Oct 18th 2018
Amal Concentric Carburetor Tuning & Jetting Guide | JRC Engineering
1. How the Carburetter Works
The carburetter proportions and atomises the right amount of petrol with the air drawn in by the engine, owing to the correct proportions of the jet sizes and the main choke bore. The float chamber maintains a constant level of fuel at the jets and cuts off the supply when the engine stops.
The throttle control from the handlebar controls the volume of mixture and therefore the power, and at all positions of throttle the mixture is automatically correct. The opening of the throttle brings first into action the mixture supply from the pilot jet system of idling, then as it progressively opens via the pilot by-pass, the mixture is augmented from the main jet, the earlier stages of which action is controlled by the needle in the needle jet. The pilot jet system is supplied by the pilot jet (30) which is detachable on removal of the float chamber. On certain other models no pilot jet is fitted but a pilot bush is inserted in the continuation of the pilot air adjusting screw passage. The main jet does not spray directly into the mixture chamber, but discharges through the needle jet into the primary air chamber, and goes from there as a rich petrol-air mixture through the primary air choke into the main air choke.
The carburetters usually have a separately operated mixture control called an air valve, for use when starting from cold, and until the engine is warm; this control partially blocks the passage of air through the main choke.
This design of carburetter offers perfectly simple and effective tuning facilities.
Note on pilot jet variants: The far right drawing above shows a vertically oriented threaded pilot jet (#30). This configuration is only found on 1968 Concentrics. The Concentric bodies retain the vertical threads for two-stroke applications, but all four-stroke carbs were supplied with a pressed-in bush — see the centre diagram. Premier versions of the MK1 Concentric have replaced the pressed-in bushing with a threaded brass/steel jet opposite #34 (pilot air adjusting screw).
Parts Reference — Amal Concentric Components
| 1. Mixing Chamber Top | 2. Air Valve Spring |
| 3. Air Valve Spring | 4. Air Valve |
| 5. Float Needle | 6. Needle Seating |
| 7. Filter Gauze | 8. Banjo |
| 9. Banjo Bolt | 10. Cable Adjuster (Air) |
| 11. Cable Adjuster (Throttle) | 12. Cable Adjuster Locknuts |
| 13. Carburetter Body | 14. Throttle Valve Spring |
| 15. Jet Needle Clip | 16. Pilot By-pass |
| 17. Pilot Outlet | 18. Float Chamber Body |
| 19. Float | 20. Mixing Chamber Top Screws |
| 21. Throttle Valve | 22. Jet Needle |
| 23. Choke Tube | 24. Needle Jet |
| 25. Tickler | 26. Throttle Adjusting Screw |
| 27. Float Chamber Washer | 28. Jet Holder |
| 29. Main Jet | 30. Pilot Jet |
| 31. Pilot Jet Feed Passage | 32. Feed Passage From Pilot Jet |
| 33. Pilot Air Feed Passage | 34. Pilot Air Adjusting Screw |
2. Hints and Tips
Starting, from cold: Turn on fuel supply, set ignition (if manually operated) for best slow running, depress tickler to flood float chamber, close air valve, open throttle slightly and start engine. When engine starts open air valve and close the throttle; if engine begins to falter, partially close the air valve until engine is warm, then set in fully open position.
Starting, engine hot: Open throttle slightly and start engine. It should not normally be necessary to flood the float chamber or close air valve when starting a warm engine.
Starting, general: Experience will show when it is necessary to flood the carburetter or use the air valve, and also the best setting of the throttle valve. If the carburetter has been over-flooded or strangled — which would result in a wet engine and over-rich starting mixture — fully open the throttle valve and air valve, give the engine several turns to clear the richness, then start again with air valve fully open and the throttle valve slightly open.
Starting, single lever carburetter: Open the throttle very slightly from the idling position and flood the carburetter more or less according to the engine being cold or hot respectively.
Cable control: See that there is a minimum of backlash when the controls are set back and that any movement of the handlebars does not cause the throttle to open; this is done by the adjusters on top of the carburetter, after releasing the adjuster locknuts. See that the throttle valve shuts down freely, then reset locknuts.
Petrol feed: A filter gauze is fitted at the inlet to the float chamber. To remove this gauze, unscrew the banjo bolt (9) — the banjo and filter gauze can then be removed. Before replacement ensure that the filter gauze is both clean and undamaged and check fuel supply by momentarily turning fuel tap. Vertical loops in petrol pipes must be avoided to prevent air locks. Float chamber flooding may be due to worn float needle, but nearly all flooding and blockage of the filter gauze on new machines is due to impurities from the tank. Periodically clean out filter gauze and float chamber until trouble ceases, or alternatively the tank may be drained and swilled out.
Fixing the carburetter and air leaks: Erratic slow running is often caused by air leaks, so verify there are none at the point of attachment to the cylinder or inlet pipe. A sealing ring is fitted into the attachment flange of the carburetter. On old machines, also look out for air leaks caused by a worn throttle valve or worn inlet guide.
Banging in exhaust: May be caused by too weak a pilot mixture when the throttle is closed or nearly closed — also by too rich a mixture and air leaks in the exhaust system. In either case the reason is that the mixture has not fired in the cylinder and has fired in the hot silencer. If the banging happens when the throttle is fairly wide open the trouble will be ignition, not carburation.
Bad petrol consumption: On a new machine, may be due to flooding caused by impurities from the petrol tank lodging on the float needle seat, preventing its valve from closing. Flooding may also be caused by a worn float needle valve. Bad petrol consumption will also result if the needle jet (24) has worn; this may be remedied by lowering the needle in the throttle, but if improvement is not possible, the only remedy is to fit a new needle jet.
Air filters: These may affect the jet setting, so if one is fitted afterwards the main jet may need to be smaller. If the carburetter is set with an air filter and the engine is run without it, take care to avoid overheating due to a weak mixture; testing with the air valve will indicate that a larger main jet and higher needle position are required.
Effects of altitude on carburetter: Increased altitude tends to produce a rich mixture. The greater the altitude, the smaller main jet required. Carburetters ex-works are set suitable for altitudes up to approximately 3,000 feet. Carburetters used constantly at 3,000–6,000 feet should have a reduction in main jet size of 5%. For every 3,000 feet in excess of 6,000 feet, make further reductions of 4%.
3. Re-assembling
When replacing the valve assembly, see that the jet needle goes into the holes in the choke tube, needle jet and main jet, and that both the throttle and air valve spring locate correctly in the mixing chamber top.
When refitting the float, engage the float needle recess in the horseshoe section of the float and fit in the float chamber. Check that the needle jet (24), jet holder (28) and main jet (29) are fully tightened together before screwing the assembly into the body.
