Ducati 750 GT
1974 Ducati 750 GT Custovation Diary
1974 Ducati 750 GT Bevel Head
Special Report by Joe in Dallas for webBikeWorld.com
Volare Senz' Ali
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1968 Royal Enfield
During my years of riding, restoring
and collecting vintage British and European bikes, I fell in
love with four distinctive vintage marques.
The muscular engineered Vincent Rapide; the gentlemanly smooth
Ariel Square Four; the petite and potent Velocette Venom thumper
and the Ducati 750 V-Twin, an Italian blend of engineering,
power and seductive good looks. Iíve owned 3 of the four with
the Vincent being out of financial reach.
Each machine materialized from the minds of great designers.
Phillip Vincentís HRD-Vincent, Edward Turnerís Ariel Square
Four, John Goodmanís Velo Venom and Dr. Fabio Taglioniís Ducati
bevel drive V-twin. All share common attributes of distinctive
style, power, sound and engineering excellence for their day.
Sadly, three of the four have passed to oblivion but Ducatiís
legacy of efficient and practical design lives on in the GT1000
SportClassic, the grandson of the í74 bevel drive V-Twin.
This diary captures the high points of finding, owning and "custovating"
a 1974 Ducati 750GT. Custovation is my word for customizing
and renovating the build of a one-of-a-kind vintage motorcycle.
The custovation captures the heritage of the early 70ís bevel
drive racers and adds some modern and personal touches to make
the bike reliable and safe ride at speed, while maintaining
the head-turn factor. This diary is a completely selfish act
to preserve the details of the 750 GT custovation events that
took place before, during and after with the notion that it
inspire or guide others to develop their own custovation project.
In the Beginning
The project bike, a 1974 750 GT
was purchased in 1997 from a Norton club friend and he acquired
it at an estate sale.
It sat in his garage for two years before the need for more
room encouraged him to sell. The bike was about 95% complete
and in fairly good condition since the Texas climate and the
storage inflicted minimal damage. After acquisition, it sat
in my garage for 5 more years, waiting patiently for the start
of the project.
During the waiting time, some missing bits were purchased.
A lot of tinkering about personal preferences, color schemes
and technical issues were noodled around in the gray matter
design room between my ears. For inspiration, a montage of Ducati
bevel drive V-twin pictures was hung on the shop wall serving
as a project compass pointer. Thatís the day the flag dropped.
In my mind's eye, I was able to clearly see what the bike should
do and how it should look.
The Custovation specs called for a style taken from the genes
of the cafť style bevel drive V-Twins but without the lay-down
riding position. Ace style bars and a mono-posto seat with a
bum-stop add to the look. Stock engine performance, new suspension,
ignition and modern front disc brake system take care of the
go, handling and stopping chores.
Oh yeah -- it should also borrow the colors that made the
1974 750SS forever famous.
The project was divided into two stages; the frame and all
its associated components including electrics and then the engine.
I learned the hard way that itís better to break a long project
into manageable chunks. That way, tasks are smaller and have
a defined start and finish along with a logical fit with other
assemblies of the project. Motivation is fueled when you see
steady progress, while the expenses are stretched out.
Before any work was started several information sources were
consulted. A collection was made of downloadable manuals, article
reprints, picture gallery and parts sources from around the
world. Bevel Heaven offers additional information and their
parts inventory continues to grow. Various hardcopy reference
books were useful too and theyíre listed at the end of this
article. Most can be found on the net or from bevel drive specialistís
In February of 2002 the motor was started
for the last time before the take-down.
The rationale: if the engine runs before itís taken apart,
I know it will run after I put it back together.
The removal was very easy and the engine was set on a dolly
until the rolling frame was complete. I imagined a gleaming
rolling frame with all parts fitted, anxiously waiting for the
engine. Just the kind of inspiration needed for an expected
The speedometer showed 35,000 miles and the Smithís instruments
appeared original, so itís very possible the reading is accurate.
