Page 14 - Beep Beep April 2025

Thanks Will – I asked for projects and this is really interesting. Ed
Will Johns’ ‘little’ new project.
In 2023 I was offered the option of buying an
old Triumph motorcycle, the owner was not
sure of model or year, so I took a look and
discovered from the frame and engine
numbers that it was a model worth the effort in
rebuilding. 1970 TR6 frame (Tiger 650) and
1970 T120R engine (Bonneville). The head
fitted was from a single carb Tiger. Check out
the original photo and you can see the amount
of work needed to rebuild this old bike.
Anyway, the deal was done and I returned
home to have Toni (my wife) ask if I was going
to the dump with the old parts – HA HA!
The following is a short story on the journey.
I decided to start on the engine which was
partly complete and in poor condition (seized).
After stripping it down and releasing frozen big
ends, the job of measuring bore size etc
identified that I needed 40 thou over pistons,
and new everything else, all bearings, seals,
gaskets, cam gears, chains, plus bolts, etc.
Interestingly the threads used were a
combination of BSW, BSC, UNF, and BSF so I
needed to check with my trusty thread gauge
before ordering new supplies. It was around
1968 - 1970 that the bike industry needed to
change threads etc to suit the American
market, which was the destination for most of
these bikes.
The head is a single carby Tiger head and after
stripping down, vapour blasting, skimming the
surfaces and fitting new guides and valves it
was rebuilt ready to fit to the newly assembled
bottom end. I might mention at this stage that
a lot of the parts which came with the bike in
boxes were not for this model, so a lot of soul
searching was needed to overcome this hurdle
and source correct parts from the W.W.W. This
required careful examination of parts offered to
ensure they would fit my bike. (Triumph
changed quite a lot of parts through the last
years of the 60s. e.g. parts from a 68 are
different to those from a 70s machine).
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