1968 Dunstall Atlas
David Comeau updated April
2008
General Dunstall background
Project Background
This picture below, was taken at the British
Motorcycle Meet in April of 1981. 13 years old already. It is the original
blue gelcoat fiberglass. The little tail section cubby hole cover missing
at this point. I will be trying to restore it to this cosmetic appearance/style
as it likely left the factory. The bike is now in the process of
restoration. A full series of measurements will be performed to verify
it's specifications.
photo courtsey of Calvin Vitale, owner of the bike at that time.
Now a year later, in spray can metallic green, this image was
taken at the 1982 INOA Bar Harbor Maine rally. It was said to be an extremely
fast bike, and was noted for it's tire smoking burn outs. The engine
internals are like so many pieces of polished jewelry. Very
impressive! Concentric Amal carbs and points/coil ignition. F&R 19"
Boranni rims. Exhaust has balance pipes. The large diameter Rickman single
disc brake was one of the types used by the Dunstall racing effort in 67-68
seasons. Probably much more of a real brake than the Dunstall dual disc
show pieces. It's nickel plated frame is seen already in rusting blisters.
Photo courtsey of Jeff Santere, NENO member & 1982 rally participant
ENGINE/PRIMARY/GEARBOX
head
A look down the intake ports
these are 32mm ports but the valve pocket porting is not the same
as later combats.
The springs looked like S&W type and were
heavily shimmed. Stock keepers, the inlet valves were 63gm. VS 71gm. stock.
Exhaust was a PD part#, running in bronze
guides.
rockers
left side rockers
Almost hard to believe the level of craftsmanship, I have seen some modern
attempts to duplicat these, that are pale in comparison.
pistons
>Found to have .090" above deck GPM pistons, #
734 DUNSTALL. The rings were slightly worn and would have been OK,
but I had new rings and put them in. this would make the compression close
or above combat commando levels.
cams
Dunstall Trivia-cam profiles
Dunstall cam -PD04ZC >This
cam profile is in my Dunstall atlas, it is shown advanced, exactically
as installed in the engine. This same profile was also
in my hot rodded 71 commando (Dunstall equipment).
Dunstall cam-PDR2 Believed to
have come out of a later 810 commando, roller bearings and pressure oil
feed to lobes.
lifters
The lifters upon inspection looked reasonablely OK, except for the
fact that the lightening process left a weak area. This area is between
the hole drilled and the slot, where it is at it's thinnest. ALL 4 lifters
were cracked at this point. The norton lifters are 73.3 gm. and the modified
ones are 69.0 gm. It doesn't seem to be worth lightening the lifters if
they can't take the strain. After all the cam is not that severe.!
Dunstall modified lifters
primary, clutch and gearbox appeared to be stock norton
CYCLE
swing arm
>Before
>Now ready for stripping of the nickel/chrome
plating. After stripping, the top front chain guard holder will need
repairing due to the chain damage.
After
Cyanide stripped TOTALLY clean of all copper,
nickle and chrome.
Then top front chain guard holder was repaired
Next, I had tig-welded up about 12 major rust
pit areas on the right hand tube, and ground and filed back to flush.
Additional 2nd pass of about 8-10 additional
welded areas, ground and filed back to flush.
The swing arm was then submitted to Bay State
Chrome (now out of business or under a new name) for plating only.
The swing arm is very nice.
frame
>Before
>Shown here is the bare rusty frame. The broken
tabs for the oil tank and head steady need to be repaired.
The broken tabs were repaired.
The frame was submitted to partial sand blasting
in a cabinet.
The extremeties could not be reached.
MOLEING...is what I call the rusting runners
under run the original nickle/chrome plating. When sand blasted, the chrome
nickle eventually breaks open exposing the rust. The rust has expanded
up and away from the steel tube, since rust is larger than it's steel
base metal origin. Sandlasting breaks open the moleing and leaves a pit,
edged by razor sharp flaps over the cleaned out rust pits. A fair ammount
of the center part of the frame was cleaned. Cleaned pits being the result.
Some of the frame tubes were blasted and some
were not. Much moleing was left. My sand blasting attempt was not
thorough, so an expensive but a completely effective cyanide strip was
decided on, similar to the swing arm strippping.
After
Unfortunately the FRAME didn't get the stripping
and cleaning of the swing arm.
The frame was found to NOT have been cyanide
stripped as paid for, since there was still evidence of old residual chrome
and the moleing that I was desparately trying to get rid of. $600 was wasted
with this disreputable company.
wheels
>Below is the 19" rear Boranni rim
showing the unconventional cross 1 pattern. Nortons usually used a cross
2 pattern.
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