K&L 18-2457 Carburetor Rebuild Kit for Triumphs with Keihin Carbs
The K&L 18-2457 is a basic rebuild kit for one Keihin CV carburetor on carbureted Hinckley Triumphs. It fits the air-cooled Bonneville, T100, Thruxton, Scrambler, America, and Speedmaster twins, and later Keihin-equipped Thunderbird, Adventurer, Legend TT, Sprint, Trident, Tiger 885, and Trophy models. It replaces the parts that wear out or get damaged whenever the carbs are cleaned or opened up: the float needle, the float bowl gasket, the idle mixture screw, and the small seals. If your Triumph is hard to start, idles rough, floods, leaks fuel, or has been sitting, this kit is the starting point for a proper carb clean and rebuild.
K&L economy carburetor repair kits are made in Japan and contain the parts needed to rebuild one original carburetor body. This listing is for one kit, which services one carburetor. Jets and jet needles are not included, so you can reuse good original jets or choose the sizes you need.
Specifications
- Manufacturer: K&L Supply
- K&L part number: 18-2457
- British Iron part number: MBI-182457
- Fits Keihin carb assemblies: T1240122, T1245030
- Quantity: One kit (rebuilds one carburetor)
- Country of manufacture: Japan
- Shipping weight: 0.15 lb
What’s in the Kit
- Float bowl gasket
- Float needle (float valve)
- Pilot (idle mixture) screw
- Pilot air screw
- Flat washer
- Two O-rings, assorted sizes
Not included: main jets, pilot jets, jet needles, needle jets, slide diaphragms, or instructions. Compare the new parts with the old ones before you throw anything away.
When Your Keihin Carbs Need Rebuilding
- The bike is hard to start, idles rough, or stumbles just off idle.
- Fuel leaks from the overflow or vent hoses, or the engine floods when parked.
- The engine runs rich (black plugs, poor mileage) or lean (popping, hesitation, running hot).
- The idle mixture can’t be adjusted to a steady idle.
- The bike has been stored with fuel in the float bowls, leaving varnish in the jets and passages.
- You’re removing the float bowls for any reason. The old gaskets usually don’t reseal.
Fitment for this Triumph Keihin Carburetor Rebuild Kit
- Adventurer 900 (after 62507)
- America, Bonneville T100 (air cooled)
- Legend TT (after 62393)
- Scrambler
- Speedmaster
- Sprint (after 55881)
- Thruxton (air cooled)
- Thunderbird 900 (after 62393)
- Tiger 885 (after 55615)
- Trident (after 55880)
- Trophy (after 29156)
See the “Fit for the Following Vehicles” tab for the complete year, make, and model list. Models listed with “after” a number changed from Mikuni to Keihin carburetors at that serial number. Earlier bikes with Mikuni BST carbs need a Mikuni kit instead. If you aren’t sure which carbs you have, look for the Keihin or Mikuni name cast into the carburetor body. Fuel-injected 2008-on Bonnevilles, Thruxtons, and Scramblers don’t use carburetors, so this kit doesn’t fit them.
Rebuilding Triumph Keihin CV Carburetors
The factory service manual has the full step-by-step disassembly. These tips cover the most common problems:
- Leave the carbs joined unless you have to separate them. You only need to split the carb bank to replace the throttle shaft seals or the fuel and vent pipe O-rings.
- Replace the float needle and check the seat. On Keihin CV carbs the seat can’t be replaced. If a new needle still leaks, gently lap the seat with a cotton swab and 220-grit or finer lapping compound, then clean out every trace of compound.
- Clean the pilot circuit. Use a single strand of copper wire to clear the pilot jet, not a tip cleaner, which can damage the jet. Then flush the mixture screw passage and the transfer ports (the small holes under the throttle butterfly) with carb cleaner and compressed air.
- Install the new mixture screw with its O-ring. A missing or bad O-ring causes a lean idle that can’t be tuned out. On EPA-sealed carbs you may have to drill out the plugs over the mixture screws first. Many 1996-2008 49-state bikes had the plugs removed at the dealer.
- Check the slide and diaphragm. The slide should move smoothly, and the diaphragm should have no pinholes or tears.
- Set the float level and fit the new float bowl gasket. Triumph’s spec for Keihin carbs is a fuel level 1.5mm (plus or minus 1mm) above the float bowl gasket surface.
- Bench sync, set the mixture screws, then synchronize. Start with the mixture screws 1.5 to 2 turns out, then synchronize the carbs with the engine warm, using a carb synchronizer or manometer.