Compression was low on the front cylinder and fair on the
rear. Someone fitted a Dyna ĖS electronic ignition so a good
battery and a squirt of oil in the cylinders, helped get it
No blue smoke so maybe the guides or valves are not worn.
The answer to that question will come later. Even in its weakened
state the neighbors confirmed that the old bevels drive V-twinís
bark sounded awesome without silencers.
Disassembling the bike down to its major component parts
was easy and in a few hours there were several boxes of parts
organized and tagged as needed, so three months from now Iíll
be able to recall where that weird bolt is supposed to go.
Tiny ferrous metal chips are a tough to remove from the magnetic
rotor. Left in place they can cause major damage to the stator.
So as soon as the alternator cover is removed from the bike,
cover the magnetic rotor with plastic wrap and tape into place
-- this will keep any ferrous chips and debris from collecting
on the rotor.
Examination of the removed parts revealed the tachometer
to be broken, sprocket and chain completely worn, tires while
showing deep tread, felt like wood instead of rubber. I had
to cut them off with a hacksaw.
Wheel bearings either
worn or seized, stock Scarab caliper seized, J-model master-cylinder
a useless insult, front wheel bearing spacer worn, swing arm
spindle rusted, front fork seals leaking, carbs in need of rebuilding,
air cleaner plastic box disintegrated, front and rear brakes
worn out, Lafranconi silencers more at home on a Guzzi, frayed
cables, outdated shocks, the electrical system showed the tell-tale
signs of being tinkered with in the past 28 years. Tape balls,
green oxidation and extra wires sprouted from the loom.
Several days were spent cataloging replacement parts and
their estimated cost. Pills and meditation had little effect
to lower my blood pressure, as the estimated price tag for the
parts was revealed.
This step is like having a colon exam. You volunteer to have
it done but all the time itís embarrassing and no fun at all.
So orders were placed, checks were written and bank accounts
were emptied. I kept telling myself "This is the
price to pay for custovating a vintage bike".
With the easy tasks behind, it was time to get serious. This
is the part of the project thatís labor intensive, so no matter
how much time you estimate it will take, it will take longer.
inspiration, I wanted to get something pretty in the garage
faster than you could say pasta primavera.
This is where paint and polish gives an adrenalin rush and
accolades from your friends. The frame had some rust and grainy
After a valiant effort to strip the old paint and remove
the rust, I gave up and a professional sand blaster removed
all traces of rust and old paint. Best money spent.
The steel frame and trim parts had the ideal textured surface
for paint adhesion.
The painter was already on board waiting to receive the blasted
parts for primer. The colors, decals and trim scheme were worked
out ahead of time so he knew what to do.
While the painter was busy, parts cleaning and polishing
started with a vengeance. Polishing aluminum is the dirtiest
job on the project but it yields the best rewards. For the next
few days my nose sneezed out more aluminum oxide dust than a
smelter but the end result produced alloy parts that gleam like
Only the kick-lever, gearshift, rear brake lever and stay
arm will need a trip to the chroming vat. All rough finish cast
aluminum parts get a trip through the blaster. After blasting,
I usually go over the castings with a stiff stainless steel
brush to bring out a long lasting dull but resilient patina
The stock spokes were painted silver, with thoroughly rusted
nipples. If you rebuild your own wheels, remember to photograph
the lace pattern. Measure the hub offset before cutting off
the spokes. I forgot that on the rear wheel but confirmed with
others that in fact the hub is centered on the rim.
the parts orders arrived and the alloy jewels emerged from buffing
wheel, theyíre collected in boxes designated for reassembly.
Having the majority of the parts in-garage before the build-up
starts makes the workflow resemble an assembly rather than start,
stop, wait and repeat again.
Surprisingly some of the stock hardware was not rusted due
to what appeared to be heavy nickel plating. Big pieces like
spacers and large nuts polished up very nicely from a battleship
gray to a bright finish.
