RUST magazine: Rust#7

Adventure
based on that original
race engine and that
meant that despite the
addition of a balancer
shaft, it still vibrated
like a road worker’s
jackhammer.
Such vibration could
have been seen as a
weakness, but in fact the
motor was built strong,
with a roller bearing
crank, needle bearings
to the con-rod and
bronze bushings through
the top end. Oil capacity
was a healthy 2.1-litres and with two Eaton oil pumps this
Missing in
Adventure?
meant oil changes could be extended to 5000km (3000 miles),
and many owners would extend that! The competition origins
of the motor weren’t totally hidden, like many hi-compression
singles it struggled to pull cleanly below 3000rpm and would
need to be wrung out to 8000rpm to find max power of around
49hp (the red line is 10,000rpm), which with a wide-ratio
five-speed box would be about 105mph - if the vibes hadn’t
defeated you.
Ready to Roam
If KTM’s enduros were ready to race, the big 640 was certainly
ready to adventure. The giant tank - with a 700km range - was
perhaps the biggest attraction for many. But as well as that