How to Trace Faults
There are only two possible faults in carburation: either richness or weakness of mixture.
| Indications of Richness | Indications of Weakness |
| Black smoke in exhaust | Spitting back in carburetter |
| Petrol spraying out of carburetter | Overheating |
| Four-stroke, eight-stroking | Acceleration poor |
| Two-stroke, four-stroking | Engine goes better when throttle is not wide open or air valve is partially closed |
| Heavy, lumpy running | |
| Spark plug sooty |
If richness or weakness is present, check if caused by:
- Petrol feed — check that jets and passages are clear, that the filter gauze in the float chamber banjo is not choked with foreign matter, and that there is ample flow of fuel. Check there is no flooding.
- Air leaks — at the connection to the engine or due to leaky inlet valve stems.
- Defective or worn parts — such as a loose-fitting throttle valve, worn needle jets, or loose jets.
- Air cleaner choked up.
- Air cleaner having been removed.
Removing the silencer or running with a straight-through pipe requires a richer setting.
Having verified the correctness of fuel feed and that there are no air leaks, check over ignition, valve operation and timing. Then, at throttle position 4 (see Fig. 5), test to see if the mixture is rich or weak by partially closing the air valve. If the engine runs better, weakness is indicated; if worse, richness is indicated.
| To Cure Richness | To Cure Weakness |
| 1. Fit smaller main jet | 1. Fit larger main jet |
| 2. Screw out pilot air adjusting screw | 2. Screw pilot air adjusting screw in |
| 3. Fit a throttle with larger cutaway | 3. Fit a throttle with smaller cutaway |
| 4. Lower needle one or two grooves | 4. Raise needle one or two grooves |
Note: Do not try to cure a rich mixture at half throttle by fitting a smaller main jet, as the main jet may be correct for full power at full throttle. The proper remedy is to lower the needle.
4. Parts to Tune Up
Throttle adjusting screw (26): Set this screw to hold the throttle open sufficiently to keep the engine running when the twist grip is off. An “O” ring is fitted to the screw to hold this adjustment by friction.
Main jet (29): The main jet controls the petrol supply when the throttle is more than three-quarters open, but at smaller throttle openings, although the supply of fuel goes through the main jet, the amount is diminished by the metering effect of the needle in the needle jet. Each jet is calibrated and numbered so that its exact discharge is known and two jets of the same number are alike.
Never ream a jet out — get another of the right size!
The bigger the number, the bigger the jet. To remove the main jet, remove the float chamber; the main jet can then be unscrewed from the jet holder (28).
Needle and needle jet (22 and 24): The needle being tapered either allows more or less petrol to pass through the needle jet as the throttle is opened or closed throughout the range, except when idling or at nearly full throttle. The needle position relative to the throttle valve can be set by repositioning the jet needle clip in any of three grooves, thus raising or lowering it. Raising the needle richens the mixture and lowering it weakens the mixture at throttle openings from quarter to three-quarters open. Throttle needles are marked with a single groove around the top diameter for the 600 series carburetter; 900 series carburetter needles are identified by three grooves; needles marked with two grooves are used on certain models for both 600 and 900 series carburetters.
Throttle valve cut-away: The atmospheric side of the throttle is cut away to influence the depression on the main fuel supply and gives a means of tuning between the pilot and needle jet range of throttle opening. The amount of cut-away is recorded by a number marked on the throttle valve (e.g. 622/3 means throttle valve type 622 with a No. 3 cut-away). Larger cut-aways (4 and 5) give weaker mixtures; a No. 2 gives a richer mixture.
Air valve (3): Used only for starting and running when cold. Otherwise run it wide open.
Tickler (25): A small plunger, spring loaded, fixed in the carburetter body. When pressed down on the float the needle valve is allowed to open and so “flooding” is achieved. Flooding temporarily enriches the mixture until the petrol level subsides to normal.
Alcohol fuels: When using alcohol fuels, the following components are necessary: a metallic banjo (preferably double feed if not already fitted), float chamber 622/051, banjo bolt washer 13/163, needle jet 622/100, jet needle 622/099 or 928/099 according to type, filter gauze 376/093B and banjo washer 14/175. The main jet must be increased for straight alcohol by approximately 150%. The final setting must be determined by trial and error according to the nature of the fuel being used. When using alcohol fuels, err on the rich side to avoid engine overheating.
5. How to Tune Up
Fig. 5 — Phases of Amal Needle Jet Carburetter: Throttle Openings
Note: The carburetter is automatic throughout the throttle range. The air valve should always be wide open except when used for starting or until the engine has warmed up. Normal petrols are assumed.
Read sections 3 and 4 for each tuning device, and get the motor going on a quiet road with a slight up-gradient so that on test the engine is pulling.
Tune up in the following order:
1st — Main jet (throttle position 1, Fig. 5). If at full throttle the engine runs “heavily,” the main jet is too large. If at full throttle, by slightly closing the throttle or air valve the engine seems to have better power, the main jet is too small. With a correct-sized main jet the engine at full throttle should run evenly and regularly with maximum power. For speed work, ensure the main jet is large enough to keep the engine cool, and verify this by examining the spark plug after taking a run, declutching and stopping the engine quickly. If the plug body at its end has a cool appearance the mixture is correct; if sooty, the mixture is rich; if there are signs of intense heat, the mixture is too weak and a larger main jet is necessary.
2nd — Pilot jet (throttle positions 2 and 5, Fig. 5). With engine idling, twist grip shut, throttle resting on the adjusting screw, and ignition set for best slow running: (1) Screw out the throttle adjusting screw until the engine runs slower and begins to falter, then screw the pilot air adjusting screw in or out to make the engine run regularly and faster. (2) Now gently lower the throttle adjusting screw until the engine runs slower and just begins to falter; adjust the pilot air screw to get best slow running. If this second adjustment makes the engine run too fast, go over the job again a third time. Both the throttle adjusting screw and pilot air screw have an “O” ring fitted to hold adjustment by friction.
3rd — Throttle cut-away (throttle position 4, Fig. 5). If, as you take off from idling position, there is objectionable spitting from the carburetter, slightly richen the pilot mixture by screwing in the air screw sufficiently; if this is not effective, screw it back again and fit a throttle with a smaller cut-away. If the engine jerks under load at this position and there is no spitting, either the jet needle is much too high, or a larger throttle cut-away is required to cure richness.
4th — Needle (throttle position 4, Fig. 5). The needle controls a wide range of throttle opening and also the acceleration. Try the needle in the lower position, with the clip in the groove at the top; if acceleration is poor and with air valve partially closed the results are better, raise the needle by two grooves; if much better, try lowering the needle by one groove and leave it where it is best. If the mixture is still too rich with the clip in groove No. 1 (nearest the top), the needle jet may need replacement due to wear. If the needle itself has had several years of use, replace it also.
5th — Finally: Go over the idling again for final touches.
Tuning Twin Engines with Twin Carburetters (One Carburetter per Cylinder)
First, slacken the throttle stop screws and put the twist grip into the shut-off position to allow the throttles to close; there should be a slight backlash in the cables, obtainable if necessary by screwing in the cable adjusting screws on top of the carburetter after releasing lock nuts. Then, with the handlebars in the normal position and throttles closed, adjust the cable adjusting screws so that on the slightest opening of the twist grip both throttles open simultaneously, then reset the lock nuts.