Throughout this custovation, every fastener was replaced
with stainless to the extent possible. Bolts, nuts, lock washers,
lock nuts, and locking nuts, including the engine cap head screws.
Stainless wants a smear of anti-size compound on the threads
before assembly to prevent galling. For appearance and longevity,
stainless canít be beat. Buying stainless hardware from a wholesaler
is about one tenth the cost from a hardware store but not as
Build-up: Frame Parts
The paint scheme follows
in the footsteps of the 750 Super Sport, blending the distinctive
silver-gray background with duck egg green. I wasnít interested
in building a SS replica, so while the frame is drenched in
green; there is no fairing, clip-ons or rear-sets.
The stock steel tankís voluptuous shape begged to have the
side panels painted green so the new die cast DUCATI emblems
would have a place to contrast. The fenders were painted in
the same style with a green stripe down the center. The side
covers sport vintage Ducati eagle logs and everywhere where
green and silver meet, a fine black stripe defines the transition.
Wheel lacing was a gift from my Dad. He showed me how on
bicycle wheels, when the dinosaurs roamed the earth. Iím no
expert so I work slowly and it comes out right.
There is nothing like lacing stainless steel spokes to a
Borrani rim fresh from the buffers kiss. Itís a beautiful sight.
During assembly, wear cotton gloves to minimize fingerprints
and sweat deposits and use the oil provided, to prevent the
nipples from galling.
long while back, I made a simple spoke wheel truing stand that
looks homemade but gets the job done. After the wheels were
built, Avon Super Venoms with new tubes were mounted easily
and look good. In the hubs, the wheel bearings were either seized
or grinding, so all bearings were replaced with sealed units.
To keep the racer appearance the stock rubber foot pegs were
replaced with knurled pegs with a clear anodized finish.
The Marzocchi front forks were next. The leading axel fork
legs have an exotic look. Cleaned, polished and with new seals
and caps, the cast Ducati logo proudly shines on their sides.
The swing arm spindle seemed snug during the take-down. However,
when it was removed and the rust cleaned away, it shrank, causing
the swing arm to develop enough play to cause concern about
A new spindle solved the problem and modem shocks with chrome
springs connected the back of the swing arm to the frame.
The stock banana seat was in good condition but I wanted
a cafť look. I had it reshaped and covered by a local custom
car upholsterer. He cut down, then built-up the foam to produce
the classic shape of a bum - stop seat. The custom fit cover
has DUCATI embroidered in black on the back panel.
A used stainless chain guard was acquired and polished to
cover a low maintenance O-ring chain running on new steel sprockets.
The voluptuous gas tank required new rubber isolators and
water-pipe neoprene foam insulation coved the backbone to give
the tank a cushy place to rest. A large O-ring secures the tank
to the frame nubs
This 750 GT came from the factory fitted with Lafronconi
silencers. They were too quiet for my taste and lacked the SS
look, so Bubís Conti replicas were fitted. Theyíre not Contiís
but are half the price and look and sound just as good.
Dr. Taglioni figured that one disc brake was enough to stop
the 750GT with a stock engine and Iím not one to challenge his
genius. However, this bike is from an early production run and
was fitted with a solid rotor.
To add some style, I drilled a curved pattern of large and
small cooling holes in the disk. The Scarab caliper was seized
and parts no longer available. So a bolt-on Gremeca caliper
fed by a Brembo master cylinder-switch-lever combination was
If you have an opportunity to refit the master/caliper combination
on any bike, be sure to check sources so the two pistons and
travel are matched for braking performance, otherwise youíll
have a very poorly performing break system.
A Ducati Monster clutch hose completes the front stopper
system. Bleeding the dry system was more trouble than expected
but a Mighty-Vac solved the problem.
The original pair of 30 mm Dellíorto carbs was rebuilt and
K&N filters added to prevent anything but air from visiting
the inside of the combustion chamber. The crankcase breather
is also capped with K&N.
