Classic Motorcycle Build

Norton Commando Upgrades

For those more interested in rideability than originality, there are many sensible upgrades for classic Norton Commando motorcycles. None of these are permanent changes, and your bike can be returned to original at any time.

Norton Commando motorcycle ad

Dual Carb to Single Carb

Although it's actually a performance downgrade, switching from two carburetors to one will save you a lot of maintenance. A bit of top-end will be lost, but be honest, how often do you run wide-open-throttle?

Norton Commando upgrades

As an offset, start-up, low-end, and midrange power are improved.

single carb Norton Commando

Mikuni Carb Kit

To change from two carbs to one, the intake manifold needs to be replaced, and the air box either replaced or modified. Sudco International offers Mikuni conversion kits in 34, 36 and 38mm sizes.

single Mikuni carburetor for Norton Commando

A 34mm would be for more the main street cruiser, more stop-light to stop-light action, while a 38mm is better suited for more highway-type riding. Best all-around size would be a 36mm.


Hydraulic Clutch

For those who have never ridden an old British Twin, the clutch lever pull is quite hard by today's standards. Adding a hydraulic clutch will give a much easier pull than the stock mechanical style.

hydraulic clutch upgrade for Norton Commando

Offered by Colorado Norton Works, this hydraulic clutch kit is designed to work on all-year Commando transmissions. The slave cylinder is mounted inside the outer transmission cover for an uncluttered look.

Aside from the easier pull, other benefits include more positive clutch engagement and less cable wear and breakage.

NOTE: The CNW hydraulic clutch kit is not always in stock.


Electric Start

Based in Brittany France, Alton offers a range of products for British motorcycles, including generators and electric starter kits. This starter kit for the Norton Commando comes with all you need for assembly, including an installation guide.

No modifications are required, and your bike can be returned to stock condition if so desired. The kick starter stays in place and remains fully functional.

Norton Commando electric start conversion kit

The Alton electric start kit will work with pre-1975 Commandos (except very early models with ignition at the rear of the timing cover). A higher output battery is recommended.

Electric start kit for Norton Commando

Alton electric start kits are available from Classic Bike Experience.


MK3 Isolastics

Later model Commando MkIII models have adjustable isolastics, early models do not. Adjusting and shimming the stock isolastics on early (pre-1974) bikes require a bit of skill and a lot of patience. There are two ways to upgrade.

You can install the later 850 MkIII kit, which will require the front tube to be either shortened or replaced with the MkIII front mounting.

sensible upgrades for Norton Commando

A second alternative is to buy a complete vernier conversion kit, which directly fits pre-MkIII models without any modifications.


Wheel/Tire Sizes and Gearing

All classic Norton Commandos left the factory with 19" wheels. In today's market, there are limited tire choices in 19". Swapping to 18" wheels will allow more tire choices.

Replacing the factory 19-tooth front sprocket to a 21- or 22-tooth sprocket will bring engine revs down at highway speeds without affecting the bike's power band.

Norton Commando gearing

This 19 tooth front sprocket was purchased from British Bike Connection.


There are many other upgrades, big and small, for classic Norton Commandos. Here's a few others:

Front Brake Drum to Disc

No doubt, the twin leading shoe drum brake on early Commandos is impressive looking, but there's a level of skill needed to set it up effectively. Swapping from drum to disc has been a common swap for decades.

twin leading shoe front brake Norton Commando

Due to the caliper mounting, swapping from front drum to disc on a Commando requires different front forks. There are several brands of brake conversion kits readily available.

Other brake upgrades include re-sleeving the original disc master cylinder down to 13mm to get better pressure. Replacing the front rubber brake line with a steel braided line is another popular upgrade.



On older or high mileage vehicles, wear in the distributor usually affects the engine timing, which leads to a falling away of performance. Because electronic ignition has no moving parts, it does not wear, saving maintenance.

Electronic conversion kits are available from several reputable companies, including Boyer Bransden.

Along with electronic ignition, a switch from dual to single coil. Also consider re-wiring the bike to negative ground.


SAE vs Whitworth Hardware

Many British motorcycles, including Norton, continued using Whitworth-sized nuts and bolts into the 1970's. To make things confusing, some models have a combination of SAE (American) and Whitworth nuts and bolts. To compound this problem, a previous owner may have likely changed (or damaged) some of the original hardware while removing them.

If you don't own them already, consider investing in a set of Whitworth tools for your classic British motorcycle.


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