To set the carburetters, follow the procedure in section 5, bearing in mind these hints: main jet sizes are selected by checking the effect of the mixture on the spark plugs after a run at full throttle; the smallest pair of jets that give the best maximum speed are usually correct provided the plugs show no signs of excessive heat. For critical tuning, one carburetter may require a different jet size from the other.
For slow running, set the twist grip to make the engine run slowly but just faster than a tick-over; gently screw in the throttle stops to hold the throttles in that position and return the twist grip to the shut position, leaving the engine running on the throttle stops.
Then set each carburetter according to section 5 paragraph 2 to obtain the idling by screwing down the throttle stop screws and adjusting the pilot air screws accordingly.
A practical method for setting the pilot is to detach one spark plug lead and set the pilot air adjusting screw on the firing cylinder as a single unit, then repeat for the other cylinder. When both leads are reconnected, the engine may run slightly faster than desired, in which case a slight readjustment of the throttle stop screws will correct this. It is essential that the idling speed on both cylinders is approximately the same, as this directly affects the smoothness of the get-away on initial throttle opening.
It is essential with twin carburetters that the throttle slides are a good fit in the bodies, and that there are no air leaks at either flange attachment to the cylinder.
Regarding the lower end of the throttle range — always the more difficult to set — ensure that the control cables are perfectly adjusted without any excessive or unequal backlash between carburetters; otherwise one throttle will be out of phase with the other, resulting in lumpy running.
To check that both throttles open simultaneously, shut the twist grip so the throttles rest on their stop screws in the final position of adjustment; then insert a finger into each air intake to press on the throttles and, with the other hand, gently open the twist grip and feel that both throttles lift off the stops at the same time.
Triumph & BSA Amal Concentric Jetting Reference
The following factory jetting specifications cover Triumph and BSA models from 100cc to 750cc. Use these as your baseline and adjust as needed for altitude, exhaust modifications, or air filter changes (see section 4).
Shop Amal Concentric carburettors and jets at JRC Engineering →
Triumph Singles and Twins — 100cc to 350cc
| Triumph Singles and Twins 100cc–350cc | |||||||||
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| 100cc | |||||||||
| Tina Scooter | 1961–62 | 32/2 | 23/32″ | 32/023-105 | 4/042-25 | 32/031-105 | 3 | 32/0462 | Included |
| Tina Scooter | 1962–64 | 32/15 | 23/32″ | 32/023-105 | 4/042-25 | 32/031-105 | 3 | 32/0462 | Included |
| T10 Scooter | 1965–66 | 32/18 | 23/32″ | 32/023-95 | 4/042-15 | 32/031-105 | 2 | 32/0224 | Included |
| 150cc | |||||||||
| Terrier | 1953 | 332/1 | 3/4″ | 4/042-120 | 332/016 | 332/002-086 | 2 | 332/00544 | 3EB |
| Terrier | 1954–56 | 332/2 | 11/16″ | 4/042-90 | 376/076-20 | 332/002-086 | 3 | 332/00544 | 3EB |
| Terrier | 1958 | 3332/6 | 11/16″ | 4/042-90 | 376/076-20 | 332/002-086 | 3 | 332/00544 | 3EB |
| T.S.I. Tigress Scooter | 1960 | 363/9 | 13/16″ | 363/044-130 | 376/076-15 | 363/018-106 | 5 | 363/09235 | — |
| 200cc | |||||||||
| T.S.I. Tigress Scooter | 1961 | 363/11 | 13/16″ | 363/044-130 | 376/076-15 | 363/018-106 | 5 | 363/09235 | — |
| T20 Tiger Cub | 1954 | 332/3 | 3/4″ | 4/042-100 | 376/076-20 | 332/002-086 | 3 | 332/00544 | 3EB |
| T20 Tiger Cub | 1955–57 | 332/3 | 3/4″ | 4/042-100 | 376/076-20 | 332/002-086 | 3 | 332/00544 | 3EB |
| T20 Tiger Cub | 1957 | 332/3 | 3/4″ | 4/042-100 | 376/076-20 | 332/002-086 | 3 | 332/00544 | 3EB |
| T20J Tiger Cub | 1957–58 | 332/3 | 3/4″ | 4/042-100 | 376/076-20 | 332/002-086 | 3 | 332/00544 | 3EB |
| T20 Tiger Cub (Export) | 1959 | 332/7 | 13/16″ | 4/042-140 | 376/076-15 | 332/002-86 | 3 | 332/00544 | 3EB |
| T20S Tiger Cub Scrambler | 1959–60 | 376/217 | 15/16″ | 376/100-140 | 376/076-20 | 376/072-106 | 3 | 376/060-3 | 14/620 (remote) |
| T20T Trials, T20 Tiger Cub | 1960–61 | 3765/44 | 25/32″ | 376/100-100 | 376/076-25 | 376/072-105 | 3 | 375/060-3.5 | — |
| T20S & T20SL Scrambler | 1961–67 | 376/272 | 15/16″ | 376/100-1540 | 376/076-20 | 376/072-106 | 3 | 376/060-2.5 | — |
| T20 Tiger Cub | 1962–66 | 32/1 | 11/16″ | 32/023-85 | 4/042-15 | 32/033-104 | 2 | 32/0462 | Included |
| T20 SM Sports | 1965–67 | 376/314 | 15/16″ | 376/100-140 | 376/076-15 | 376/072-105 | 3 | 376/060-3.5 | — |
| T20 Tiger Cub (Export) | 1962–65 | 32/3 | 11/16″ | 32/023-110 | 4/042-15 | 32/033-103 | 2 | 32/0462 | Included |
| T20SS, SH, Scrambler | 1962–66 | 376/272 | 15/16″ | 376/100-140 | 376/076-20 | 376/072-106 | 3 | 376/060-2.5 | — |
| T20 Trials and WD | 1963–66 | 375/44 | 25/32″ | 376/100-100 | 376/076-20 | 376/072-105 | 3 | 375/060-3.5 | — |
| T20B Bantam Cub | 1966 | 375/61 | 25/32″ | 376/100-90 | 376/076-25 | 376/072-105T | 3 | 375/060-3.5 | — |
| T20 Super Cub | 1967 | 375/61 | 25/32″ | 376/100-90 | 376/076-25 | 376/072-105T | 3 | 375/060-3.5 | — |
| T20 French Army | 1973 | R622/10 | 22mm | 376/100-120 | Bush | 622/079-105 | 2 | 622/060-3.5 | — |
| T20B Bantam Cub | 1969 | R622/3 | 22mm | 376/100-120 | Bush | 622/079-105 | 2 | 622/060-3 | — |
