This item is the 15 tooth Norton single magneto chain sprocket on the engine side - that drives the chain to the magneto sprocket, it fits on the end of the oil pump drive gear (SOHC models) or inlet cam (OHV and SV models).
These sprockets are manufactured to to the original Norton profile, and were as used on most Norton single cylinder models (i.e. SOHC, OHV and SV singles) from the 1930's to late 1950's. When manufacturing these sprockets, we used an original Norton 'New Old Stock' sprocket as the pattern.
Price is Each.
We manufacture these sprockets in-house, on modern CNC machinery and to a very high standard. They are then hardened (the slight black, mottled finish is as a result of the hardening process). They are supplied sprayed in Duck Oil (the wet look in the photographs) to prevent rusting in storage.
They should fit most Norton singles from the late 1920's to the late 1950's - including SOHC models, OHV and Side Valve models. The only difference to the original Norton design - is that we do not include a slot for a 'woodruff' key on these sprockets - as it is almost universally accepted that the use of a woodruff key on this sprocket is unnecessary - and actually can be quite harmful, as it is the taper that gives almost all of the grip, and if a woodruff key is used that sits even a fraction too proud of the slot - it will result in a lack of contact of the taper, and therefore more chance of failure). FYI - I have never used a woodruff key on this engine sprocket in 40 years of ownership of all varieties of SOHC,OHV and SV ownership.
We manufacture these sprockets in-house, and do not offer them to any other outlet, they are exclusive to ourselves. We used original Norton sprockets to ensure dimensions were as original, and the spocket tooth profile is the correct CNC generated profile for the imperial Renolds chain that we can also supply for most Norton single models.
Note: Fitting magneto sprockets - it is always best when fitting sprockets, to smear some fine grinding paste on the taper fit of the sprocket and gently grind the sprocket to the taper, to get a perfect fit. This is achieved when you have got a matt grey finish on both sprocket and taper. Ensure you fully remove the grinding paste before final fitting. Always use a 'puller' to remove the sprocket, do not try to lever the sprocket off with a screwdriver, as this will almost certainly damage the timing case. A tip when using puller's to remove sprockets - fit puller and screw central bolt until a good tension is reached, then give the end of the puller bolt a sharp sideways tap with a mallet - the jarring will easily loosen the sprocket
Update March 2024: Now back in stock - we have just had a new batch of these manufactured. See also Item 0392, the matching magneto side sprocket