The bars are Ace clubman style turned up-side down to relax
the seating position and fitted with new electrical controls
and tacky black grips. During the Build-Up, plastic bottle caps
are taped to the bar ends until the grips were mounted because
I almost ripped open my scalp with the bike on the lift.
The rebuilt Smiths instruments looked like new with the intention
to keep them that way for as long as possible. Prior to about
1970, shock and vibration failure must not have been a concern
because this type of instrument secured directly to the mounting
bracket, which was bolted to the triple clamp.
After that, various types of shock mounting were employed
to keep the innards of the clocks from self-destructing. The
stock Aprilia mount goes the other direction and uses a comprehensive
isolation design, hence the big, ugly pod. After 1970, Triumph
and BSA instruments were fitted with rubber cups. That type
of mounting appealed the most to me since theyíre readily available,
reasonable price and they fit nicely into the fabricated instrument
To hide the backside of the instruments and add a bit of
modern sleek, a AGIVI A-200B smoked mini-windscreen visually
pulled together the headlight and instrument package while adding
a stylish wind deflector for the rider.
Wiring posed its own array of challenges.
For the most part the brass connectors were oxidized but otherwise
sturdy so cleaning was only a wire brush away.
Since my electrical functions were a bit different than stock,
some wires were removed or added to the harness. Marine grade
multi-strand wire is the best choice for this type of application.
More strands mean more flexibility and that translates to connections
that wonít break apart.
A modern style integrated horn, headlight beam selector,
turn-signal switch was used in place of the worn out Aprillia
switches. The Brembo master cylinder has a more reliable micro-switch
to operate the brake light so the pressure activated switch
All new wires were tape wrapped or sleeved for abrasion resistance
and maintain a clean look. The final step was a live electrical
test with the battery connected. What a great feeling to see
the lights work and voltage show up at the proper places, the
style and character of the bike shown through!
The headlamp assembly used the stock headlamp since al halogen
would add more drain to the weak charging system. Mounting the
headlight shell was a delicate matter of looks and proper fit.
Be aware that the clearance between the forks and gas tank is
limited, so the new aluminum Tomeselli like support brackets
Turn signals are Lockhart Short Stalk-Vís. The rears are
mounted near the shock tops while the fronts are mounted in
the headlamp brackets.
The stock horns worked fine but looked large and out of place
here, so an aftermarket single unit with chrome face was installed,
more for looks than sound power.
One of the more difficult tasks involved the layout and appearance
of the instrument / ignition key / indicator lights. I wanted
the key conveniently located next to the speedo, tack and the
two indicator lights (turn-signal & high-beam). The stock
instrument pod is large and ugly.
So the remedy was a custom cut and polished aluminum plate
that mounts in the same place but brings the instruments closer
together and tilts them toward the rider.
Cutting the plate is actually very easy, but there was a
lot of pre-cut fitting, measuring, guessing etc. Cover the plate
with wide masking tape to protect the surface while marking
and cutting. The end result turned out to be a very good match
for the polished clamps and chrome bars.
The voltage regulator and connector panel were cleaned, tested
and painted. Thereís a lot written about the weak charging system
on the early bevel heads and itís all true.
The best solution is to replace the rotor and stator with
untis from a late 90ís ST-2. However, thatís also a thousand
dollar plus fix. With the guidance of Willy Gonnasonís expert
advice and engineering, I opted to rebuild the regulator with
modern semiconductors and install a LED charging indicator.
This works well for me since the majority of my riding is during
The original ignition switch was damaged, so a new small
automotive unit was wired in but moved to the new instrument
panel for better access.
The switch is compact and since it has only three positions
switching options are simplified. Off, On Ė with all but the
headlights powered and the other On- adding power to the headlights.
