I rode from bilbou to home last year on my 1995 916, made it 2400 miles trouble free until the rectifier failed 90kms from le havre so it was a recovery truck all the way home.
Done it this year on a 1 month old cbr600rr without issue but even that suffered from the heat.
I would pay special attn to the cooling system, perhaps a manual fan switch would be prudent, also a spare rectifier.
I would try and avoid france's built up towns where overheating will occur.
wish i was coming with you, cant wait for my next trip
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