Dear Claire,
I've got exactly the same bike. Identical in every detail to the early
TR1, except with a 750 engine and some Japanese advice on the chain
cover and tool box. I also have the 5E5 engine number. There may be
some differences with the starter motor and oil filter compared to
the TR1.
My bike was imported from Japan about 8-10 years ago. As the bike is
quite old I use Lancaster insurance which covers the bike for around
£100/year.
Watch the exhaust as replacements are hard to come by.
Unfortunately, I used the bike in all weathers and over 25000 miles in
a year. The bike suffered. You may be able to get some MPH clocks from
breakers or XV Motors in Addlington.