Largly written and researched by Alan Yardley and members of the Ducati owners club- and frankly anything I have written is in the main
things I have picked up from DOC members!!
PANTAH OVERALL very reliable with engine overhauls being required at approx. 40 - 50K miles. Oil changes done at 1500 miles although
1000 miles is used to be on the safe side. Filters from Citroen 2CV, Sunbeam Talbot fit Service Castrol GTX, Mobil One, Silkolene Super
Four, Silkolene Pro 4, Castrol R, Morriss's 10/40, Duckhams Hypergrade, Cheap 20/50 Multigrade from supermarket. Advice about using
Castrol R has been given indicating that problems with starting are found due to high viscosity of the oil at low temperatures. Cam drive
system to be checked regularly for belt tension, pulley nuts working loose, the tensioner and idler bearings running dry, oil seals leaking.
The belt tension can be found by giving a sliding clearance to a 5mm drill bit between belt and idler bearings whilst lifting the tensioning
bearings up against the belt. Three standard bearings 7mm wide can be substituted with a washer to take up clearance.
CLUTCH slip can be eased by inserting extra steel plate, Friction plates can become hard and require replacement on some bikes well
before wear limits are reached. Clutch baskets are prone to retaining rivets on primary gear working lose. Surface grinding the steel plates
has been very successful. The larger heavier clutch fitted to 600 models can be used in earlier machines. Straight cut primaries can also be
fitted to speed up clutch rotation and raise overall gearing. Clutch shafts can break if clutch securing nut loosens. These nuts have proved to
be very difficult to undo on some engines. Some have had to be drilled to remove. Weak point on Pantahs especially when tuned.
Improvements made by using sintered bronze clutch plates and extra heavy springs. Clutch can be machined to accept an extra pair of
plates. Early "small" hydraulic clutch on 600SL has a slipping problem which can be cured with new stock fiber plates and by substituting
springs from a Suzuki GS1150. They are also found on some GS1100 models, and so appear to be readily available. They fit with just a bit
of filing. The engagement is a little more abrupt but still very acceptable, and the slip has been non-existent for about 10K miles.
DRIVE Two gearbox sprocket sizes are available 14 & 15t. The larger one is recommended to ease chain wear. DID chain recommended.
Rear sprocket sizes vary from 36 to 41. The lower size gives a higher cruising speed for less revs but reduces acceleration and pickup. 41
size enables engines to rev out in top but makes high speed cruising less relaxed. Gearbox failures on early models were quite common
due to cogs breaking and dogs rounding off. Excessive rear cush drive play can be eased by inserting slips of inner tube rubber between
cush housing and rubber spider. Mounting bolts on sprocket can be subject to loosening and also shearing off. High tensile UNF bolt
conversion has been done successfully by MOCATI of Bath.
ELECTRICS The standard Bosch ignition system can fail when the outer covering on the pick up wires breaks down due to engine oil
temperature. Continuity tests with the pickups in position can be misleading as shorting out against the adjacent pick up wire can exist and
not be detected. Resistance testing can also be affected in the same way. Pick ups are the same as Mote Guzzi V50 if second-hand parts
are required. Misfires are sometimes traced to pickup clearance problems. Lucas Rita ignition has been used with very positive results. Pick
up mounting point for this system is situated outside of the double pulley on the cam belt cover. Being a dry running system engine oil
temperature has no damaging affect. Timing adjustments can be done without having to remove alternator cover. Build quality is poor but
has been improved by making pick up plate and cover in stainless steel. Double pole coils can be substituted with the Rita. When using
strobe light to time ignition DO NOT remove inspection window from cover. Cover is under crankcase pressure and blows oil out when
window removed. Spark plugs used are NGK BP7HS, B8HS, B7HV, B8HV (available from Club) Champion plugs are generally regarded
as hopeless, with backfiring on start up being a symptom of impending failure. Magnetising of the flywheel has caused elusive failures.
Flywheel rotor mounting nut can loosen in use causing knocking noise and expensive damage. Locking washer locating area has been
machined out to fully locate washer and prevent it flattening during use. Regulator failure, (cheap modification done by using RS bridge
rectifier and Lucas Zener Diode, also replacement unit available incorporating LED functioning light.) Overcharging of battery, (larger battery
fitted by cutting clearance space into rear mudguard and flattening tray edge) Front fairing indicators on SL model are same as fitted to small
fiat cars. Cheap batteries are not recommended. Yuasa Yumicron or 'GS' used mostly. Standard Bosch headlight has sharp cut off pattern.
