Modern Vespa

Found another issue with the bike I've had for a month. I rode it this morning and turning out of my neighborhood, the steering seemed off. Like it really didn't want to go the direction I wanted. I've felt this before when the tire pressure was low, but I pulled over and checked and the tires were fine. I got back on and rode some more. The front end seemed to wander a lot and low speed steering is not as responsive as it has been. I guess it's time to check the steering bearings. With this and the fuel pump issue, I'm going to have the whole bike apart.

I think it might actually be the front shock. How easily should it compress when pushing down on the handlebars? It seems to bottom out pretty easily and makes a clunk sound. It also compresses the front some just sitting on the bike.

It sounds to me to be low tire pressure.

That was my initial thought. But the tires were fine.

What are you running for air, front and rear?

Pretty much what the factory specs are. When I bought it, the front tire was at 34 psi and it was pretty harsh over bumps. I've been running at 26-27 front and 29-30 in the rear. No handling issues at all until yesterday. My first thought went to tire pressure because I had a similar thing happen on my motorcycle when I got a puncture. But I pulled over and checked and the pressure was normal. I'd only ridden about 1/4 mile, so they weren't warm yet, but even still, I checked again after it sat in my garage and cooled off and they were at 26.5 and 30 (still the same this morning). I don't know why else it suddenly would have gotten so bad. I just rode it a few days ago with no issues. Steering feels normal to me, so I don't know if it would be the bearings. I did ride up and down my street a few times and got the much talked about wobble when letting off the throttle. Something it hasn't done any other time I've ridden it.

What are the factory specs? And where did you find them? In the handbook or the metal plate attached to the chassis?

Inside the glove box.

It's not the tire pressure. I've ridden with the pressure at the same level for a month with no issues. When I picked the bike up, the tires were pumped up too high and it still handled fine, it just was noticably harsher over bumps.

I think we need to explore this more. This is the stock shock? Are you able to capture the 'bottoming out?'

I have an aftermarket front shock, so I cannot compare apples to apples, but I do not recall it easily bottoming out.

I honestly don't know what's normal, but this seems too easy to push down without a lot of force. I've only ever had bikes with a traditional fork though. Maybe it's been like this the whole time, I can't really say. I don't see any signs that the shock is leaking, but I know that's not the only thing that can go wrong.

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I've had to replace the front shock on a 300 before now - and yes, it does upset the feel of the steering.

You will get some sag when you sit on the bike, My Malossi front shock actuates fairly easy when I push down on it with some associated clicking and noises.

How is the alignment and tire balancing? Are the tires original? Did you hit a large pothole?

Bonus points for your Vans though. Nice.

Alignment seems fine and there's no noticable wobble at speed that would make me think the tires are out of balance. Previous owner replaced the tires within the last couple years and didn't ride it much. I don't recall hitting anything. I did ride on the highway for the first time the previous ride and nothing seemed odd. I don't know. I called a shop and I'm going to try to take it in next week. I'm sure if I knew what the problem was, I could fix it, but trying to diagnose it isn't working out so well.

Do you have a top case or other container on the back?

Honestly I wish someone would say, yeah that shock is blown because I know I could swap it out without too much difficulty. Of all the things that can upset the handling, I'm not sure which one is the culprit here. I just know it was handling perfectly and now it is not. I really don't want to take it to a shop, but I also don't want to just throw parts at it until it is fixed. With the age of the scooter, it wouldn't surprise me if bushings are the issue, or bearings, or shocks... lol. But nothing seems obviously worn out to me. On my previous scooter, 2009 Aprilia SportCity 125, I had to replace the silent block bushing on it at around 10k miles (scooter was bought new at the end of 2012, so it sat at the dealer for a long time). The one on the Vespa shows some cracks when the center stand is down, but doesn't look too bad. Silent block on the Aprilia had come apart so bad it was able to be pulled out easily, so it was really obvious it needed to be replaced. I'm much better at fixing cars.

