Old Bike Australasia - June 03, 2018

we had with the right angle drive. We worked out
that the shaft inside the right angle drive had the
same spline as a TZ750 sprocket, so we proceeded
to pull the shaft apart, cut the box up, we made an
extension off the gear cover on the left hand side so
it had an outrigger bearing, so we used the original
shaft with two new housings and that gave us the
sprocket on the engine. Then I had to build a swing
arm for it that was wide enough, because we had to
run the sprocket very wide, to miss the gearbox. That
was made out of chrome moly, super strong, and we
then ran TZ Dymag magnesium wheels – or the
spoked wheels, depending on the weather. The rear
shocks are the aluminium body and finned Koni 76V
shocks, 5-position adjustable internally, which you did
by taking the spring off and pushing the shaft to the
bottom to adjust the internal damping mechanism for
rebound and compression.
“It (the factory kit) was a very comprehensive kit.
Crankshaft, con rods, pistons, a twin-plug head,
camshafts, exhaust system, carburettors, hydraulic
clutch, clutch springs, magnesium oil filter cover. The
twin plug head Yamaha partly made with their
Toyota 2000GT technology. It was an all-new head
with 10mm plugs, the original plug was 14mm. Two

plugs were side by side but you had to run each from

a different ignition system. They supplied side draft

Mikuni/Solex carbs, 40mm, sleeved back to 36 with

the effective venturi 34mm. They had big long bell

mouths, and long intakes like a 6 or 4 cylinder car,

under-bucket shims in the head. I ran 11.5:1

compression, 100 octane fuel, two base gaskets to

get the correct compression, XJ650 ignition as per

factory spec. For Oran Park and Bathurst we had a

small single phase generator on it with total loss for

the last race. The race crank was a couple of kg

lighter, with special con rods, and bigger con rod

bolts. Forged high comp pistons, very thin 1mm

compression rings, standard oil rings. The kit came

with Mikuni/Solex Weber style carbs, they worked

quite well but the bike was very hard to start. I didn’t

want to run them because on that type of carb the

float runs side to side so when you turn a left corner

it leans off and when you turn a right corner it

richens up. For me that was a big problem but Greg

was happy to run that at Bathurst and we had no

problems. Because we were running a TZ750

countershaft sprocket we had to change the middle

gear (primary?) so Yamaha calculated what we

needed and made me a set of new middle gears, I

told them first gear was too low so they made me a

high ratio first gear to make the gearbox a bit closer,

but apart from that the gearbox was standard. Part of

the factory kit was a bigger oil cooler. It got very hot

if you idled it but in operation it was OK. It was still

1100cc standard so had plenty of fin area. Brakes had

to be standard from the era, but in the day Yamaha

brakes were the preferred brakes because they were

300mm, Suzuki and Kawasaki were only 280. They’re

terrible now but in the day, they worked very well.

RIGHT Making it two wins from as many

starts, Pretty powers to victory in the

1981 Arai 500 at Bathurst.

LEFT A shot that graphically illustrates

a diminutive jockey on a big bike;

Pretty on his way to victory

in the 1981 Coca Cola 800

at Oran Park.

Taking shape.

Undercoated frame and

wheel components.

The restored XS11 made

its public debut at the

2018 International

Festival of Speed and

drew crowds all

weekend.