Honda unit fitted as alternative. Oil pressure switch can rupture internally and cause idiot light to remain on whilst engine is running. On
early models replacement switch can be used from Lucas for Volkswagen or Porsche/Audi range. Check whether thread is straight (Later
switches supplied by importer have tapered threads). Neutral contacts have this switch removed and blanked off. Neutral indicator switches
are prone to leakage through the contacts and from the threaded area. A number of machines have this removed and blanked off. Electrical
system is generally reliable. Fuses vibrate loose. Continual battery discharge cured by earthing regulator unit to frame. Idiot light failure (RS
bulbs can be used in original housings). Starter motor bushes contaminated by engine oil when seal between crankcase and motor fails,
(brushes from fiat car cut down and used). Ducati Club France has printed two alternative wiring diagrams in their magazine, translation
being done. Regulator failed at 40,000km. Rebuilt one substituted. Charge warning light remains illuminated irrespective of revs until lights
are turned on, at which point it is extinguished, irrespective of revs! Regular liberal applications of WD40 to all connections seems to keep
things reliable. Don't skimp on batteries, buy the best quality the minute it starts acting up.
CHASSIS Front suspension can be very harsh. Experimenting with different grade oils and spring rates is time consuming and expensive.
Forks can be lowered by approx. 25mm through yokes to give better steering response. Yokes from the bevel twin range have been fitted,
with packing shims, to speed up steering response. Complete 38mm front ends from bevel series have also been fitted. Fork legs and
yokes can be difficult to polish up without exposing blow holes. Standard Marzocchi Strada rear shocks are over sprung and under damped.
Alterations to give reasonable results are not easily done as the units have to be dismantled and the internal damping washers
arrangement altered. Popular substitute for standard shocks are Koni Dial-a-Rides. Fontana's have also been used. Spas mono shock
conversion done on one machine with very good results. Rear swinging arm bearings in engine are notorious for wearing out. Regular
checks are advised plus rotation of the pin. Lubrication nipple and needle roller conversions have been done, one in the swinging arm ends
resulting in less work when changing bearings. Rear wheel adjuster blocks can corrode inside swinging arm. Greasing of blocks
recommended. Outer clamps can break if over tightened. These are two different sizes with a thinner one being positioned next to the brake
calliper mounting plate. Centre stand clearance affected with this modification. Rear, and front, spindle thread size is 16mm fine rate. Crash
damage to frames in small accidents usually limited to steering stop plate lugs. Centre stand side lug can foul ground if bent. Stand can be
altered by welding plates to feet to increase clearance. Stand springs can rust and break. Stainless springs available via Club, also rear
brake pedal return spring, cable clutch arm return spring. Chrome on clip ons, gear lever, rear brake lever assembly is pathetic. Rechroming
and stainless/rose joint conversion done on one machine.
FRAME is strong in horizontal plane but tends to flex in vertical. Frame rigidity can be improved by welding gussets to all the engine mounting
points and cross bracing behind the rear cylinder. Rigidity is further improved by welding triangular plates at the bottom cross tubes at the
front of the frame to reinforce the steering head. Front end and rear wheel of a RGV 250 have been fitted by adapting the sprocket and
making up spacers and fitting axles giving better tyre choice. Rear wheel from an F1 or Alazurra can be fitted. Poggipogiani air-valve top nuts
have been fitted with double lip oil seals. Guzzi S3 handle bars can be fitted to raise riding position. Dymag wheels have been fitted. Fork
dust covers were found to provide a lot of stiction to the forks. Solution is to remove them and use suitable fork gaiters (Norton Commando,
MZ) for a substantial improvement.
