ducati xr 900 flat track special 40 41

ducati xr 900 flat track special
GTS TO XR
using a croquet mallet stolen from his son, peter koren started bashing
out aluminium on a sandbag to commence this stunning ducati special
I
t took more than a couple of
glances to understand that
the bright orange bike shining
out from a gaggle of parked-up
modern Italian motorcycles at
an event earlier this year was
actually a Ducati and not a
Harley, but only a split second
to appreciate that this bike was
something very special. Luckily I
met its owner Peter Koren, and
when he started to describe how
he'd also built the bike himself
from scratch, I was left amazed.
While the Harley-Davidson XR
dirt tracker is a cult machine in
its own right, and favoured by the
late, great Evel Knievel and racer
Cal Rayborn, Peter's audacious
Ducati-based take on the XR
works beautifully - you'd think it
was a factory machine (but from
Bologna or Milwaukee?).
"It was an abandoned project
based on a 900GTS I'd bought for
spares for my 750GT and 900SS,"
explains Peter, "but though covered in rust and missing parts, it
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was on closer inspection too good to
break. I thought of building a Z-stripe
Sport utilising some parts I already
had, but then it sat in the shed for two
years while the idea of a flat trackerstyle bike came into my head."
Peter's styling cue for the flat tracker
might have come from the prettiest
of them all, but he knew straight from
the off that there was no point buying
up loads of just XR parts. "A correct XR
tank would never fit the frame. I needed brakes so couldn't run with a spool
hub. I also had a fixed, low budget as
it was a bitsa. So as a starting point I
bought a replica XR seat base and bars
from the States and began from there.
I wanted it to look as if it had come
out of the Ducati factory."
Peter's a little reticent about his many
skills, but to build what was in his
head, he just got on with it. "I knew
I'd have to make the tank myself to
enlarge the whole thing by 10% so
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I made a wooden buck, got a sheet
of aluminium, stole a croquet mallet
from my kids and started bashing.
I also realised I had to learn to gas
weld aluminium to join up the bits,
a two-piece base, two sides, one top
and the tunnel - that was tricky!"
Peter also made the side panels, like
the tank from 2mm ally sheet, in a
similar manner. "The XR doesn't have
side panels as such, so I looked at
the shape of the seat unit and the
completed tank, and also took Ducati
inspiration from my SS and GT side
panels. I also added air scoops to
break up what would have been large
slabs of bodywork. I fabricated a steel
seat pan which was upholstered
beautifully by Earl."
The Ducati's frame needed some
serious adjustment, so Peter got to
it with the grinder and oxyacetylene.
"First of all I constructed a jig from
timber and studding to fix the frame
down properly. I wanted to get rid of
Peter with his Ducati
XR that lines up in
the shed with bevel
Ducatis GT750 and an
SS behind
Details, details; how
beautifully is this
machine put together?
And consider that most
of the cycle parts were
either fabricated, made,
welded, modified or restored by Peter. One of
the best specials we've
seen, without a doubt
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43
the ugly kinks that the rear part of the
GTS frame has because I predicted
that they would push out the highlevel exhaust system I had in mind."
explains Peter. "So I cut them out and
added a gusset to mount the side
panels too. The frame still didn't look
right on the mockups, and I realised
the rake was just wrong, so I steepened it from 31 to 26 degrees. 26 is
fine, the bike steers really nicely. I cut
through all the tubes, rewelded, fettled
and filed, having set the angle on the
jig, but in the end, using the oxyacetylene was tough, and not wanting to
risk distorting the frame, I had Exactweld in East Grinstead complete the
work, and they did an excellent job."
Peter, undaunted, sorted out the rest
of the frame. "The swinging arm is
as original, but I had to add various
brackets to the rest of the frame for
the tank, coils, ignition, regulator and
other parts. I fabricated lugs at the
rear end of the frame to
accommodate the seat, and also
made a rear sub-frame to support the
seat base and rear light. I wanted to
do the job properly - I hate stuff that
when you scratch under the surface
it all turns to shit." While for most of
us lesser mortals, just the thought of
cutting and shutting a Ducati frame
would bring us out into a cold sweat,
Peter's persistence continues throughout the rest of the bike, and his eye
for detail and lines and proportions
that just look 'right' extends to the
cycle parts too.
"I really enjoyed making the exhaust.
The tighter bend under the front
cylinder came from a grab handle you
find in disabled toilets (no I didn't
steal one..), and the cheap Far-Eastern
silencers have cut-outs Imola-style for
the rear shock, so sit nice and tight to
the frame. Footrests are the original
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Peter's fine all-round
skills were essential
to building this bike.
From modifying the
frame, modelling
bucks and formers
in wood, to bashing
2mm aluminium plate
and rebuilding the
motor - he even did
the paintjob though
he hated that part!
"I hate
stuff that
when you
scratch
beneath the
surface it
all turns to
shit"
The Ducati bevel
motor and XR-type
fuel tank really sit
beautifully together.
On the road, Peter's
creation is fast, noisy
and handles like a
Ducati should...or like
an XR should? It's
agile, either way
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GTS items adapted and rear-set to
suit my height, and I made the gear
lever, and brake lever with cable that
pass under the seat. I also fabricated,
drilled and curved the silencer grilles,
using an old Conti to get the form
right. The forks are the original 38mm
Marzocchis reversed with calipers
behind the fork leg, which also gives a
cleaner look. The rear shocks are YSS,
and the wheels are Akront 2.15 x 18s,
with Bridgestone Trailwing tyres fitted.
Handlebars are from Wakula Racing in
the States. The clocks are from China,
and look ok and do the job. Headlight
is a Bates-type thing that I would
like to change at some point. I had
originally planned for no lights but an
accident on my other Ducati changed
my mind. I rebuilt the motor myself
- luckily it already had a good crank
and bearings, though the rods were
to short - hence the plates beneath
the barrels." Peter also did the painting ("My God, do I hate painting") in
Harley Racing Orange with 2K clear
lacquer, over clever decals designed
on CAD, drawn on paper then cut out
by vinyl sticker people. Future plans
for the XR900? "Better rear shocks. I'd
like to change the headlamp because
I don't much like the lip on it. And
I'd possibly like to carry out a desmo
conversion too."
Kicking the Duke over and with an
easy start, Peter makes some passes
for the camera. His creation is fast,
skinny, essential and beautiful, and
makes a sound that a proper bike
should. "I love the rawness of it, and
the way it fits me. It's so slim and
light compared to the other bikes I've
owned, though at 195kg wet it weighs
a little more than I thought. But I'm
very happy - I'd always made things
all my life, always admired the Harley
XR look, and so I just had to scratch
the itch with what I had at my disposal!" Lucky for us that he did. IM
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