need to regrease at an interval more frequent than 5k?

Imo, that first retorque and regrease at 600mi/1k km is super critical to have long lasting bearings.

If you skip it, you're almost guaranteed to have issues.

I also regrease another exposed bearing nobody talks about. The ones on the steering shaft. Overkill? Perhaps, but mine is a winterbike that sits in the cold, rain and snow year after year.

Inexcusable to use such as a dumbass nickel and dime design on such a expensive bike.

I don't hear of issues like this on other 3 wheelers such as the Yamaha Niken or Tricity. Oh wait, those are properly engineered machines. Never mind.

why do you still own a piaggio product if they are so poorly designed and constructed?

Because it was cheap and at this point it is just a winter beater.

Having said that, the maintenance and upkeep costs on the mp3 are more than all my Hondas combined

Great help from the stellar contributors in here, as usual.

If I may add my own experience - the MP3 is also utterly allergic to low tire pressure. I recall when I bought one the previous owner had let the tire pressure go down a lot, and on my way home on a quite bumpy 60mph stretch of highway, wow, it became a bronco and I started to wonder what I got myself into.

After that, with the right tire pressure... you can't expect it to behave like a sporty bike, it's way too heavy and the suspension travel is way too short, but set up right for your weight (especially the rear suspension) it is actually raw but all in all it stays true - and that double tire front gives you confidence in situations you'd trust no other bike. I once lost the front on a turn when it was wet with leaves on the ground and a lady walked her dog across the intersection... I'd gone down bad with any other bike, and the bike might have slid into them... but no issue with the MP3, it gripped again up front and we did brake just fine.

Highways here in California are downright awful for motorcycles, but while the MP3 buckles, it also gets out of situations other bikes can get very dangerous in (like when a front tire gets trapped in one of those semi-trenches construction teams leave behind).

That said, I think mine came with upgraded rear suspension, so my impression may be influenced by that.