Norton Mercury 650




Make Model.

Norton Mercury 650


1968 - 70


Four stroke, parallel twin

Capacityir coole

646 cc / 39.4 cu in
Bore x Stroke 68 x 89 mm
Cooling System Air cooled
Compression Ratio 9.0:1
Exhaust Two-into-two, chrome


Single concentric carburetor, Amal


Coil capacitor
Spark Plug KLG FE75 or FE80, Lodge 2HLN, Champion N5
Battery 12V
Starting Kick

Max Power

35 kW / 47 hp


Final Drive Chain
Gear Ratios 1st 11.32 / 2nd 7.52 / 3rd 5.39 / 4th 4.42:1
Frame Single downtube, cradle

Front Suspension

Telescopic fork

Rear Suspension

Swingarm, plungers

Front Brakes

Drum, twin leading shoe

Rear Brakes

Wheels Steel, laced wire spokes
Front Rim 3.00 x 19" (USA 3.25 x 19")
Rear Rim 3.50 x 19" (USA 4.00 x 18")

Dry Weight

185 kg / 408 lbs
Colours Quicksilver and Atlantic blue / Silver and black

In 1966 a new management, Norton Villiers, assumed the AMC reins, continuing with a scaled-down but un-changed workforce, whose urgent priority was to commence Commando production. Their secondary task was to utilise, and market, the huge stock of hardware (Atlas, P11 etc) not common to the new Commando; it was from this background that the Mercury arrived in 1968. Norton Villiers, meanwhile, and understandably so, were clearly that pre-occupied with the Commando whereby upon its announcement the Mercury was allowed to be perceived as a 'parts bin' special, whereas in reality it was only a slightly more sober (single-carb) edition of the greatly revered 650SS, and with a lumpy seat!

The Mercury is the last of the Dominator twins, and the final stage of development from the introduction of the first Bert Hopwood Norton twin, the Model 7, in 1949 (or parts bin production exercise depending on your position). Production of Featherbed framed models ceased in 1968 when the 650SS and the 750cc Atlas were discontinued on the launch of the Norton Commando. The Mercury sold between 1968 and 1970 with the 650cc motor fed by a single carburettor. This one has the standard paint job with silver tank and Atlantic Blue mudguards, primary chain case, oil tank and battery box, plus the optional rev counter fitted. Being the final development it can run on unleaded, has 12V electrics with capacitor for running without battery.