Motorcycle Restoration Projects
Oggy’s Norton Commando Fastback
This beautiful Norton was born of a blend of parts, but does have matching engine and frame numbers. ‘Oggy’ has been a Norton fan from his teen years, when Manx Norton engines were invincible, powering two- and four-wheeled racers.
The ‘Commando’ moniker was applied first in 1967, but the canted-forward air-cooled twin traces its heritage back to the late-1940s 497cc overhead-valve Norton Model 7, designed by Bert Hopwood.
This basic design grew to 600cc, 650cc in the Dominator, then 750cc in the Atlas and Commando. Norton was keen to have racing success with the twin, to enhance road bike sales – win on Sunday, sell on Monday – but race-tuned Dominators were outclassed by the twin-overhead-camshaft Manx Norton.
Highly developed 500cc Dominator engines produced 55bhp (41kW) and revved to 8000rpm. The factory ‘Domiracer’ bikes were 16kg lighter than the Manxes and in the 1961 Isle of Man TT, Aussie Tom Phillis scored third place and lapped at over 100mph (161 km/h) – a first for a pushrod engine and a first for any twin. However, Norton abandoned the Domiracer project a year later.
The Commando engine retained the 73mm (2.9 in) x 89mm (3.5 in) bore and stroke dimensions of the Atlas engine, but compression was raised to 8.9:1 and the engine breathed through two 30mm Amal Concentric carburettors and the power output increased to 58bhp (43kW) at 6500rpm.
An alternator replaced the previous magneto and dynamo. Points for the coil ignition were mounted on a chain-driven jackshaft at the rear of the engine, where the magneto had previously been positioned. Later engines had the points on the end of the camshaft, being accessible behind a plate on the timing cover and the rocker covers were polished.
The transmission was a pre-unit, four-speed Norton gearbox with a new diaphragm clutch and triplex primary drive.
Early Commando engines had premature main bearing failures, so in late 1971 a stiffer crankcase was introduced and the drive-side main bearing changed from ball to roller, with shim preload adjustment.
The disastrous ‘Combat’ engine was introduced in January 1972, using some parts from the production racing engine. It had a 10:1 compression ratio, an ‘lumpy’ camshaft and 32mm carburettors that made it good for 65bhp (48kW) at 6500 rpm.
However, gearing was changed to improve acceleration and that led to easy over-revving. Also, it was difficult to service and was dropped in 1973, in favour of the 828cc, ‘850’ Commando.
The 750 Commando used Norton’s Isolastic frame, designated GlideRide, with rubber bushes to isolate vibration from the frame and rider. The Featherbed frame was retained for less-powerful models.
Roadholder forks were carried over from the Atlas, as were the mufflers and an eight-inch, twin-leading-shoe front brake.
Head stock failures in the USA dictated frame changes in 1969 and revised centre- and side-stands came in 1970.
A front disc brake was added as an option from early 1972 and became standard in mid-1972.
The original model was designated the ‘Fastback’ in 1969, to differentiate it from the S, Roadster and R models. A metal tank, wider front tyre, upswept exhausts and reverse cone megaphone silencers were fitted on the 1971 Mk3.
Oggy’s Commando 750
Nortons had always impressed Oggy, from his early days, watching Manx-powered go-karts do well in hill climbs and he later got into bikes. His previous Norton bike was a Roadster model.
He always wanted a fastback Commando, so after retiring in 2008, he located one in pretty poor condition and the work started. Three years later, you can see the magnificent result.
The Fastback panel and mudguard were in a bad state, but responded to treatment and the finishing touch to all the body work was a paint job by Eade Brothers, who go a long way back with Nortons, having given many bikes the custom-paint treatment from the 1960s.
Oggy’s bike looks stock, but has some upgrades that don’t distract from its appearance. He said that the Amal carries on his previous Roadster model were trouble free, but the ones on the Commando engine were nothing but trouble. The ‘fix’ is a single Mikuni.
Another useful upgrade is electronic ignition.
Of course, it wouldn’t be vintage Norton without some quirks and Oggy reports that it’s not an ideal machine for start-stop operation:
“It’ll kick start just fine initially and for one or two warm starts after that, but then it becomes quite temperamental,” he said.
Ah, yes, Pommy bikes – don’t we just love ‘em.