| T20B Bantam Cub | 1970 | R622/5 | 22mm | 376/100-120 | Bush | 622/079-105 | 2 | 622/060-3 | — |
| 250cc | |||||||||
| TR25W Trophy | 1969–70 | R928/20 | 28mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| TR25SS Trailblazer | 1971–72 | R928/20 | 28mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| 350cc | |||||||||
| 3HW (Ex W.D.) | 1940–45 | 276AD/1J | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-4 | 1J (15) |
| Tiger “85” | 1946–49 | 275AD/1A | 7/8″ | 4/042-120 | — | 4/061-107 | 3 | 5/052-4 | 1A |
| 3T De-Luxe | 1946–48 | 275AD/1A | 7/8″ | 4/042-120 | — | 4/061-107 | 3 | 5/052-4 | 1A |
| 3T De-Luxe | 1949–50 | 275AQ/1A | 7/8″ | 4/042-120 | — | 4/061-107 | 3 | 5/052-4 | 1A |
| 3T De-Luxe | 1951–52 | 275BK/1A | 7/8″ | 4/042-120 | — | 4/061-107 | 3 | 5/052-4 | 1A |
| 3T (A.A.) | 1953 | 274AB/1AT | 21/32″ | 4/042-75 | — | 4/061-106 | 1 | 4/052-4 | 1AT (7) |
| T21 Twin | 1957 | 375/23 | 13/16″ | 376/100-110 | 376/076-25 | 376/072-105 | 3 | 375/060-3.5 | — |
| T21 Twin | 1957–61 | 375/62 | 25/32″ | 376/100-100 | 376/076-25 | 376/072-105 | 3 | 375/060-3.5 | — |
| T90 | 1963–67 | 376/300 | 15/16″ | 376/100-180 | 376/076-20 | 376/072-106 | 3 | 376/060-3 | — |
| T90 | 1968 | R626/2 | 24mm | 376/100-140 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| P30 Bandit (RH) | 1971 | R626/56 | 26mm | 376/100-140 | Bush | 622/122-106 | 1 | 622/060-3 | — |
| P30 Bandit (LH) | 1971 | L626/56 | 26mm | 376/100-140 | Bush | 622/122-106 | 1 | 622/060-3 | — |
Triumph 500 Twins
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| 5T Speed Twin | 1946–48 | 276AX/1AT | 15/16″ | 4/042-140 | — | 4/061-107 | 3 | 6/052-3.5 | 1AT (7) |
| 5T Speed Twin | 1946–48 | 276DK/1AT | 15/16″ | 4/042-140 | — | 4/061-107 | 3 | 6/052-3.5 | 1AT (7) |
| 5T Speed Twin | 1951–54 | 276FE/1AT | 15/16″ | 4/042-140 | — | 4/061-107 | 3 | 6/052-3.5 | 1AT (7) |
| 5T Speed Twin | 1955–58 | 376/25 | 15/16″ | 376/100-200 | 376/076-30 | 376/072-106 | 4 | 376/060-3.5 | — |
| 5TA | 1958–65 | 375/35 | 7/8″ | 376/100-160 | 376/076-25 | 376/072-105 | 3 | 375/060-3.5 | — |
| Tiger “100” | 1946–48 | 276BN/1AT | 1″ | 4/042-160 | — | 4/061-107 | 3 | 6/052-3.5 | 1AT (7) |
| Tiger “100” | 1949–50 | 276DL/1AT | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-3.5 | 1AT (7) |
| Tiger “100” | 1951–53 | 276FH/1AT | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-3.5 | 1AT (7) |
| Tiger “100” | 1954 | 276GE/2EK | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-3.5 | 2EK |
| T100 Racing (RH) | 1949–50 | 76AH | 1″ | 4/042-150 | — | 4/061-107 | 3 | 6/052-4 | 14/538 |
| T100 Racing (LH) | 1949–50 | 76AJ | 1″ | 4/042-150 | — | 4/061-107 | 3 | 6/052-4 | 14/538 |
| Tiger 100R Race Kit (RH) | 1951–52 | 76AO | 1″ | 4/042-190 | — | 4/061-109 | 3 | 6/052-4 | 14/538 |
| Tiger 100R Race Kit (LH) | 1951–52 | 76AN | 1″ | 4/042-190 | — | 4/061-109 | 3 | 6/052-4 | 14/538 |
| T100C (RH) | 1953 | 76AS | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-4 | 14/538 |
| T100C (LH) | 1953 | 76AR | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-4 | 14/538 |
| Tiger 100C for Daytona / Tiger 100RS | 1955–57 | T15GP | 1″ | 376/100-250 | — | 316/065-107 | 1 | 316/104-6 | 302/11 |
| TR5 Trophy | 1950 | 276EK/1A | 15/16″ | 4/042-140 | — | 4/061-107 | 2 | 6/052-3.5 | 1A |
| TR5 Trophy | 1951–53 | 276FF/1AT | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-3.5 | 1AT (7) |
| TR5 | 1954 | 276GH | 1″ | 4/042-150 | — | 4/061-107 | 2 | 6/052-3.5 | 302/13 |
| Tiger 100, TR5, Trophy & Trials TR5 | 1955–61 | 376/35 | 15/16″ | 376/100-220 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| Tiger 100 (Export, Delta Head pair) | 1957–60 | 376/77 | 1″ | 376/100-200 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| Tiger 100 Twin T100RR (RH) | 1957–59 | T15GP | 1″ | 376/100-250 | — | 316/065-107 | 2 | 316/1046 | 302/19 |
| Tiger 100 Twin T100RR (LH) | 1957–59 | T15GP | 1″ | 376/100-250 | — | 316/065-107 | 2 | 316/1046 | (Remote) |
| TR5A/R/C Competition Twin | 1961 | 376/273 | 1″ | 376/100-190 | 376/076-25 | 376/18-106 | 3 | 376/060-3.5 | — |
| T100SS, T100S, T100R, T100C, T100CR | 1961–67 | 376/273 | 1″ | 376/100-190 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| Tiger T100S T100C | 1968–69 | R626/8 | 26mm | 376/100-180 | Bush | 622/122-106 | 2 | 622/060-4 | — |
| T100, T100C | 1970 | R626/25 | 26mm | 376/100-170 | Bush | 622/122-106 | 2 | 622/060-4 | — |
| T100, T100C | 1971 | R626/32 | 26mm | 376/100-170 | Bush | 622/122-106 | 2 | 622/060-4 | — |
| T100 | 1972 | R626/52 | 26mm | 376/100-170 | Bush | 622/122-106 | 2 | 622/060-4 | — |
| T100T, T100R Daytona (RH) | 1967 | 376/324 | 1 1/16″ | 376/100-200 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| T100T, T100R Daytona (LH) | 1967 | 376/325 | 1 1/16″ | 376/100-200 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| T100T, T100R Daytona (RH) | 1968–69 | R626/10 | 26mm | 376/100-160 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| T100T, T100R Daytona (LH) | 1968–69 | L626/9 | 26mm | 376/100-160 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| T100T Daytona (RH) | 1970 | R626/26 | 26mm | 376/100-150 | Bush | 622/122-106 | 1 | 622/060-3 | — |
| T100T Daytona (LH) | 1970 | L626/27 | 26mm | 376/100-150 | Bush | 622/122-106 | 1 | 622/060-3 | — |
| T100T, T100R Daytona pair (RH) | 1971–72 | R626/53 | 26mm | 376/100-150 | Bush | 622/122-106 | 1 | 622/060-3 | — |
