Tagged: Isolastic

Oooh, Shiny! 1974 Norton Commando Roadster

1974 Norton Commando R Side Front

Classic British motorcycles like this 1974 Norton Commando seem to have their devoted legions of fans for the same reasons American musclecars do: they’re relatively available, easy to tinker with and modify, and simple to make into a strong statement that reflects the individual owner, for better or for worse. Parts interchange between models and even brands, the basic engineering is solid, or at least straightforward to remedy, and there is huge aftermarket support.

Nortons of the period were a bit like the John Bloor’s resurrected Triumph of the 1990s: modular designs allowed the factory to tailor bikes to fit niche markets, like the Interstate that was clearly intended to speak to American fans. But after the 1973 shift from the 750 to the 850 version, they were all built around the 828cc engine in different states of tune.

1974 Norton Commando L Side Rear

They also featured Norton’s solution for the increasing vibration supplied by their ever-larger parallel twin. Parallel twins are compact and inexpensive to manufacture compared to a v-twin or multi. But while modern models use all sorts of balance-shaft trickery to prevent vision-blurring and hand-numbing vibration, bikes in the 1950s and 1960s relied on tricks like odd rubber footpegs [see: Benelli Tornado] or the sheer cussedness of the rider to combat fatigue.

1974 Norton Commando L Side Engine

Norton’s solution was the perfect example of plucky British workshed engineering: they basically used rubber mounts to isolate the engine, transmission, and swingarm from the rider. Those bits were left to vibrate happily while the rider racked up the miles in relative comfort. For such a simple concept, the Isolastic mounting system works very well but must be carefully maintained, as worn bushings can lead to vague and unpredictable handling.

1974 Norton Commando R Side

This particular machine’s classic looks actually suggest a 1950s machine to me, with all that bare, polished metal. But the builder has clearly spent a great deal of effort and money to update the bike functionally in as many ways as possible.

From the original eBay listing: 1974 Norton Commando for Sale

Custom build using the best parts available. I started with a 1974 frame and installed a 750 hi performance motor that I rebuilt for just such an occasion. Most if not all the parts are new or better than OEM replacements.

This is a partial list:
Engine # 20M3S 132501
New valves, springs, pistons and rings
High performance camshaft
Amal 32mm carbs
Dave Taylor head steady
Venhill braided Stainless rocker feed lines
“Big Bore” 1-1/2″ exhaust system
RGM Belt Drive Primary
Quaife polished gearbox case
Alton Electric start kit
Shorai Battery
Stainless steel transmission adjustment hardware kit
Jim Comstock hydraulic actuated clutch with Brembo Master cylinder
New drive chain with 21tooth countershaft sprocket
New polished Excel rims with stainless steel spokes and nipples
New Bridgestone tires
Hagon Shocks
Performance machine 4 piston caliper with Brembo Master cylinder
Baja Designs light switch / directional switch combo
Solid state charging system
Rebuilt gauges
Custom quartz headlight incorporating LED turn signals
RGM 3.5 gallon custom alloy gas tank
Custom alloy seat and Corbin gunfighter seat
New fork tubes, seals etc
Bucketloads of stainless steel hardware
New wiring harnesses

As you can see from the list, this is a serious amount of money invested in the parts alone. The Alton E-Start kit alone retails for $2495 and drives the crank directly without going through the primary so it spins the engine with very little effort. If you’re looking for something completely different, this is the one. I have ridden the bike to put some shakedown miles on it and everything is working well.

1974 Norton Commando R Side Rear

Oftentimes, it’s the perfectly preserved, completely original bikes that command the hearts and dollars of collectors. But the Commando seems to buck that trend, as long as the updates and modifications are the right updates and modifications… Bidding is currently up to $9,100.00 with the Reserve Not Met and a $14,995.00 Buy It Now option. Nortons were always easy to modify and lent themselves to tinkering, modifying, and improving. A bit like the MGB, you can just about build one from an aftermarket catalog, assuming you have a frame number to start with. This one seems to use the best of the old and the best of the new to create something that captures the classic British biking spirit.

It may not be to everyone’s taste, but it is very classic and the completed bike is very… polished.


1974 Norton Commando L Side

1973 Norton Commando Interstate

1973 Norton Commando Interstate R Front2

My recent “blue” theme continues this week with a very, very clean 1973 Norton Commando Interstate. The different Nortons of this period are largely differentiated by cosmetic and ergonomic details: they all used the same 828cc engine although some models did feature a higher state of tune.

1973 Norton Commando Interstate Engine

As Norton increased the displacement of their classic twin through the Dominator and Atlas models in order to keep pace with their competition, vibration of the parallel-configuration became an issue. Instead of rubber-mounting the controls and blunting feel, or redesigning the engine, which was not economically feasible, they ISO-lated the engine, transmission, and swingarm from the rider with their “Isolastic” mounting system.

ISO-late and e-LASTIC. Get it?

This system of rubber mounts works very well, and the bike displays excellent period handling and very good power, although it’s important to keep the system in good nick and set up properly: too tight and the twin’s characteristic vibration will rear its ugly head. Too loose and handling can deteriorate significantly.

1973 Norton Commando Interstate Clocks

Translated from the original Capital-ese eBay listing: 1973 Norton Interstate 850 for Sale

Wonderful 1973 Norton, 850cc Interstate Motorcycle
I am the original owner of this like show room wonderful piece of motorcycle nostalgia
The bike has 10 thousand miles, has been garage kept, is a wonderful royal blue color
Runs excellent- ready to ride

The listing may be pretty vague, aside from letting us know that this wonderful motorcycle is wonderful, but the pictures speak volumes. A couple are pretty dark, but the do show off the seller’s garage which, although slightly cluttered [Peek-a-boo, C4 Corvette!] looks to have a spotless floor. Which, as a Norton owner means he replaces the various gaskets weekly, has a full time cleaner for the floor, or the bike has never been started.


The bike is spotless as well and looks like it may have actually been licked clean prior to the photographs being taken…

1973 Norton Commando Interstate R Rear

But an original-owner bike, with 10k miles? It’s no surprise that the reserve hasn’t been met yet at $5,600. There’s three days left on this auction, and this bike surely deserves to fetch more than that.


1973 Norton Commando Interstate L Front