750 GT Engine.
A previous owner, installed a Dyna-S ignition, but kept the
stock coils. One coil was found to be open when the start-up
A replacement was used then but for about the same
price, modern matching high output Dyna coils were installed
ensuring a healthy 30,000-volt lightning bolt to zap the gas
A homemade aluminum bracket tucks them smartly under the
gas tank with outputs pointed down. Resistive plug wires are
from NAPA and plugs from NGK.
The battery is a slightly larger capacity 14 Amp Hour unit
to ensure enough power for the bike. The battery compartment
base was lined with a piece of spongy doormat material so the
battery bottom wouldnít chafe on the metal mount. Large
O-rings or rubber bands cut from an inner tube work well as
The rolling frame with electrics was finished, so the engine
INSPIRATION. Thatís whatís sitting in
The parts are mounted, wiring harness connected and tested
multiple times. Yeah, I even shut off the shop lights to see
what she looks like during nighttime ride. The complete rolling
frame is ready for the engine.
First things first. Since the true condition of the engine
internals is unknown, cleaning was a good place to start. That
way, if the bottom end and gearbox are ok, that portion of the
engine will be ready when the top-end rebuild is complete.
Itís easier to clean the outside of the cases with the top
end installed but the huge glob of congealed electricity (read:
aluminum) is clumsy to handle.
The bottom cases are scrubbed with carb cleaner, Simple Green
and S-100. Use either a stainless steel or hard plastic bristled
brush but not brass. Brass leaves a yellow patina thatís difficult
All the smooth case pieces will have their oxide veil removed
and replaced with a brilliant mirror like finish after the buffing
wheel plants its kisses. A nice surprise was hiding on the bottom
of the engine -- the factory case seal was still in place, saying
that no one has been in there for 28 years.
Removing the heads was easier but the cylinders were stuck
and didnít release when the heads were removed. Squirting some
WD-40 down the cylinder stud holes and applying some propane
torch heat and soft mallet to the base immediately released
Be careful where you strike, so the fins donít break off.
The sticky culprit was a rust build-up right at the place where
the stud exits the case. The rust made a bulbous deposit that
held the cylinder from easy release. I suppose that condensation
and external seepage under the stud nut allowed the water to
do its nasty work on the stud. I spritzed a little WD-40
and held a big magnet next to the glob while scraping. A stud
remover tool was used instead of vise grips prevent tooth bite
damage to the studs.
Anxious to understand why the front cylinder had low compression,
revealed that the lower compression ring was stuck solid in
the piston. The smallest trace of rust was acting like barnacle
glue. The rear piston assembly, looked good and both bores while
shinny had no scoring or notable ridge.
The piston bodies appeared to be in very good shape with
little carbon buildup. The first try to remove the stuck ring
simply didnít work. Freezing, then heating and oiling had no
Then Syd of Sydís Cycles suggested heating the area behind
the ring on the thick inside of the piston with a lot of propane
heat. That did it. Picking at the ring made it break into several
pieces leaving the piston unharmed. That was ok because the
prime concern was for the piston since fresh rings were in the
re-build plan anyway.
In the end, it was a waste of time. Measuring the allowed
wear parameters of the pistons, bores and rings confirmed that
first over pistons with matching bore are needed. That confirmed
that the engine very likely has 35,000 miles on it. With that
expensive fact in mind, new valves and guides were also fitted
to refresh the top-end.
Cleaning the heads and cylinders involved bead blasting.
Thereís a lot of debate on this cleaning method. Some say hidden
grit will immediately kill the engine. Grit is bad for sure.
On the other hand, my experience has been ok in the past.
My drill is before blasting: 1) degrease the entire thing then
dry; 2) Wire brush clean the sensitive mating surfaces of the
head; 3) Tape over the cylinder bores and various cavities and
holes leaving only the fins for blasting; 4) After blasting,
clean with high-pressure air followed by a thorough second degreasing;
5) The raw casting can then be either steel wire hand brushed
to bring back a hard finish with bright patina or final cleaned
with S-100 and a stiff non-metallic brush for a softer finish.
