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Norton Heavy Twins
1949-1975+ I'll share with you my observations, findings and opinions in the articles below.
I hope the content makes up for the lack of glossy & flashy presentation.
This page will be occasionally changed and added to, as my free time allows.
David Comeau
last updated Feb 2009

ENGINE
Norton heavy twins head evolution pictorial
1950 model 7 500cc through 75 RH-4 850 Electric Start Commando

Automatic timing chain adjuster-twin chain motors

Norton heavy twins cam profile survey added profiles

Norton heavy twin cam hardness/softness

Norton heavy twin - crank case evolution
A few pictures of the timing side - from Atlas to E-Start.

GEARBOX

PRIMARY/CLUTCH
Easy Pull, No Drag, No Slip Commando Clutch

Commando clutch packs

Atlas belt drive
No mod usually goes without a hitch, this one was no exception.

OIL/LUBE
Commando oil filter cross reference

Norton oil pump & wet sumping
Drawing of the Nortech mod (now out of business?) that was done to Frank D. oil pump and cover,
worth doing if your pump is not up to snuff. AMR may be doing this mod now.

FRAME&FITTINGS
frame#s

MOUNTINGS/ISO
The Isolastics are of interest to me, so I have finally done a measurement of the front ISO compression rates.
Front ISO rates

FRONT SUSPENSION
Atlas/Commando Forks

WHEELS-BRAKES-TIRES f&r

REAR SUSPENSION

BODYWORK-tanks-seats-sidecovers-fairings
Norton Fiberglass Bodywork

CARBURETOR/MANIFOLDS/AIR CLEANERS

IGNITIONS
Boyer Exposed The Original Boyer MK III for Norton Commando-detailed analysis originally written in 1990

Boyer Evolved Norton Commando ignitions overview Updated June 2005

Coil measurements from different types and styles new Mar 2007

ELECTRICAL GENERAL
Lucas RM24 3 phase power output curve 130k.jpg

RM 15 specs & testing

zener regulation curve

E-Start cable upgrade


MODEL SPECIFIC
Hi-Rider 1971 through 1975
Nortons answer to the chopper.....the ugly duckling of the commando body styles
74/75 red & blue stripe on white

1975 Electric Start Commando

HOT ROD NORTONS, EXTRA PERFORMANCE MODS AND EQUIPMENT, Dunstall, Gus Kuhn, Norvil, etc.

Dunstall literature