Let us start with a potentially very dangerous and costly item, the big end bolt (Part# 06-6486).
In our picture you find two bolts; the top one is Andover Norton, the bottom one is sold to the trade at the same figure we currently pay for just the forging of each bolt, i.e. before it is hardened, the thread rolled, ground to size etc… By the time our bolt is finished and sold to the dealer, it costs far more than the pirate bolt- hence the motivation for the dealer to sell the pirate part, purchased cheaply and sold with a very hefty profit.
Our bolt is not just dimensionally different to the pirate part below it, as a forging it is far stronger than the pirate bolt that is turned from solid bar. Our threads are rolled, and as every engineer knows, a rolled thread is far more resistant to tensile loads than a cut thread.
If and when the pirate bolt gives up- and we hear this has happened on numerous occasions, the damage is normally devastating and will at best cost a conrod, piston, and valve(s), at worst the crankcase and more.

The pirate bolts are easy to identify by the following points:

Their length- ours are 62.6mm, “pirate” are 63.3 mm long.

At the end of the threaded section on the “pirate” there is a section of uncut thread.

The “pirate” main ground diameter length is 15mm long.

To re-iterate- these “pirate” bolts do not have the tensile strength required for this application and should not be used.

From big end bolts to conrods. 

We are convinced- and our own experience with very reliable racing engines with a lot more power and torque than any standart production engines proves it- that our standard production Genuine Norton Factory Parts conrods (right) will stand all stresses they are likely to encounter in a Commando engine. 

Other offerings are in the market. Steel conrods, heavy and asking for considerable re-balancing iof the crank and therefore the answer to no question, and aluminium conrods machined from billet.

The billet conrods look "nicer" than ours, and look more substantial, too. This they are- in weight, 10grams to be exact- but not in strength. Furthermore, they have a lot more weight near the small end, where one does not want it. Original conrods are far lighter in this crucial area.

Our original conrods are made from forgings. A forging is far stronger than a piece of alumunium that is then machined to shape. As with the big end bolts above, whilst a part turned from billet may LOOK nicer, it is in fact far less equipped to take stresses than a forged part. It can only take the same stresses as a forged part if far more material is being used to make it and it is then substantially bigger and heavier than the forged part.

If no forged conrods were available to rebuild a Norton engine I might be tempted to use the billet one on the left and take it easy on the engine to compensate. However, as our forged rods are available, and have withstood up to 8.500rpm in a friend's racing Commando repeatedly, so are more than up to the job in any given Commando application, I use nothing else for road and race engines.

The rod failures I have seen in the last thirty years always had a basic technical reason- engine ran out of oil, rod was mechanically damaged when installed, wrong con rod bolts or re-used big end nuts and bolts. With an original conrod I have yet to see a failure caused by weakness of the rod itself.

I therefore use Genuine conrods in all my own Commando engines, road and race, and recommend to do as I do.

Not potentially costly, but wasted money nonetheless- Dominator/early Commando headlamp brackets. (Indian “pirate” part on the left)

These beauties (grey/brown primer paint) are Made in India, and it is likely that less scrupulous e-bay vendors sell them as "genuine". At first glance the poor welding of the headlamp holding "ear" is obvious, as is the round hole with the washer welded behind it where the original has an oval to allow for directional adjustment of the headlamp. Less obvious at first glance is the fact that they do not fit! The headlamp bracket should have a portion with a reduced diameter at the bottom that locates the bracket in the upper fork shroud. These Indian brackets cannot be located correctly at best, at worst can't be fitted at all.

Another potential failure- swinging arm mounting parts.

These “pirate” bushes (left) are turned from bronze bar, not sintered as they should be (right) in order to absorb the oil they are lubricated with. The machined bronze stock bar cannot absorb oil and will wear very quickly, resulting in play in the swing arm and erratic roadholding. Apart from the material another giveaway is the internal chamfer which is not concentric with the bore. This chamfer was obviously made by hand rather than as part of the machining process.

We did not go to the length of having the steel of the axle analysed, It is easy enough to recognise in that the centre screw that secures the axle in the subframe is not the correct UNF thread but a metric thread. Another clue is the general poor standard of manufacture, as can be seen on the ends of the axle (genuine axle left resp. top).

All genuine swinging arm spindles have a central thread for the locating screw as well as two cotter pin slots and are also hard chrome-plated.

Another problem area is the gearchange lever, that is sold for AMC gearboxes and stated to be suitable for Commandos. Not only are the pattern levers too long, but the splines are the wrong pitch and not properly formed, as you will notice when you try to push it onto the gear change shaft. The Andover Norton lever (bottom resp. right) can be pushed on by hand, the Indian counterpart needs a hammer. And has a metric M6 pinch bolt through it!

Air Filter Element- 850 Mk1A, Mk2A, Mk3

Another prevalent pirate part is the disintegrating air filter; a difficult one to identify straight away. What happens is that the cheap foam is drawn into the engine, with two big problems resulting from this- the damage caused by the melted foam depositing inside the engine and carburettor, and the lack of any air filtration after a very short time with the associated consequences!

The way to identify these is from the structure of the wire mesh inside. It can be seen in the photograph that our sample pirate filter (left) shed its foam within months lying on a shelf unused , this problem will be accelerated dramatically when the filter is exposed to petrol vapour when in use. Genuine Filters (right) have a wider wire mesh inside which can be felt though the foam.

The "Peashooter" Norton silencer.

Not a critical item one might think, and there are plenty of offerings in the market. However, it is crucial to engine performance to get the proper item. Andover Norton sells four different versions- the seamless one in the picture, one with seams as on the 850s, one with "Norton" logo and seams, and a special one with 1 1/2" (38mm) inlet for specials and Triumphs. All of them are identical internally.

The crucial feature are the internals. They must be absorption dampers-. many cheap ones are labyrinth ones that you can't see through- and, also very important, not only for sound but for performance, it must have "flutes" in the internal through tube, not a tube with holes. Anything but the original style internals will decrease performance, even the production racers had the same internals.

Front mudguards

Not necessarily a safety or performance related item, but one that is the finishing touch to the motorcycle. We have recently seen stainless front mudguards Made in India. The colour of the stainless is different to ours, the radius is slightly off, but a very significant feature is the front lip, which in our case requires a costly press tool that the imitation never had the benefit of, so looks amateurish in comparison.

We have since heard they tend to crack, probably because the hand-formed lip is not as free of local stresses as our pressing, or because the steel of the mudguard is different.

Indian mudguard right, genuine part left.