[punyXpress]

Yes - on the inside.
Tried the infil bolt & that goes straight in so hole is bigger.
Tank bolt didn't go in & didn't try too hard in case any thread was damaged. Not sure if alloy is tougher than cheese bolt.
It's probably cheaper for Mr Suzuki to tap all holes than to only do 'S' ones.
Some silly b had just filled tank so it was starting to seem - time for a brew & ( temporarily )abandon task.