Since the engine cases were not split, two internal items
needed sprucing up. First, both sludge traps were cleaned. A
small butterfly impact wrench works best to remove the slot
head screw caps on the crank. There was plenty of packed-in
carbon / metal hiding in those holes.
Using a dental pick and solvent sucked by a shop vacuum,
emptied them out. Second was the sump and gearbox sludge removal.
Kerosene poured in the cylinder holes and oil filler hole worked
like a charm. Actually the process was repeated several times
until the drained kerosene is mostly clean. A small rag on the
end of a parts grabber went inside the oil and filter holes
to move things around and eventually soak up any excess kerosene.
clutch case bearing was replaced and cover polished along with
the alternator side cover.
The gearbox selector case was opened and cleaned and re-packed
with molyĖgraphite grease. These three cover pieces play a big
role in defining the beauty of the Bevel Twin engine, so no
polishing effort was spared.
The side stand wasnít used so the engine stud was removed
and replaced with a suitable length engine case bolt.
About this time, the top end parts list was made up and shopping
started. I should have had the paramedics standing by when the
first quote came in. I figured it would be expensive but when
the prices came in, my blood pressure dropped and my vision
went white. This of course is perfectly natural reaction unless
youíre Bill Gates. I had just crossed the Rubicon with this
project. Thereís no stopping now, especially when itís just
money posing as a roadblock.
The ignition points housing was polished in-place to not
disturb the gear timing. The steel bevel drive tubes looked
like two rusty drainpipes so they were replaced by an anodized
set from Dr. Desmo.
Both carbs were given a full cleaning and polishing with
fresh rebuild parts. Cables are replaced and the choke junction
box was freshened up. The choke plays a critical role to make
for easy starting.
Guides and valves were replaced along with all the head bearings.
The left side bearings were replaced with sealed units, with
the exterior side seal removed to boost valve train oil pressure.
The cylinders were bored to the first oversize and mated
with beautiful looking JE Pistons. They have a shorter skirt
and taller dome than the stock pistons. That taller dome should
raise compression just a tad.
Putting it Back Together
The engine top-end is
a puzzle of engineered aluminum and steel but now itís time
to assemble the bits.
A temporary assembly was made first
to see the main parts fit together and measure the valve to
rocker shim sizes before fully mounting them.
cylinders were installed on the engine cases first but without
the pistons. However, before that, the case-mounting surface
was cleaned and the stud holes de-burred to ensure a flat mounting
The stud holes had crud living inside, bits of alloy, steel,
rust and oil grunge. A small magnet, dental pick and high-pressure
air cleaned the holes like new. Anti-seize was applied to the
Before installing the gaskets, notice that the front and
rear gaskets are cut to match the case holes. Get them reversed
and you can kiss the engine good by.
Pistons were then mounted on the connecting rods. The small
end bush was lightly roughed up with emery cloth. My clips had
no tang to grab so installing them was a pain.
A test fit of the cylinders and heads, revealed one of the
rear cylinder fins cast below the exhaust port was a bit too
long and made contact with the cylinder fin, when the head was
mounted. The cylinder to head joint does not have a gasket,
so the head seal depends on the machined metal-to-metal joint
for a seal.
It looked like a manufacturing flaw since the neighbor fins
where cut down for clearance. Maybe Giuseppe the inspector had
a bit too much Chianti for lunch that day? Some grinding
shortened the fin and made the seal tight.
New bearings were installed all around in the heads for a
rocker to valve clearance test. Note that the four rockers are
identical but can interfere with each other if not installed
correctly. The rocker springs need to be opposite of each other
to properly center the rocker on the cam. Check that the rockers
are centered on the valve stem. Both of my exhausts were off
by .012, so additional shims were needed to get them centered.