ENGINE All bearings used on the machines are C3 grade of standard type except belt idlers and crankshaft mains. The mains are a wide
clearance type. These are available from bearing distributors, as are all the other bearings. Do not use cheap C3 bearings. ( C3 relates to
the clearance sizes within a hearing, it is NOT a quality specification) SKF and RHP are recommended makes. Oil seals are standard size
single lip except for starter motor/crankcase seal. This is 7mm wide (standard 8mm) Recess in housing can be machined 1mm deeper to
take 8mm seal. Double lip seals are recommended for forks and cam belt double pulley. If persistent oil leak on double pulley exists a baffle
can be inserted in the pulley bearing. Persistent oil weep from filler plug on dry clutch engine covers cured by fitting longer threaded plug
from model. Desmo shimming and carb setting print out available. Quality of alloy castings varies considerably. Cylinder head and inlet
manifolds are susceptible to blow holes. When raced hard little ends can break off. Over revving can cause cases to crack near the bottom
pulley at the oilway to the front head causing oil to pump out. Repair by removing bearing carrier, bore through oilway and fit a 8mm cap-
head bolt. This pulls crack together and is sealed with suitable glue/sealant. The bolt is then drilled to re-establish the oilway. Crossland oil
filter code 673 can be used. Big bore kits can cause reduced compression ratio and negate their CC advantages if attention is not paid to
the combustion chamber machining. Post 84 750 crank and pistons can be used for a conversion but the crankcase mouths have to be
opened out. 750 crank is considered to be better for this conversion than the 650 Alazurra crank due to the better balancing factor. Only later
Pantah cases are suitable for a big bore conversion as they are considerably stronger. For a breather a standard plastic flapper valve from
an automotive power brake vacuum booster (available at any auto parts store) can be used and run the outlet overboard. Appears to work
just fine, except for the following issue: When the crankcase level is filled up to the "max" line on the sight glass, a lot of oil is blown out the
breather (or somewhere in that area, it's hard to pinpoint the source). This problem goes away if filled only to the "min" line, and a leak-down
test indicated good health.
TUNING Engine tuning is expensive and can make the bike unreliable. Mez Porting are the acknowledged experts for gas flowing. Valve
guide wear can be high when larger valves are fitted due to standard guides being short. Longer guides have been made and installed.
Standard valve seats will accept a small increase in over-size valves external oil supplies to camshaft bearing blocks fitted to cure persistent
leakage from internal supply O ring. Extensive modifications to engine can be done. Large valves (inlet from 750 Monjuic) and gas flowing
produce good results without impairing reliability. CC capacities above 498cc available are 583, 598, 612, 640, 650*, 680, 750*, 850*, 920*
(* = longer stoke crank used). 650 engine from 650 SL and Alazzura regarded as desirable. Crankshaft on one F2 racing bike has been
modified by cutting flywheel and alternator rotor part off, and rebalancing. Removal of flywheel enables engine to build up revs quickly.
Alternative ignition system required. Engine tickover of 6000 rpm on the F2 bike. Oil cooler can be plumbed in by routing line from oil
pressure switch tapping in crankcase (10mm x 1.0mm) through cooler and into camshaft bearing blocks. Restricted line can be extended
from cam feeds to supply oil directly to gear selector drum via tapping on rear of crankcases. Internal oil feeds to heads blanked off by dowel
in feed drilling of barrel or head. This method cools oil to heads only. Complete engine cooling is done by having clutch cover modified to
accept tappings coinciding with oil pump outlet drilling and crankshaft inlet housing in cover. Internal oil passage in cover is ground out and
blanked off by welding. A restricted by pass line can be installed between the supply and return lines to give instant oil supply to crank on
start up. Later 750 type crankcases have double tappings to accept cooler as standard, MOCATI engine oil temperature conversion fitted to
one bike using sender unit tapped into oil strainer plug.
WHEELS & TIRES Pirelli Phantom, Avon AM20-21, Metzeler BT 45. The Avons are not well regarded in the wet. Standard 110 rear size can be
increased to 120 but can cause handling problems due to larger cross section roll radius. Tubeless tyres are NOT suitable as FPS wheels
are not designed to accept them. Wheels are regarded as heavy but strong, with the gold finish very difficult to remove. If crash damaged can
usually repaired by Alf Hagon. Later 3 spoke pattern as fitted Alazzura have been used. Wire spoked wheels from Yamaha TZ250 have been
adapted to fit. New wire wheels are available (very expensively) via Newton Equipment.
