Modern Vespa

my GTS suddenly cuts out and wont crank over!
next morning it cranks and starts!

Intermittent issue happened more than once - where do you think my investigation / diagnosis should start?

Check both brakes levers activated the brake lights.

Toggle the kill switch on and off a dozen times.

Along with the kill switch, check that the HT lead is securely fastened to the spark plug. These tend to wear over time and can cause similar issues.

Replacing the boot at the end is actually quite easy and not very expensive.

Other culprit might be the starter relay.

I have that issue - 2007 GTS250. It is the kill switch in my case. So far I've always gotten it to start, but I've been pretty worried at times. I have a new switch on hand and just haven't replaced it yet.

Thanks all for the tips!

Ive had a sneaking suspicion that it could be the kill switch as I have had to replace the horn switch previously and its the similar type.

If you can hear a ticking from the relay would the forum agree that the kill switch and the relay are OK and that the starter motor could also be included as the problem?

Anyone have any ideas what may lead the starter relay to fail?

cheers - its so good to get some clarification on this!

You could just cut the wires going to the kill switch and join em together.

If you can hear a click from the starter relay then either the starter relay has high resistance contacts (unlikely, as they'd probably fuse together) or the starter motor connections are suspect - including the the possibility of worn out or stuck brushes. If this is intermittent and sometimes it starts, then this scenario is even more likely.

But as always, it could be something else...

You could remove the starter and see if it has engine oil in it. The o-ring seal on the starter can fail and let oil mist into the starter which buggers it up.

great stuff all and thanks for the tips!