Well guys here is my 2 penny worth, I have lived in Roma for 20 years and I often use my UK plate bikes here in Italy as well as in France and Spain. As far as the Italian police are concerned:

1. They are super keen on your documents. Here you should ALWAYS have your driving licence with you as well as a passport (dont forget that ID cards here must be carried at all times). You also must have the original of your bike's log book and insurance, I always travel with colour photocopies.

2. Mods like small number plates as well as tail tidies which allow the number plate to be angled upwards to avoid the speeding cameras are VERY likely to attract fines.

3. If you are stopped and fined you are obliged to pay the fine in cash, otherwise they can keep your bike!!!

Re the fines, as far as I know there is an agreement whereby if the country has a border with the country where the bike is registered (so in this case France and Switzerland and Austria) then they will send you the fine. If like the UK there is no border then they don't bother, I have never had a fine by post here.

Good luck!!!

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(Now sold on, sob) 2011 Blue XT660X with gold wheels, was 26,500 km.
Engine mods: K&N Stage 1 filter, DNA Stage 2 filter, snorkel removed, Kev fuel mod fitted.
Plus: smoked Puig screen, Yam aluminium sump guard, Yamaha / Acerbis handguards, Givi Trekker aluminium side cases, Leo Vince X3 cans plus Kev front fork mod and Fender Xtender. Just fitted Michelin Road Pilot 3 tyres.

SOLD the XTX for a Super Ten 1200. And just bought a Raptor 700 so staying on here for some tips....