With new valves and re-ground seats, new valve caps were
needed. Thereís no screw adjustment on the early 750 GTís, only
fixed space caps. Measure the gap with a stack of feeler gauges
to determine the gap of interference, then, order caps that
are thick enough to grind down to the correct valve clearance
When measuring, make sure the cam is seated next to the bevel
bearings otherwise the measurement will vary and the caps wonít
fit. I replaced my old Vernier calipers with a digital readout
unit for about $30. Best investment ever, and the only way this
job can be done.
Installing the built up heads takes some consideration. I
was momentarily stalled because it wasnít immediately obvious
how the front head fit. All the books and articles written about
rebuilding the Bevel Head only talk about installing the rear
head. There are no details about front head installation.
Installing Bevel Heads
Here's the drill:
Align all the engine gear dots. That's TDC for the rear. Mount
the rear head. With its cam and gears installed (with its dots
aligned) its at TDC already. Fasten it down to 30 ft lbs.
Then take the front head: with the rockers removed, install
the cam and vertical drive, aligning their dots. Snug tighten
at this time. Rotate the cam so the lobes are at 4 and 8 o'clock,
(that's TDC for the front) then mount on the cylinder. It fits
right in. Fasten head bolts to 30 ft-lbs. Then install the rockers,
mount the cam bearing support. Secure the cam nut lock washer
Setting the proper torque for the head bolts is another dilemma.
Torque spec is 30 ft-lbs, however, thereís no room for a conventional
socket-end torque wrench. Only an open-end wrench works. Having
no other alternative, I practiced to get the feel of 30 ft-lbs.
I clamped an old bolt with nut in the vise and tightened with
the torque wrench then the same with the open-end. A few times
back and forth and I think I got a feel for the torque needed.
At this point the engine was finished enough to mount in
the frame. The side covers were not installed yet since theyíll
get in the way. Mounting the engine is a breeze -- three bolts
and thatís it.
Light at the End of the Tunnel!
A genuine simulated
gold link O-ring chain made sure those Italian ponies make their
way efficiently to the rear wheel. The drive chain on bevel
drives has a tendency to score the engine case so this was a
good time to fit a Case Saver form Bevel Heaven. Mind the instructions
to locate the saver in the exact spot. When itís there, the
chain has a clear path above the cast alloy housing.
I removed the DellíOrto chokes to simplify the engine layout.
I learned that for easy one kick starting the choke is needed.
The original setup uses a square metal box as a junction place.
My cables were worn and I didnít want to locate the choke lever
on the handlebars, so I used an Amal 2 into 1 throttle connector.
The cables were replaced and an Amal choke lever located under
the right side of the tank. And guess what? The bike starts
on the first kick now!
Adding the freshly polished alternator and clutch side covers
was like jump-starting a flat-line heart failure. The bike seemed
to pop to life. Not a full, hop off the table jump, but the
kind that makes the paramedics grin when they know the patient
took their first step toward a new life.
Finished at Last
It was about this time the 750
GT acquired a new name: The Texas Duke.
The first start-up of the Duke was a momentous occasion.
I made this a family event since my infinitely patient wife,
Beverly, and our family of sons, daughter, grandchild and their
spouses, all have an interest in riding. They all appreciate
fine vintage machinery and art in their own way. So one Friday
evening we assembled in the garage for the Dukeís dťbut.
There he sat a dandy in alloy polish splendor. Sporting new
pistons, rings and valves, along with modern technical refinements
like electronic ignition, fine Italian brakes from Brembo, the
SS like paint job, stainless everything that can be stainless
and tires from the land of Avon.
He was welcomed back into the world of two wheel motor-sports
with a hearty SALUTEí! We toasted fine red Italian wine
from the vineyards near Bologna while Andrea Bocelli sings in
the background. This small but faithful group of Italian motorbike
lovers cheered, Benvenuto a la Duke!
He cleared his throat of fresh oil and Lubriplate. Another
kick and he roared back at us just as I expected him to. Loud,
authoritative and commanding a presence in the garage, Iím The
Duke and Iím BACK!
What a beautiful Bevel Head -- a sight and sounds to behold.
