Modern Vespa

I'm getting some rumble and judder from the clutch on my ET4, it's seems to be a worse when it's cold and then clears up as the engine warms up. It's fine once it's going but I get this rumbling/judder when the centrifugal clutch meets it's 'biting point'. It was particularly bad this morning (it was cold, wet and raining) - having said that it was the first time I had ridden it in the wet so it could be normal for those kind of weather conditions.

I've only had it for a month or so and it's my first scoot so I've no idea if this is normal or not.

If it's not normal - any idea what could be wrong with it?

It's a 2002, has done 22k miles and has a full Piaggio service history.

Mine does the "judder" but usually at the end of a long ride when you slow way down, then slightly roll on the throttle. I think that the "judder" is just a given with the ET4.
More concerning to me is the flat spot in the throttle when you roll it on hard at a dead stop. It's like there is a delay in the throttle response.

Yep I've noticed that too. There's sometimes a delay which can a bit worrying when your at the front of a queue of traffic at a set of traffic lights!

A least I'm not the only one with the judder though

My ET4 behaves the same way, judder wise, even after service checks and new belts and rollers.

On the other hand, the tendency of my scooter to gag when starting hard from a dead stop was taken care of when I disconnected the evap system.

I don't recognize these symptoms with my ET4. Is it possible that there's a difference btn earlier and later models somehow, or that this may show up at higher mileage? Mine's a 2005, still w pretty low miles.

Cheers,

--Deborah

Clutch shudder would have almost nothing to do with belts or rollers. It has do do with how your clutch shoes are engaging with the clutch bell drum. You might just need new clutch shoes. Your clutch springs might also need replaced. If one or two of the springs were losing tension, it could cause uneven clutch take up, which would lead to the judder you describe.

I get this from time to time on our ET4.

It was a problem with the GT200 as well.

I found that a build up of clutch-shoe dust in the clutch bell was the main culprit.

If you are handy and can remove the transmission cover and clutch bell it's pretty easy to clean.
I also run some 320 grit emery cloth around the inside of the bell, that dust can leave a 'glaze' on the inside of the bell contributing to the problem.

Failing that, if you take the round plastic cover off the rear of the transmission housing and liberally blow
compressed air in there, that will certainly help.

While you are down there it would be a good idea to check the air intake hose at the front of the transmission housing.

Make sure it isn't all blocked with crud and also make sure it's secured tightly to the housing.

I find an electrical zip tie works great.

The first time I ever had the 'judder' problem I noticed that that hose had not been re-attached correctly from a previous service,
without the airflow going through the housing the dust built up really quick.

hope this helps
-marc

Thanks for the info - looks like I'll be getting hands dirty this weekend

The dust seems to be somewhat hygroscopic, in that, when humidity is high, the judder is worse.
When hot and dry, it all but disappears. I have cleaned mine several times during the 15,000 + km I have on the clock.

I've had this on all my autos.
Strip the clutch down clean the bell remove the dust.