BODYWORK Quality of original panels is poor. Crash damage usually causes severe splitting due to high filler content. Tool compartment
base in seat of SL model can loosen and fall out. Pattern fibreglass fairings for early type SL are reported as not available. Later MK2 type
exist also Twin headlight version available from Waffen Fibre(WF) Full twin headlight fairing available from Sprint Manufacturing. Full racing
NCR pattern fairing to fit standard frame available (WF) 900SS half fairing has been used. Fibreglass front mudguards in three styles
available plus fibre rear mudguard.(WF). One machine has had seat restyled by recovering allowing extra room for passenger and vents
moulded into rear shock absorber bulges. Tank sides can touch frame and cam belt cover. Rubbers used on engine have been used on top
of mounting rubbers to avoid contact. Extra fuel capacity can be obtained by removing central air filter housing and cutting away bottom of
tank and reworking. Flush filler has been fitted to one bike. Plastic lever on petrol tap can snap off. Taps from Paso fit although no reserve
available. Alloy F2 tank can be fitted but is 5" longer than standard. NCR style fibre tank is available. 500SL colour is roughly the same as
Porsche Helibua. Fairing can be supported by fitting a Hailwood replica type brace. Modifications to improve the look of the rear of the bike
have been done using a ford transit tail light and Renault indicator lights. Airtech has dual headlight fairings for Pantah SL's on their
BRAKES Some bikes suffer from very poor brakes whilst others have no problems. Small calliper bikes are improved by using large master
cylinder from later model and bevel series. Modifications to improve standard system include Goodridge hoses, Teflon calliper pistons,
stainless calliper pins, discarding front splitter unit and doubling brake hoses to master cylinder, bleed nipple at master cylinder banjo bolt
(ignition key clearance problems when using this), drilling hole to link cavity present at calliper joint to hose entry. Brake pads recommended
are Brembo soft compound, Ferodo,EBC, Vesrah (available via the club). Failure of the friction material has been reported due to rust forcing
material off backing plate after machine has been used in bad weather. Regular checks are advised. Brake discs rust overnight and can
contaminate pad friction material. Poor brake performance has been improved by soaking discs with acetone to remove grease and oil
contamination. Cadmium plating of discs has been done to stop rusting. Regular checks advised on disc surface condition and size. Some
discs are very close to minimum tolerance from new, making remachining difficult. Extensive drilling has been done to lighten discs on one
machine without adverse effect on reliability. Existing holes can be opened slightly. Radially drilled holes in outer edge of disc have been
used to lighten and create turbo cooling. Noise from rear brake when bike wheeled slowly is caused by calliper mounting plate vibrating,
cured by a small wooden wedge on one machine! Permanent cure found by floating the calliper with mounting arm attached to crankcase.
BRAKES & FORKS of discs seems to cause problems with contamination of the friction material and significant decrease in braking
capacity. Original brake hoses caused very spongy lever. Goodridge hoses provided much better feel, but very hefty squeeze required to stop
hard. Suspension Original Marzocchis very harsh on bumpy roads and started to leak after 35,000 kms. Replaced with Bitubo shocks with
fully adjustable preload (threaded collar) and damping. More compliant but probably not worth the high cost. Front forks filled with 225cc of
10wt fork oil rather than 185cc as per handbook. Much improved damping. Works Performance gas shocks have been fitted with good
results. They also list shocks for a number of old Ducatis on their website.
EXHAUST Standard system is double skinned, heavy, restrictive, and difficult to remove. Internals of silencers deteriorate rapidly. Balance
pipe and front pipes can corrode together and make removal very difficult. On one bike brackets on balance pipe have been removed and
resited using spacer washers between bracket and engine casing. Internal crossover tube in balance pipe can be blown through to remove
restriction to exhaust gases. Alternative systems: 2 - 2 Standard with silencer ends cut just after last baffle 2 - 2 Standard with silencer
internals removed (loud) 2 - 2 Stainless 'Armours Ltd'(disaster) 2 - 2 Conti 'production system' 2 - 2 Waffen Fibre Carbon fibre end cans. 2 -
2 Swann open meggas (racing) 2 - 1 Roberts stainless long front pipes 2 - 1 Conti 2 - 1 Verlicchi race pipe (scares old ladies and
Christians!) 2 - 1 Verlicchi front pipes/ Waffen fibre carbon end can 2 - 1 Gianelli 2 - 1 GM race pipe (very poor fit) 2 - 1 Harris (loud) 2 - 1
Harris alloy end can 2 - 1 Theresby RH exit (very poorly made) 2 - 1 Hejira (chronic!) 2 - 1 Yardley large bore anti reversion special (unusual!)