| T100T, T100R Daytona pair (LH) | 1971–72 | L626/54 | 26mm | 376/100-150 | Bush | 622/122-106 | 1 | 622/060-3 | — |
| T100SS Daytona pair (RH) | 1973–74 | R626/64 | 26mm | 376/100-150 | Bush | 622/122-106 | 1 | 622/060-3.5 | — |
| T100SS Daytona pair (LH) | 1973–74 | L626/65 | 26mm | 376/100-150 | Bush | 622/122-106 | 1 | 622/060-3.5 | — |
| TR5T Trophy Trail, Adventurer | 1973 | R928/21 | 28mm | 376/100-180 | Bush | 622/122-1060 | 2 | 928/060-3 | — |
| TR5T Trophy Trail, Adventurer | 1974 | R928/21 | 28mm | 376/100-210 | Bush | 622/122-1060 | 2 | 928/060-3 | — |
Triumph 650 Twins
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| 6T Thunderbird | 1950 | 276EA/1AT | 1″ | 4/042-170 | — | 4/061-107 | 2 | 6/052-3.5 | 1AT (7) |
| 6T Thunderbird | 1951–53 | 276EW/1AT | 1 1/16″ | 4/042-140 | — | 4/061-107 | 2 | 6/052-3.5 | 1AT (7) |
| TR6 & 6T Thunderbird (Export) | 1955–58 | 376/42 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| 6T Thunderbird (Home) | 1959 | 376/42 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| 6T Thunderbird (Export) | 1959–60 | 376/245 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| 6T Thunderbird (Home) | 1959–60 | 376/246 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| 6T Thunderbird | 1960–61 | 376/260 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| 6T Thunderbird (Export) | 1960–61 | 376/256 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| 6T Thunderbird | 1962 | 376/285 | 1 1/16″ | 376/100-220 | 376/076-25 | 376/072-106 | 4 | 376/060-4 | — |
| 6T Thunderbird | 1963–66 | 376/303 | 1 1/16″ | 376/100-220 | 376/076-25 | 376/072-106 | 4 | 376/060-4 | — |
| 6T Thunderbird (USA) | 1964–65 | 376/309 | 1 1/16″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 376/060-4 | — |
| Tiger 110 | 1954 | 289X | 1 1/8″ | 4/042-200 | — | 29/076-107 | 3 | 29/0624 | 302/13 |
| Tiger 110, TR6A, B, C | 1955–61 | 376/40 | 1 1/16″ | 376/100-250 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| Tiger 110 | 1960 | 376/244 | 1 1/16″ | 376/100-250 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| Tiger 110 | 1960–61 | 376/255 | 1 1/16″ | 376/100-250 | 376/076-25 | 376/072-106 | 4 | 376/060-3.5 | — |
| TR6 S/S | 1962–63 | 376/40 | 1 1/16″ | 376/100-250 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| TR6 (inc. Police) | 1964–66 | 389/97 | 1 1/8″ | 376/100-310 | 376/076-25 | 376/072-106T | 1 | 389/060-3.5 | — |
| Metropolitan Police MK III | 1964–66 | 389/97 | 1 1/8″ | 376/100-310 | 376/076-25 | 376/072-106T | 2 | 389/060-3.5 | — |
| TR6 Trophy | 1967 | 389/239 | 1 3/16″ | 376/100-330 | 376/076-25 | 376/072-106T | 2 | 389/060-4 | — |
| TR6, TR6R, TR6C | 1968–70 | R930/23 | 30mm | 376/100-230 | Bush | 622/122-106 | 2 | 928/060-3.5 | — |
| TR6, TR6R, TR6C | 1970 | R930/45 | 30mm | 376/100-230 | Bush | 622/122-106 | 2 | 928/060-3.5 | — |
| TR6 Police | 1970 | R930/65 | 30mm | 376/100-210 | Bush | 622/122-106 | 2 | 928/060-3.5 | — |
| TR6R, TR6C | 1971–72 | R930/60 | 30mm | 376/100-230 | Bush | 622/122-106 | 2 | 928/060-3.5 | — |
| TR6RV, TR6C | 1973–74 | R930/86 | 30mm | 376/100-230 | Bush | 622/122-106 | 2 | 928/060-3.5 | — |
| Bonneville T120 (pair) | 1959 | 376/204 | 1 1/16″ | 376/100-250 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | 14/617 |
| Bonneville T120 (pair) | 1959 | 376/233 | 1 1/16″ | 376/100-250 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | — |
| T120, TR7A (USA), TR7B (Scrambler USA) | 1960 | 389/51 | 1 3/16″ | 376/100-310 | 376/076-30 | 376/072-106 | 3 | 389/060-3 | — |
| Bonneville T120, T120C (pair) | 1960–63 | 376/257 | 1 1/16″ | 376/100-240 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | — |
| T120C, T120RS, T120 T.T. | 1963–67 | 389/95 | 1 3/16″ | 376/100-330 | 376/076-25 | 376/072-106 | 2 | 389/060-4 | — |
| T120R (U.S.A.) | 1966 | 389/203 | 1 1/8″ | 376/100-260 | 376/076-20 | 376/072-106 | 3 | 389/060-3 | — |
| T120 (pair) | 1964–67 | 389/203 | 1 1/8″ | 376/100-260 | 376/076-20 | 376/072-106 | 3 | 389/060-3 | — |
| T120R Johnson Motors | 1963 | 376/302 | 1 1/16″ | 376/100-240 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | — |
| T120, T120R (RH) | 1967–69 | R930/9 | 30mm | 376/100-190 | Bush | 622/122-106 | 2 | 928/060-3 | — |
| T120, T120R (LH) | 1967–69 | L930/10 | 30mm | 376/100-190 | Bush | 622/122-106 | 2 | 928/060-3 | — |
| T120 (RH) | 1970 | R930/43 | 30mm | 376/100-190 | Bush | 622/122-106 | 2 | 928/060-3 | — |
| T120 (LH) | 1970 | L930/44 | 30mm | 376/100-190 | Bush | 622/122-106 | 2 | 928/060-3 | — |
| T120, T120R (RH) | 1971–72 | R930/66 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T120, T120R (LH) | 1971–72 | L930/67 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T120R, T120V (RH) | 1973–74 | R930/84 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T120R, T120V (LH) | 1973–74 | L930/85 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
Triumph 750 Twins
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| T140V (RH) | 1973 | R930/87 | 30mm | 376/100-190 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T140V (LH) | 1973 | L930/88 | 30mm | 376/100-190 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T140V (RH) | 1974–78 | R930/92 | 30mm | 376/100-190 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T140V (LH) | 1974–78 | L930/93 | 30mm | 376/100-190 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| T140D, T140E (RH) | 1979–83 | R2930/2 | 30mm | 376/100-200 | 124/026-25 | 2928/031-105 | 2 | 2928/060-3 | — |
