its own in straight-line speed. But when it gets to the bumpy bits, a modern machine,
with suspension travel seemingly measured in yards rather than inches, will show the
older RN the way.
“They rode differently in the old days,” says Burling. “The bikes had relatively short
wheelbases, and the RN has a very short swingarm so it’s hard to keep the front wheel
down. They would lift the front a lot more, and steer with the throttle and rear wheel.”
The RN’s suspension gives travel of around 165mm (6.5inches) up front and 120mm
(4.3inches) at the rear, and ground clearance is a modest 195mm (7.7inches). The forks
are Suzuki works, with the finely machined sliders and fork damper pistons fitted with
dual fibre rings – the leading technology of the day.
On this machine, a pair of period Ohlins shocks has been added to the back end. Like
the European works bikes, the RN has roller bearing swingarm mounts in the frame to
eliminate binding as the rear suspension moves.
Despite being mounted in sexy full-width sandcast magnesium hubs, the brakes
were not powerful, and the 130 x 28mm single leading shoe front and 150 x 28mm
single leading shoe rear took a while to slow an RN400 down when it was hauling.
There were also problems with the alloy rear sprocket bolts working loose and cracking
the magnesium hub. This was solved by lapping the bolts in like a valve on a four-stroke
engine, and going to Allen heads, which enabled the mechanics to get more torque
on the bolts.
What Suzuki gave its chosen riders in New Zealand was a blisteringly fast and smooth
motocrosser that handled far better than its contemporaries. Importantly, the RN put
its power to ground effectively, and its super-light weight meant the riders were able
to maintain their fitness and speed for the duration of the race.
The suspension of the day meant it was never going to be the greatest bike when the
going got rough, but it was still way better than the competition. It may well be that
character flaw that saved this important, almost historic, RN400.
As soon as the mighty RM370 came along, the RN was uncompetitive and unwanted.
It avoided a pitiful descent through inexperienced riders and mechanics, becoming
rougher and more bodged with every race until its heritage was lost; the bike becoming
worthless and eventually discarded.
This is one of the few to survive, but this has only been possible thanks to the skills and
commitment of Messrs Senn, Burling and Franklin.
KIWI RIDER 39