2 - 1 F1/Matchless standard silencer! Gianelli 2-1 was fantastically loud and sounded great on over-run but changing to Conti 2-2 sport
system produced a deeper, resonant note and seemed to improve smoothness throughout the rev range. This might be psychological
though, those Conti stampings on the pipes do funny things to you! Contis are still available brand new in Australia but are expensive. Stop
them rusting by inserting a cup of old engine oil each long trip. You look like a 2-stroke for a couple of miles but the oil coats the internals
and keeps the bank manager happy. Cam Belts If the bike is left inactive for long periods the cam belt bearings can seize. The ultimate
effect is a broken belt due to friction between the belt and the seized bearing. At low engine speed the impact was nil. At high engine speed
the impact is not worth thinking about. Squirt of WD40 on the bearings upon re-starting the bike seems to prevent seizure. Big engine killer
is incorrectly tensioned belts. Steel pulleys are recommended as replacements for the earlier alloy/plastic pulleys.
STARTER MOTOR Bushes wore out in 29,000kms. Replacements have to be soldered in place. Ducati replacements expensive but fitted
easily. Starter also made horrible squealing noise which was found to be faulty bearing on the shaft. Solution was to drill and tap a hole in
the end cover to accept a small grease nipple. Be careful not to overgrease. Condition thought to be the result of water ingress.
Fuel Tank Later Pantahs with removable fuel cap allow ingress of substantial water which rusts the bottom of the tank. Solution is to treat
tank with chemical liner and regularly drain.
Ignition Ignition pick up wires can cause problems and are best replaced with Teflon coated or oil/heat resistant wire.
Gearbox Second and fifth gears can blow but others seem to last forever. Primary gears have good life. Pantahs after frame number 660901
had a fifth gear ratio altered from 1:0.9 to 1:0.931.
Instruments Replacement speedos can be found from Honda 550 K3 and 750 F2 but are a little optimistic in their readings.
Carbs Transmission snatch below 3500RPM can be cured by filing out the cutaway on carb slides by an eighth of an inch if air screw
adjustments don't cure it. 40mm Dell'Orto pump jet carbs can be fitted if replacement manifolds are made up. K & N filters and ditching the
airbox is a popular modification.
General My Contribution Ignition Volt drop from battery to ignition units was found to be high (2.3 Volts) when start button pressed. This
caused unreliable starting as ignition would only fire on release of start button. Cure was found by adding relay to switch directly from the
fuse box to the ignition units. Result was a volt drop of only 0.2 volts and reliable starting even with a half dead battery. Due to regulator
system, battery discharges even when ignition is off. Without replacing regulator the best solution is to remove earth battery lead when
leaving bike standing for more than a few days (cheap) or use a battery charger suitable for permanent connection (£45). Electrical
connectors are rubbish and have all been replaced by quality crimps fitted with a ratchet crimping tool. Fuse box corrodes badly. I found out
that my bike is on it's third fuse box. If it looks like happening again I will replace with something of higher quality. Koni dial-a-rides found to
be under sprung and over damped (I'm 15 stone in battle dress. Front fork preloader tubes cut to 135mm. 200ml of 20 grade JP1 oil used.
Piston, bore and stroke choises Now, to resume the complete matter, since I have already considered all mix-matches of parts (and as yet
done none) and a friend has fitted 82 mm pistons to an Alazzurra 350 (BxS=62x51):
1) All Pantahs were created with only three crankshaft strokes: 51mm, 58 mm and 61.5mm
2) All Pantahs were created with identical lenght cylinders, so they can all fit the same belts.
3) Pantah pistons came in 62 and 70.5mm bores for the 51mm crank; 74 and 80 mm bores for the 58 mm crank and 82 and 88 mm bores
for the 61.5 mm crank.
4) All Pantahs have the same conrods (900cc NOT included), so big ends and small ends are identical in all engines: on the conrod, on the
shaft and on the piston.