| T140D, T140E (LH) | 1979–83 | L2930/1 | 30mm | 376/100-200 | 124/026-25 | 2928/031-105 | 2 | 2928/060-3 | — |
| T140D, T140E (RH) | 1981–83 | R2930/8 | 30mm | 376/100-200 | 124/026-20 | 2928/031-105 | 2 | 2928/060-3 | — |
| T140D, T140E (LH) | 1981–83 | L2930/9 | 30mm | 376/100-200 | 124/026-20 | 2928/031-105 | 2 | 2928/060-3 | — |
| Harris Bonneville (RH) | 1985–87 | R930/111 | 30mm | 376/100-200 | 124/026-20 | 622/122-106 | 2 | 928/1053 | — |
| Harris Bonneville (LH) | 1985–87 | L930/112 | 30mm | 376/100-200 | 124/026-20 | 622/122-106 | 2 | 928/1053 | — |
| TSS, TS8 (RH) | 1982 | R2934/7 | 34mm | 376/100-230 | 124/026-20 | 2928/122-106 | 2 | 2928/060-3.5 | — |
| TSS, TS8 (LH) | 1982 | L2934/8 | 34mm | 376/100-230 | 124/026-20 | 2928/122-106 | 2 | 2928/060-3.5 | — |
| TR65SS, TR7T | 1981–82 | R930/108 | 30mm | 376/100-240 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| TR65T | 1981–82 | R930/109 | 30mm | 376/100-240 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| TR7RV | 1973 | R930/89 | 30mm | 376/100-270 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| TR7V, TR7RV | 1974–83 | R930/94 | 30mm | 376/100-270 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| Harris TR7 | 1985–87 | R1930/94 | 30mm | 376/100-270 | 124/026-25 | 622/122-106 | 1 | 928/1053 | — |
Triumph 750 Triples
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| T150 Trident (RH) | 1969–70 | R626/14, R626/16 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| T150 Trident (LH) | 1969–70 | L626/15 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| T150R Trident (RH) | 1971 | R626/47, R626/49 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150R Trident (LH) | 1971 | L626/48 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150R Trident (RH) | 1972 | R626/61, R626/63 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150R Trident (LH) | 1972 | L626/62 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150V Trident (RH) | 1973–74 | R626/66, R626/68 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150V Trident (LH) | 1973–74 | L626/67 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150 Hurricane (RH) | 1973 | R626/69, R626/71 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T150 Hurricane (LH) | 1973 | L626/70 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| T160 Trident (RH) | 1975–76 | R626/76 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-4 | — |
| T160 Trident (LH) | 1975–76 | L626/77 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-4 | — |
BSA Jetting Reference
BSA A Series 500–750cc
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| A10 Super Rocket & Spitfire Scrambler (USA) | 1962–63 | 389/47 | 1 5/32″ | 376/100-290 | 376/076-25 | 376/072-106 | 2 | 389/060-3 | — |
| A10 Super Rocket & Rocket Gold Star | 1963 | 389/94 | 1 5/32″ | 376/100-310 | 376/076-25 | 376/072-106 | 2 | 389/060-3 | — |
| A50 Twin | 1961 | 376/282 | 1″ | 376/100-250 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| A50 Star (Home) | 1962–65 | 376/282 | 1″ | 376/100-250 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| A50 Cyclone | 1964–65 | 376/316 | 1 1/16″ | 376/100-170 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | — |
| A50 Cyclone (USA) | 1964–65 | 376/310 | 1 1/16″ | 376/100-170 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | — |
| A50 Wasp | 1966 | 389/227 | 1 1/18″ | 376/100-200 | 376/076-25 | 376/072-106 | 2 | 389/060-3.5 | — |
| A50 Royal Star | 1966–67 | 376/321 | 1″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| A50 Royal Star (USA) | 1966–67 | 376/319 | 1″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| A50 Royal Star | 1968 | R626/7 | 26mm | 376/100-200 | 124/026-25 | 622/122-106 | 2 | 622/060-3.5 | — |
| A50 Royal Star | 1969–70 | R626/19 | 26mm | 376/100-200 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| A65 Star (USA) | 1962–63 | 389/70 | 1 1/8″ | 376/100-310 | 376/076-25 | 376/072-107 | 2 | 389/060-3 | — |
| A65 Star (Home) | 1962–65 | 389/67 | 1 1/8″ | 376/100-300 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| A65 Rocket (Home) | 1963–65 | 389/201 | 1 1/8″ | 376/100-300 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| A65 Rocket (USA) | 1964–65 | 389/202 | 1 1/8″ | 376/100-320 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| A65L Lightning Rocket (RH) | 1964–65 | 389/206 | 1 1/8″ | 376/100-220 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| A65 Mk II Spitfire (RH) | 1966 | T10GP2 | 1 5/32″ | 376/100-260 | 376/076-25 | 316/065-107 | 2 | 316/01055 | 510/1 |
| A65 Lightning & Hornet | 1966–67 | 389/229 | 1 5/32″ | 376/100-270 | 376/076-25 | 376/072-106 | 4 | 389/060-3 | — |
| A65 Thunderbolt | 1966–67 | 389/233 | 1 1/8″ | 376/100-300 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| A65 Thunderbolt (USA) | 1966–67 | 389/234 | 1 1/8″ | 376/100-310 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| A65 Mk III Spitfire (RH) | 1967–68 | R932/1 | 32mm | 376/100-190 | 124/026-20 | 622/122-107 | 2 | 928/060-3 | — |
| A65 Mk III Spitfire (LH) | 1967–68 | L932/2 | 32mm | 376/100-190 | 124/026-20 | 622/122-107 | 2 | 928/060-3 | — |
| A65 Thunderbolt | 1968 | R928/2 | 28mm | 376/100-230 | 124/026-20 | 622/122-106 | 1 | 928/060-3.5 | — |
| A65L Lightning & Hornet (RH) | 1968 | R930/21 | 30mm | 376/100-190 | 124/026-20 | 622/122-106 | 3 | 928/060-2.5 | — |
