Modern Vespa

2007 GTV250 i.e. Battery is new and is reading 13.2v static. When I switch the ignition on the lights work, horn, indicators etc but immediately I thumb the starter button there's a loud 'crack' and everything goes dead. Any ideas guys? PS Please keep it simple - any answers should be to the level that a five year old can understand!

Did you already replace your belt and rollers?

The first place I would look is at the wire that runs from the starter relay to the starter motor. In the attached diagram, #1 is your starter and #3 is that wire. Maybe it has come loose at the starter end and is touching a ground point. Or perhaps the insulation has been chaffed and there is a bare part of the wire making contact with a ground point.

-Craig

I would try removing the starter and testing it outside of the bike.

Check your battery terminal cables. Make sure they are clean and tight. Never hurts to start with the simple stuff.

Is a fuse blowing when you try to start the scooter? Are you replacing the fuse and it just blows again next time?

Looking at your previous posts, you have done some work on the variator and valves. After it was buttoned up, did it start OK? If not, go back over what you have done and look to see if any wiring was disturbed during your repairs.

I haven't yet carried out the valve clearance check as I am still waiting for the delivery of a motorcycle lift which I ordered off eBay. On reading the responses I'm thinking that it is most likely a short in the starter motor circuit or possibly the starter motor itself. As soon as the lift arrives (supposedly today but I haven't yet heard from the trucking co) I will check it out. Just another question as I haven't been a Vespa owner for long (Suzuki Burgman before!) where is the relay for the starter please? PS Many thanks guys for all your answers, much appreciated.

Starter relay should be under the seat bucket, on the right-hand side, bolted to the side frame. It's brown, no other fuses nearby. Item #5 in the diagram below.

Starreem many thanks, just what I needed buddy.

You could have found that yourself if you'd downloaded and flicked through the manual.

https://manuals.wotmeworry.org.uk/Vespa/GTV250/

Thanks for the link to the manuals - I didn't know they existed in pdf format. Over here in the UK the only manual we have is the Haynes series, often referred to as 'the joke book'!

Every Piaggio / Vespa dealer can order manuals in paper or PDF format.

Hi Jim, Unfortunately Vespa Dealers in the UK are very nearly extinct and those that do exist are as co-operative as the Iranian Revolutionary Guard. 5 years ago Piaggio insisted that all Vespa Dealers also took on Guzzi and Aprilia superbikes and those that declined got the heave-ho. As a direct consequence the Dealership has been slashed by 75% and those that are left are extremely unwilling to help out the home mech by giving out info such as workshop manuals and wiring diagrams. As an unforeseen consequence to Piaggio, without a network of local Dealers, sales of all makes including MP3, Piaggio scooters, Vespa, motorcycles etc have slumped from 7,000 in 2014 to 1,800 total units sold in the UK market in 2018. Young people who want basic transport go to a Dealer in their home town who will sell them a Neco, Lexmoto, Sym or anything else made in China for 1/3 the price of a Vespa. So, the long and short is unfortunately we can't get the manuals you have kindly sent me the link for but I will post that on the Vespa Club of Britain Forum with your kind permission.

I've fixed it . . . . 1/2" pet pipe pushed over the frayed +ve cable. I also located a blown 5A fuse which came as a non-optional extra with the electrical short. Eventually I'll have to replace the cable but for now to keep me up and running for the rest of the riding season this will do. My better half was getting frustrated at my grump over the last few days so thanks for all your suggestions guys and for restoring a smile to my face

Good job getting to the bottom of it!

That looks like the main cable that attaches to the battery. I wonder why it was only shorting when you pressed the start button. Seems like it should have been shorting at all times.

-Craig

Hi Craig, the frayed cable wasn't right thru and as the cable had come out of the clip on the inside of the engine compartment it was rubbing intermittently on the cylinder head. I had noticed that sometimes the batt was draining in just a few weeks but assumed it might have been a weak cell. When you press the starter button you put it under max load and therefore that was when it shorted. I'm not an electrician by any means as my electrical education ended prematurely at aged about 7! However, I can't think of any other rational explication and its all burning and turning again now.