Another thing that can really upset steering is the swing-arm bearings. No, not the exhaust support bracket, but the four needle bearings that help keep the front of the engine attached to the frame. Also the 'silent blocks' can produce some vagueness.

Parts no.3 (2 off 600161) and 8 (2 off 597374) :

I do not. And no passenger. Only accessory is the short Prima windshield.

Here's pics of the silent block on and off the stand.

That looks pretty average, so doubt that's a problem. There are other silent blocks, in the crankcase, and I sincerely hope yours are OK! See:
GTS 300 crankcase silent block replacement question (solved)

Yeah, that doesn't look fun. I'll see if I can get a look at that one in the daylight. Thanks.

The most common problem by far is the needle bearings (above) giving out, either by being dry or rusting away - the factory puts eff-all grease on them, and the tubes they are in should really be filled right up with grease.

The way to test is to get a friend to hold the frame securely while you try to move the whole engine and transmission assembly from side to side - any movement at all and those bearings will need inspection.

It's possible to change out the needle bearings, but if time is in any way a factor, it makes more sense to replace the whole swing-arm (if that's the problem, that is).

Small update, but not fixed. I took the handlebar off and checked the top steering bearing. Nothing seemed abnormal there. There doesn't appear to be any binding or notchiness to indicate a lower bearing issue. I'll see if I can take the swingarm off tomorrow and look at the bearings in the rear.

Oh... and I'm a moron. Putting my tools up, I noticed I left off the plastic cap that goes on the bearing. So I get to do it all over again.

Just in case of confusion with nomenclature - are you calling the exhaust support bracket (as Piaggio call it) the 'swingarm'? 'Cos it ISN'T the actual swingarm, which is in front of the engine, not in the rear. That's where the usual suspect needle bearings live.

I really do wish MV members would stop calling that support bracket 'the swingarm' - it does sweet eff-all to help the engine 'swing', it's bolted rigidly to the engine casing.

What would Adri call it?

Guilty as charged!

GTS Swingarm, Uuuugly

It's a much wider used nomenclature than just MV members. Both SIP and Zilioni call there aftermarket support brackets 'swingarms.' SIP also lists the OEM one as the swingarm.

https://www.sip-scootershop.com/en/product/swing-arm-piaggio-right-rear_PI019030

We should probably also rename the swingarm puller.

I promise to refer to it as the exhaust support bracket from now on, in solidarity with your efforts.

Dear old SIP also call part of the front suspension 'swingarm' as well as the actual swingarm and the exhaust support bracket. Sigh.

Fair enough. Yes. Exhaust bracket. I was going off of what I've heard others call it, but I concede that's not correct.

the official parts lists always have great names ...

see part 29 Maintenance

I think I am heading in the same direction with my old 2015 facelift GTS300. It is fine on the straights, but as soon as I lean into a corner something doesn't feel right, as if the wheels are not in line.

Can't feel any engine wobble with the bike on the centre stand, and tyre pressures are ok, no loose wheels. So I suspect a faulty shock (Malossi RS24s) or those engine mount bushes. Might put the original shocks back before looking any further, as that is the easiest thing to do.

I wish I had another one to compare the front shock to (closest Vespa dealer is 2 hours away), but to me, the front end seems to compress too easily. Although with the age of the bike, there's a number of things that may need to be addressed.

I was able to get the new exhaust bracket bearing installed today. Also put the new muffler on while I was at it. I took it for a test ride and it seems like that did the trick. I may go ahead and order the Malossi silent block just to firm things up a little more, but it didn't feel like it had a mind of it's own when turning.

Nice to see you arrive at a solution after some troubleshooting. Well done and good looking pipe.

Now you need to paint that thing that shall never again be called a swing arm.

the engine swingarm one?

if looking to firm the bike up you could also/instead replace the bushings at the top of the front + rear shocks (I've done this)

I will look into that. Thanks.