| A65L Lightning & Hornet (LH) | 1968 | L930/22 | 30mm | 376/100-190 | 124/026-20 | 622/122-106 | 3 | 928/060-2.5 | — |
| A65T Thunderbolt | 1969–70 | R928/6 | 28mm | 376/100-230 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| A65 Lightning (RH) | 1969–70 | R930/34 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A65 Lightning (LH) | 1969–70 | L930/35 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A65SS & A65SF Firebird Scrambler (RH) | 1969–70 | R930/34 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A65SS & A65SF Firebird Scrambler (LH) | 1969–70 | L930/35 | 30mm | 376/100-180 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A65SS Firebird Scrambler (RH) | 1971 | R930/72 | 30mm | 376/100-220 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A65SS Firebird Scrambler (LH) | 1971 | L930/73 | 30mm | 376/100-220 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A64 Lightning (RH) | 1971–72 | R930/70 | 30mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A64 Lightning (LH) | 1971–72 | L930/71 | 30mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A65T Thunderbolt | 1971–72 | R928/17 | 28mm | 376/100-230 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| A70 Lightning (RH) | 1971–72 | R930/78 | 30mm | 376/100-250 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A70 Lightning (LH) | 1971–72 | L930/79 | 30mm | 376/100-250 | Bush | 622/122-106 | 1 | 928/060-3 | — |
| A75R Rocket 3 (RH) | 1969–70 | R626/14 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| A75R Rocket 3 (LH) | 1969–70 | L626/15 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| A75R Rocket 3 (centre) | 1969–70 | R626/16 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3 | — |
| A75R Rocket 3 (RH) | 1971–72 | R626/61 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| A75R Rocket 3 (LH) | 1971–72 | L626/62 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| A75R Rocket 3 (centre) | 1971–72 | R626/63 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| A75R Rocket 3 (RH) | 1973 | R626/66 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| A75R Rocket 3 (LH) | 1973 | L626/67 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
| A75R Rocket 3 (centre) | 1973 | R626/68 | 27mm | 376/100-150 | Bush | 622/122-106 | 2 | 622/060-3.5 | — |
BSA B Series Singles 250–500cc
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| B25 Starfire | 1968–70 | R928/8 | 28mm | 376/100-260 | 124/026-25 | 622/122-106 | 2 | 928/060-3 | — |
| B25 Starfire | 1969 | R928/5 | 28mm | 376/100-180 | 124/026-25 | 622/122-106 | 2 | 928/060-3 | — |
| B25SS Gold Star, B25T Victor | 1971–72 | R928/20 | 28mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B25FS Fleetstar | 1968–70 | R928/10 | 28mm | 376/100-170 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B25FS Fleetstar | 1971–72 | R928/16 | 28mm | 376/100-170 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B29 | 1940–45 | 76P/1BB | 1″ | 4/042-160 | — | 4/061-106 | 3 | 6/0524 | 1BB |
| B31 | 1946–48 | 276AW/1BB | 1″ | 4/042-150 | — | 4/061-106 | 3 | 6/0524 | 1BB |
| B31 | 1949–54 | 276DR/1AT | 1″ | 4/042-150 | — | 4/061-106 | 3 | 6/0524 | 1AT (7°) |
| B31 (Home) | 1955–56 | 376/2 | 1″ | 376/100-260 | 376/076-30 | 376/072-106 | 2 | 376/060-3.5 | — |
| B31 Export (With Air Filter) | 1955–60 | 376/3 | 1″ | 376/100-200 | 376/073-30 | 376/072-106 | 2 | 376/060-3.5 | — |
| B31 (Home) | 1957–59 | 376/81 | 1″ | 376/100-260 | 376/076-30 | 376/072-106 | 2 | 376/060-3.5 | — |
| B33 | 1947–54 | 289G/1AT | 1 1/8″ | 4/042-200 | — | 29/076-106 | 3 | 29/0624 | 1AT (7°) |
| B33 (Home) | 1955–57 | 376/10 | 1 1/16″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| B33 (Home) | 1957–60 | 376/85 | 1 1/16″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| B40 (USA) | 1961–63 | 389/78 | 1 1/8″ | 376/100-160 | 376/076-30 | 376/072-106 | 3 | 389/060-3.5 | — |
| B40 MOD | 1960–61 | 376/253 | 1 1/16″ | 376/100-190 | 376/076-20 | 376/072-106 | 3 | 376/060-3 | — |
| B40 (Home) | 1962–66 | 376/28 | 1 1/16″ | 376/100-190 | 376/076-20 | 376/072-105 | 3 | 376/060-3 | — |
| B40 W.D. | 1967–68 | 398/6 | 26mm | 376/100-210 | 376/076-25 | — | — | 396/010 | — |
| B44 Victor Racing | 1965 | 389/221 | 1 5/32″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| B44 Victor Grand Prix | 1965–68 | 389/221 | 1 5/32″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 389/060-3.5 | — |
| B44 Victor Special | 1967–68 | R930/1 | 30mm | 376/100-220 | 124/026-25 | 622/079-107 | 3 | 928/060-3 | — |
| B44 Victor Special (USA) | 1969–70 | R930/38 | 30mm | 376/100-240 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B50SS Gold Star | 1971–72 | R930/62 | 30mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B50T Trail | 1971–72 | R930/62 | 30mm | 376/100-200 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B50MX Motocross | 1971–72 | R932/18 | 32mm | 376/100-250 | Bush | 622/122-106 | 1 | 928/060-3.5 | — |
| B50MX Motocross (TR5MX in USA) | 1973–74 | R932/28 | 32mm | 376/100-180 or 376/100-250 | Bush | 622/122-106 | 3 | 928/060-3.5 | — |
BSA Gold Star 500cc Singles
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| ZB32 Gold Star | 1949–54 | 276DR/1AT | 1″ | 4/042-150 | — | 4/061-106 | 3 | 6/0524 | 1AT (7°) |
| ZB32 Gold Star (Racing) | 1949–54 | T10TT9 | 1 1/16″ | 376/100-320 | — | 3970/109 | 4 | 175/3117 | 14/534 (7°) |
| BB32 Gold Star Clubmans | 1953 | T10RN | 1 3/32″ | 376/100-450 | — | 185/109 | 4 | 185/366 | 302/17 (Remote) |