5) any Pantah cylinders will fit in any Pantah crankcases, with the only relevant exception of early SL500 cases which require their specific
6) the standard combinations of shafts and pistons will give capacities of 350, 400, 500, 580, 650 and 750 cc
7) the above features and apparent interchangeability will tickle the fantasy of home tuners who are already imagining an 88x51 super-short
stroke Pantah 622cc
8) unfortunately, being the cylinders all the same length, the pistons of shorter stroke engines must be longer than those of longer stroke in
order to reach the head. Exactly half-stroke-difference longer
9) therefore, a piston matched with a crankshaft of shorter stroke will give a greater squish height; a piston matched with a crankshaft of
longer stroke will hit the head. (e.g. if an 82 mm bore piston coming from a 61.5mm stroke motor is fitted to a 58mm stroke motor, the
squish band will be 1.75 mm higher)
10) all Pantahs were created with three types of heads: one with small ports and a small dome, which was fitted with 30.5 and 33.5 valves
and coupled with the 62 and 70.5 bore pistons, one with medium ports and a medium sized dome, fitted with 33.5 and 37.5 valves and
coupled with all other pistons and one with big ports and big dome, fitted with 36 and 41 mm valves, coupled only with the later version of 88
mm pistons (F1B)
11) this means that if you fit a different piston-cylinder pairs to a certain Pantah engine without modifications, not only squish height will be
affected but also squish band width, compression and valve-to-piston clearances.
12) if on the other hand you shorten the cylinder to adjust the squish heigth but you retain the standard head, you might end up with the
compression ratio of a diesel and the belts will be too long and will stay loose.
13) it is possible to fix compression values by machining the heads and/or the piston domes and belt tension by elongating the belt adjuster
hole, but at this point the camshaft will have rotated a few degrees. when machining the piston domes you will probably also have to
machine the valve grooves.
14) you can still machine a new groove in the pulley to re-position the camshaft with the correct angle, but at this point you will have:
shortened the cylinder; machined the head and piston dome; modified belt adjuster, machined the belt pulleys and perhaps re-balanced the
crankshaft and fitted bigger valves and seats. Your mix-matched motor will at this point have costed you more than a bigger, standard motor
(Alazzurra and Elefant 650 are cheap and plentiful).
The early 500s (those with the "banana" fairing) had smaller holes in the 'box to accomodate cylinders, and the cylinders had accordingly a
smaller outer diameter in the part that fits in the 'box. The holes were enlarged to accept the 600's bigger bore cylinders and the modification
was standardized on all Pantahs, including the 500, 400 and 350. This mod went more or less along with the new stronger "3 dogs"
gearbox so if you have the old motor you will also have the weaker gearbox According to the Pantah's part list (available at ducatimeccanica.
com) the "old" cylinders and gearboxes are on motors nos. 600001 to 601653 and 602238 to 602528 while the new gearbox was fitted to
motors from no. 603246 onwards My Pantah 500 has motor no. 600508 so it has both of the old things. ciao Luca 750cc in a Pantah. Just
what combination of parts will I need to make a 650 Aly into a 750 motor? I just checked in the manual, the Aly has an 82mm bore and a 61.5
mm stroke. >Does this mean that I can bore out the liner and drop in a set of 88 mm pistons? (Discounting the Nikasil liners or course) Or
do I have to find a set of barrels from an F1? both options are possible. F1 (or Elefant-Indiana-early modern SS) cylinders will fit without
mods. >Will the heads still fit? Would the crank have to be rebalanced. Can I Changing 650 into 750…. do this on the cheap? F1A had the
same head as the Alazzurra so F1A pistons will match the standard head. Not F1B pistons. The Alazzurra was already under-valved as a
650 so imagine as a 750!
RECOMMENDED READING Write Ups
- Classic Bike - June 1998 750 Pantah in Verlicchi frame. Dymag wheels etc. Mmmmm nice.
- Classic and Motorcycle Mechanics - No. 105 July 1996
- Adelaide's Docteur Desmo big bored and tuned Pantah. Useful tips about frame bracing and common pantah engine faults.
- Motorcycle International Classics of the 70s and 80s - Summer 1989 Write up on standard 500 SL Pantah. General buying advice.
- Classic and Motorcycle Mechanics - No. 128, 129, 130, 131, 133, 135 Series of articles about restoration of a rather sad looking 500SL
which turns out to have been bored to 600. Covers full restoration cosmetic and partial mechanical but not in a lot of depth.
- Classic Bike - Jan 1998 Standard 500SL mk1 owned at time by Baines racing. Complementary write up on well maintained bike. Excellent
- Books Brooklands Books - Ducati Gold Portfolio 1978-82 Articles published at the time the Pantah was released. A good read. (11 Pantah
articles out of 41 total)
- Mick Walker - Ducati Twins Restoration 240 pages total with good detail photos of bikes for getting that restoration just right. Model
technical specs, carb and shimming details. (Pantah 350, 500, 600, 650 XL, SL and TL covered) Mick Walker - Ducati Buyers Guide Full of
model photographs and gives good historical and model development information.
