Douglas 2 3/4hp And Flat Tank Bikes - Original Amac Carb Type - Main Jets: Various Size (Each)

Product no.: 1242 Amac_1645D

In stock

Recommended Retail Price, plus delivery

This listing is for the small main jets, as fitted to many Amac carburettors from the early 1900's until Amac (and two other manufacturers) amalgameted to form Amal, in approximately 1927.  These main jets are meant for needleless carbs - including the Douglas 2 3/4hp type Amac HYD carb shown in the photo - and are available in a variety of sizes.  See listing for further detail. 

This listing is a Variable listing - the drop down will show the jet sizes we have available.  Each jet comes stamped with the original Amac jet size.

Price is each.

These jets are CNC machined by ourselves to the same dimensions as original Amac Jets - and original period Amac jets were used as the patterns (see photographs).

We offer the jets in a variety of the most common jet sizes used on early Douglas 2 3/4hp models (which were shown in the Douglas 2 3/4hp Spare Parts List of 1924 as being part number 1645 with jet sizes varying from 24/32). 

However, we also have a few in larger sizes (limited quantities), likely to have been fitted to later Amac carbs (and other marques) into the mid 1920's - and you can email us if you have a specific requirement - if there is enough demand, we may make small batch's of other sizes in the near future - email me at  You can also email us if you require more information on Amac jet sizes vs later Amal jet sizes.

Note for Douglas 2 3/4hp owners - one of the period Douglas owners guide show the 2 3/4hp model requiring either a 27 Jet or 28 Jet, dependent on if a gauze is used (and which type of Amac carb is fitted).  Due to difficulty in modern times of acquiring the original size Micro Drills - we can offer either a 26 or a 28 jet (as well as other similar sizes), but not the 27 size - However, it should be noted that the difference between these jet sizes are miniscule! (they are all extremely small holes!).

Final point.  These jets are not cheap - this is due to them being made in very small batches - and being extremely difficult to machine with such small drill sizes . . . inevitably requiring a lot of setup and very slow CNC feed rates and high machining speeds (With the cost of drill breakages taken into account! . . . frankly I have no idea how they made them reliably a 100 years ago on manual machines!).  Due to their rarity to find these days, we hope you would prefer them to be offered at all, even if slightly nore expensive than later type main jets made in mass quantities by other companies

Browse these categories as well: 1z. Douglas 2 3/4hp and 1912-25 Douglas/Edwardian Parts, 2.d Parts to fit: Original Amal/Amac Roadgoing Carbs (Type 76/276, 86/286, 289, Monobloc etc), 2.a Parts to fit: Original Amal TT Competition Carburettors