| CB32 Gold Star Scrambles | 1954 | 10TT9 | 1 3/32″ | 376/100-350 | — | 3970/109 | 3 | 175/3117 | 302/10 (15°) |
| CB32 Gold Star Clubmans | 1954 | T10GP | 1 3/32″ | 376/100-210 | — | 316/065-109 | 1 | 316/0106 | 302/17 (Remote) |
| DB32 Gold Star Clubmans | 1955–61 | T10GP | 1 3/16″ | 376/100-280 | — | 316/065-109 | 4 | 316/0105 | 504/2 |
| ZB34 Gold Star | 1949–54 | T10TT9 | 1 5/32″ | 376/100-360 | — | 3970/109 | 4 | 175/3116 | 14/534 (7°) |
| BB34 Gold Star Clubmans | 1953 | T10RN | 1 3/16″ | 376/100-520 | — | 185/109 | 4 | 185/367 | 302/17 (Remote) |
| CB34 Gold Star Clubmans | 1954 | T10GP | 1 7/32″ | 376/100-260 | — | 316/065-109 | 2 | 316/0107 | 302/17 (Remote) |
| DB34 Gold Star | 1955 | T5GP | 1 3/8″ | 376/100-330 | — | 316/065-109 | 4 | 316/1047 | 302/17 (Remote) |
| DBD34 Comp Gold Star Scrambler | 1956–63 | 389/13 | 1 5/32″ | 376/100-320 | 376/076-25 | 376/072-106 | 2 | 389/060-3 | — |
| DB34 Gold Star Clubmans | 1956–61 | T3GP | 1 1/2″ | 376/100-350 | — | 316/065-109 | 3 | 316/4134 | 302/17 (Remote) |
| DBD34 Gold Star Scrambler (USA) | 1961 | 389/61 | 1 3/16″ | 376/100-320 | 376/076-30 | 376/072-106 | 4 | 389/060-4 | — |
| DBD34 Gold Star Catalina Scrambler | 1962–63 | 389/61 | 1 3/16″ | 376/100-320 | 376/076-30 | 376/072-106 | 4 | 389/060-4 | — |
| DBD34 Gold Star Clubmans (Home) | 1962–63 | T3GP2 | 1 1/2″ | 376/100-350 | 376/076-25 | 316/065-109 | 3 | 316/4134 | 510/1 |
BSA C Series Singles 250cc
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| C10 | 1946–53 | 274K/3A | 25/32″ | 4/042-90 | — | 4/061-105 | 2 | 4/0524 | 3A |
| C11 | 1946–48 | 274L/1AT | 25/32″ | 4/042-80 | — | 4/061-106 | 3 | 4/0524 | 1AT (7°) |
| C11G (Home & Export) | 1955 | 375/4 | 25/32″ | 376/100-140 | 376/076-25 | 376/072-105 | 3 | 375/060-3.5 | — |
| C15 Trials & Standard | 1959–61 | 375/34 | 7/8″ | 376/100-140 | 376/076-25 | 376/072-105 | 3 | 375/060-4 | — |
| C15 Competition Scrambler | 1959–60 | 376/222 | 15/16″ | 376/100-180 | 376/076-25 | 376/072-106 | 2 | 376/060-3 | — |
| C15 Scrambler & Starfire | 1960–61 | 376/258 | 1 1/16″ | 376/100-240 | 376/076-25 | 376/072-106 | 2 | 376/060-3.5 | — |
| C15 Star (Home) | 1961 | 376/270 | 1″ | 376/100-180 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
| C15 Police, Trials, Pastoral | 1962–67 | 375/51 | 7/8″ | 376/100-140 | 376/076-25 | 376/072-105 | 3 | 375/060-4 | — |
| C15 Sports Star (Home) | 1962–66 | 376/281 | 1″ | 376/100-200 | 376/076-25 | 376/072-106 | 2 | 376/060-4 | — |
| C25 Barracuda | 1967–68 | R928/1 | 28mm | 376/100-200 | 124/026-25 | 622/122-106 | 2 | 928/060-3 | — |
BSA D Series 125–175cc Singles (Bantam)
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| D1 Bantam | 1947–60 | 361/1 & 361/8 | 5/8″ | 4/042-75 | — | 259/069-106 | 2 | 161/0515 | Included |
| D1 Bantam Minor | 1957–61 | 361/18 | 5/8″ | 4/042-75 | — | 259/069-106 | 2 | 161/0515 | Included |
| D3 Bantam Major | 1954–58 | 523/1 | 11/16″ | 4/042-90 | — | 223/016-107 | 3 | 223/0125 | Included |
| D5 Bantam | 1958 | 375/31 | 7/8″ | 376/100-140 | 376/076-25 | 376/072-105 | 2 | — | — |
| D7 Bantam Super (Home & Export) | 1959–65 | 375/31 | 7/8″ | 376/100-140 | 376/076-25 | 376/072-105 | 2 | 375/060-3.5 | — |
| D7 De-Luxe and Silver Bantam | 1966 | 375/60 | 7/8″ | 376/100-100 | 376/076-25 | 376/072-105 | 2 | 375/060-3.5 | — |
| D10 Bantam | 1966 | 376/323 | 1″ | 376/100-180 | 376/076-15 | 376/072-105 | 2 | 376/060-3.5 | — |
| D10 Supreme, D10 Bushman, D10 Pastoral | 1967 | R626/3 | 26mm | 376/100-150 | 124/026-25 | 622/079-105 | 2 | 622/060-3 | — |
| D14/4 Supreme, D14/4B Bushman, D14 Pastoral | 1968 | R626/12 | 26mm | 376/100-160 | 124/026-25 | 622/079-105 | 2 | — | — |
| D14/4S Bantam Sports | 1968 | R626/13 | 26mm | 376/100-160 | 124/026-25 | 622/079-105 | 2 | 622/060-3 | — |
| D175 Bantam | 1969–71 | R626/17 | 26mm | 376/100-180 | Bush | 622/122-105 | 2 | 622/060-3.5 | — |
| D175 Bushman | 1969–71 | R626/17 | 26mm | 376/100-180 | Bush | 622/122-105 | 2 | 622/060-3.5 | — |
BSA M Series 500cc Singles
| Model | Year | Carb Spec | Bore | Main Jet | Pilot Jet | Needle Jet | Needle Pos. | Throttle Valve | Float Chamber |
| M20 | 1940–54 | 276C/1B | 1″ | 4/042-170 | — | 4/061-106 | 2–3 | 6/0524 | 1B |
| M20 | 1955–56 | 376/21 | 1″ | 376/100-240 | 376/076-30 | 376/072-106 | 3 | 376/060-5 | — |
| M21 | 1940–54 | 276BR/1B | 1 1/16″ | 4/042-160 | — | 4/061-106 | 2 | 6/0524 | 1B |
| M21 | 1955–56 | 376/23 | 1 1/16″ | 376/100-250 | 376/076-30 | 376/072-106 | 2 | 376/060-5 | — |
| M21 | 1957–61 | 376/88 | 1 1/16″ | 376/100-250 | 376/076-30 | 376/072-106 | 2 | 376/060-5 | — |
| M33 (Home) | 1957–60 | 376/85 | 1 1/16″ | 376/100-260 | 376/076-25 | 376/072-106 | 3 | 376/060-3.5 | — |
Shop Amal Carburettor Parts at JRC Engineering
JRC Engineering stocks Amal Concentric carburettors and jets for Triumph, BSA, and Norton vintage motorcycles. Whether you need a replacement main jet, needle jet, throttle slide, float chamber, or a complete new carburettor, we carry parts sourced from the same UK suppliers used by professional restorers.
- Concentric Carbs — MK1 and MK2 Amal Concentrics
- Amal MK2 Carbs
- All Amal parts by brand
- Monobloc Carbs
- Manifolds & Gaskets
Not sure which jet or carb spec fits your machine? Use the tables above to find your model and year, then contact our team — we’ve been supplying vintage British motorcycle parts for over 40 years.