Other Pantah's and Cagiva's
Place a 750 motor in a 500 Frame
Scan to bottom for lots of information
Engine specs (650)
Bore 82mm / Stroke 61.5mm / Capacity 649.5cc
Compression ratio 10:1
Max power 56.5HP @ 8400 rpm
Max torque 40.5 lb. ft. @ 5750 rpm
Max engine speed 8900 rpm
VALVE TIMING -612549 +612550
Induction before TDC 40° 39°
after BDC 70° 80°
Exhaust before BDC 67° 80°
after TDC 43° 38°
Operation and clearance of tappets, cold motor condition:
Engine specs (500SL)
Bore 74mm / Stroke 58mm / Capacity 498.9cc
Compression ratio 9.5:1
Max power 45HP @ 9050 rpm
Max torque 40.2 Nm @ 6300 rpm
Max engine speed 9500 rpm
Induction before TDC 50°
after BDC 80°
Exhaust before BDC 75°
after TDC 45°
Operation and clearance of tappets, cold motor condition:
Intake and exhaust opening rocker arm 0.10mm (0.0039″)
closing rocker arm 0.00%0.02mm (0.00%0.0008″)
The bike is an '87 model and came with the 38mm Brembo calipers and 2.5"/3.0" x 18" cast wheel combination. It was purchased by
the previous owner in February 1989 from Monroe Motors in San Francisco. Emile rode the bike on the street for a bit, and then started
roadracing it in the AFM 650 Twins class. I met Emile in 1990 and did some work on the bike, setting up the squish bands and making
clipons. Emile raced the bike in pretty stock trim, other than adjustable Konis, 38mm Marzocchi forks (stock was 35mm) and 280mm
aluminum carrier discs in place of the stock 260mm one piece items. In 1991 he had a local tuner clean up the ports and manifolds
and do a valve job. I think Emile got as high as 4th or 5th place finishes before putting the bike back on the street at the end of the 1991
season. He had a couple of mild low slides which left some minor dents in the tank, but destroyed the stock fairing.
I got a call from Emile in late summer 1992, when he decided to sell the bike. I'd wanted a belt-drive Ducati for some time so I bought it
in moderately rough condition. Emile had complained about how the front end pushed in corners at Sears Point, so I didn't bother riding
it before taking it apart and putting the frame on my frame jig. L-twin Ducatis have always had a problem of being tail-heavy (I raced a
GT750 for several years in the early 1980's), and I figured this, in conjunction with the massive rake/trail, was causing the front end
push. I cut off the motor mounts and moved the engine forward in the frame 1.5". Since the swingarm moved forward with the engine, I
lengthened it about 1" to keep the wheelbase near stock. I also steepened the steering rake to 26 degrees, and installed triple clamps
from a big Guzzi to reduce the trail from the stock 5" to something in the 3.25-3.5 inch range. I made boxed-in motormounts, removed
the vertical tubes that ran just behind the back cylinder, and added in another 5 triangulating tubes on either side of the frame, a
triangulating tube between the top rails under the seat, and a bit of streamline tubing between the lower frame tubes above the
I put an aluminum plate on top of the frame (under the tank) and mounted all of the electrics to it, after removing the various safety
interlock devices and redoing much of the wiring harness. I don't run a steering damper, and have never had the front end shake on me.
Rewiring and figuring out how Emile had attached the Honda switches (crudely) took about 12 hours. I added mounts to the steering
head for instruments/lights. I removed three of the six spokes in the one piece rear disc, and milled the disc edges until the surface
was no wider than the brake pad. I then made a floating carrier for the caliper. While messing with the rear wheel I converted it to 520
chain with an anodized aluminum sprocket (and slightly higher gearing). Rearsets, a slight reangling of the intake manifolds, Malossi
bellmouths on the stock 36mm carbs (with the accelorator pumps removed), a 2-1 pipe with a proper design and headpipe by my friend
Craig and a hydroformed curved megaphone and trick aluminum header clamps by me, and the adapting of the center stand mounts to
bolt to the motor (since they weren't attached to the frame anymore) pretty much completed things. A set of Avon AM22/23 (110, 130 x
18) in track compound and number plates saw me ready for the 1993 AFM season. The bike weighs 390 with lights and a bit of gas.
Great Britain's Ducati Owner's Club
Issue #131 - Pantah Experience -
"Hints & Tips"
Written by David Richardson