Just like seeing your kid receiving a college diploma. All the
hard work and expense paid off, cigars were lit and smoke rings
filled the air.
One more toast, to Dr. Fabio Taglioni. Heís gone but his
spirit will remain an inspiration to Bevel Head lovers and the
► 750 Bevel
Head Rebuilding and Restoration Tips
Some pointers that may save you time and effort rebuilding
a Bevel Head
Ignition timing (with Dyna-S Ignition)
ē Indicator light
ē Piston Stop tool
ē Degree wheel and wire pointer
Rotate engine to just before top dead center - the exact
distance is unimportant, then screw your tool into the cylinder
head, unlock the locknut and thread the rod down until it touches
the piston crown, relock the nut.
The important part is to stop the piston going over TDC,
then place your degree disc on the crankshaft and fix up a pointer
in the normal manner. Next turn the disc to where you think
it should be, again accuracy is not all that important at this
stage, next turn engine so that the piston is hard up against
the rod of your TDC tool.
Now look at your degree disc, say it reads 42 degrees BTDC
(before top dead center) make a note of that figure, now turn
engine backwards until piston rises and contacts the TDC tool
once again. Holding in hard contact look at degree disc, this
time say it reads 18 degrees ATDC (after top dead center).
Now comes the interesting part, add your first reading (42
degrees BTDC) to the new figure (18 degrees ATDC), resulting
in 60. Now divide 60 by 2 and you have 3O degrees so still holding
engine against the stop move your degree disc to read 30 degrees
ATDC, to check if you are correct, rotate the engine forward
again until the piston contacts the stop and check the disc
- it should read 30 degrees BTDC.
Next, remove TDC tool and turn engine till disc reads 0 degrees;
this will be true TDC. Easy isn't it?
But just in case, another example: Engine contacts stop at
61 degrees BTDC, turning the engine back the other way stop
contacted at 33 degrees ATDC. 61 plus 33 = 47 degrees. So set
the disc to 47 degrees ATDC to check, rotate the engine backwards
and the reading should be 47 degrees, BTDC.
Remove tool and set engine to 0 degrees as indicated on the
disc. As will be seen by the above, the action of holding the
piston hard against the stop from both directions removes any
inaccuracies due to the various engine clearances. This results
in a true TDC impossible to reproduce by other methods.
Note: For beginners, the Ducati Bevel drive twin runs backwards,
so don't get your BTDC and ATDC confused.
Rear Brake Cable
To ensure smooth rear brake return
action, make sure the foot lever cable point is lined up with
the frame cable stay. The cable should travel in a straight
line out toward the rear wheel. If not, heat and bend the foot
lever cable lever to line up. Next I used a rubber coated cable
clamp large enough for the cable to pass through. This was located
the left silencer mounting bracket. It keeps the cable running
straight for about 10 inches.
Rear Brake Light Switch
The switch thatís mounted
on the cable is useless and not easily removed. I replaced its
function with a universal rear brake light switch by drilling
a small hole in the foot lever cable lever for the spring to
attach. The other end is mounted using a rubber cable clamp
to the frame tube holding the silencer bracket.
My bike had been sitting unused
for more than 6 years. I left the clutch alone during the rebuild
waiting to see what it needed once it was road worthy. Sure
enough, even though the slack adjustment was correct, the clutch
slipped under acceleration.
Examining the steel plate and friction plate stack, the thickness
was greater than 1.19 inches per the wear spec so I assumed
it wasnít worn out. The friction material showed that the surfaces
appeared glazed but not from use, rather something was on the
So I washed them in solvent. Very risky but I was sure it
wouldnít hurt the material and not leave any oily residue like
kerosene. Sandblast the metal plate with 100-grit aluminum oxide.
Place the plates on a flat metal surface while blasting to prevent
warping then replace the springs with a heavier coil than stock.
Valuable Ducati Custovation Resources
Bevel Drive Twins and Ducati Restoration Books
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