Modern Vespa

Hi all

Recently my 2011 GTS developed a stange symptom.

When I start the bike in the morning, all seems good, but when rolling the throttle, it will stall and die.

It can move forward for a while but stall when moving.

The most strange part is, after the engine temp went up to maybe 1/3 of the meter, all is good.

I have a passenger with me, if no passenger the situation seems be better, this needs more test.
(Update: when I ride alone, the situation is very minor or none)

First I thought it might be water in the fuel, but after some test I think not.

I also suspect maybe the weight of riders cause some tube to crack open, after check I noticed there is crack on my evap tube, but after I blocked the tube it's still the same.

So far I didn't see any damage or wear inside the bike.

Does anyone ever have similar problem? I don't know where to start looking now.

Thanks.

How many miles on it? Sounds like valves may need to be adjusted

It's about 60,000 KM now.

I would check the valve clearances

If it has something to do with the valve clearance I think it's because the clearance is to big, then you should heard the ticking, or?

There is some tip in the workshop manual, please see attached picture from it

This is a classic symptom of valve clearances being too tight - though it's a much more common problem on the older Leader engines, as noted in the Piaggio tech bulletins. However, ensure the idle bypass passage is clean first...

At 60,000km checking the clearances is due anyway, so might as well do it.

Thanks for all the reply.

It kinda happend overnight, not gradually, also I am not hearing valve rocker ticking sound... but I will try to check it.

It's so hard to reach valves on a GTS compare to all bikes I rode before.

Compared to many scooters out there, the valves are fairly easy to get to once you set it up right. Try working on a Honda PCX - it will take over an hour just to remove panels and such just to get to the valve cover.