For the full process with photos, read Mike Grage’s Hinckley Triumph CV carburetor cleaning and tuning guide. If you’re bringing a stored bike back to life, start with his Hinckley Triumph barn find guide.
Related Keihin Carburetor Parts and Tools
Order one rebuild kit per carburetor, plus any parts your inspection shows you need. Spare K&L Keihin float needles (MBI-188953) are sold individually. The K&L float bowl drain screw (MBI-183720) makes draining the bowls before storage easier. Main and pilot jets for Keihin CVK carbs, float bowl gaskets, and carb seals are on our K&L parts page. For carb synchronization, see the Motion Pro carburetor synchronizer in our engine tools collection.
California notice: This Triumph Bonneville Carburetor Rebuild Kit is not available for sale in nor shipment to California. The California Air Resource Board (CARB) prohibits the sale of this item per California Code of Regulations, Title 13 § 2220 et seq., California Code of Regulations, Title 13 § 2470 et seq., California Vehicle Code §§ 27156 and 38391, and California Health & Safety Code § 43151 et seq. CARB Enforcement Advisory
The product images shown are for illustrative purposes only and may not be an exact representation of the product received. Manufacturers occasionally make minor cosmetic changes to items, such as color, finish, label, or design. These changes do not impact the item’s function or compatibility. Please contact us if you have specific concerns regarding appearance.
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Frequently Asked Questions
What does the K&L 18-2457 carb rebuild kit fit?
It fits the Keihin CV carburetors on carbureted Hinckley Triumphs: air-cooled Bonneville, T100, Thruxton, Scrambler, America, and Speedmaster twins, plus Keihin-equipped Thunderbird 900, Adventurer, Legend TT, Sprint, Trident, Tiger 885, and Trophy models. It fits Keihin carb assemblies T1240122 and T1245030.
What’s included in the K&L 18-2457 kit?
One kit includes a float bowl gasket, a float needle (float valve), a pilot (idle mixture) screw, a pilot air screw, a flat washer, and two O-rings. That’s enough to rebuild one carburetor.
Does the kit include jets?
No. K&L’s economy carb kits don’t include main jets, pilot jets, or jet needles. Clean and reuse the original jets if they’re in good condition, or buy replacement Keihin CVK main and pilot jets separately.
How many kits do I need?
You need one kit per carburetor: two for the air-cooled twins, three for the triples, and four for the four-cylinder Trophy 1200. Rebuilding every carb at the same time keeps them consistent and makes synchronization easier.
When should I rebuild my Triumph’s Keihin carbs?
Rebuild them when the bike is hard to start, idles rough, stumbles off idle, floods or leaks fuel, or runs too rich or too lean. A bike that’s been stored with fuel in the float bowls almost always needs one. Fit new float bowl gaskets any time the bowls come off.
Will this kit fit Triumphs with Mikuni carburetors?
No. Earlier Hinckley triples with Mikuni BST carbs use different parts and need a Mikuni kit. Models listed with “after” a serial number switched to Keihin carbs at that number. Check the carb body for the Keihin name if you aren’t sure.
Does it fit fuel-injected Bonnevilles, Thruxtons, or Scramblers?
No. This kit is only for carbureted models. Air-cooled Bonnevilles, Thruxtons, and Scramblers changed to fuel injection starting in 2008, depending on the model and market, so check that your bike has carburetors before ordering.
Can I replace the float needle seat on Keihin carbs?
No. The seat on Triumph’s Keihin CV carbs is part of the carb body. If the new float needle still leaks, clean up the seat with a cotton swab and 220-grit or finer lapping compound, then flush out all of the compound. Mike Grage’s CV carb cleaning and tuning guide explains how.
Where do I set the mixture screws after the rebuild?
Start with the mixture screws 1.5 to 2 turns out from lightly seated. Then fine-tune them with the engine warm at idle while synchronizing the carbs with a carb synchronizer or manometer, following your service manual.
Do I need to synchronize the carbs after rebuilding them?
Yes. Do a bench sync with the carbs off the bike so the throttle butterflies open evenly, then synchronize them with the engine running. The Motion Pro carburetor synchronizer in our engine tools collection works on two, three, or four carburetors.
Do I need to split the carburetors to rebuild them?
Usually not. You only need to separate the carb bank to replace the throttle shaft seals or the fuel and vent pipe O-rings. Otherwise, splitting the carbs adds a lot of time.
Can I ship this carb rebuild kit to California?
No. Under California Air Resources Board (CARB) rules, this item can’t be sold in or shipped to California.
*The product images shown are for illustrative purposes only and may not be an exact representation of the product received. Manufacturers occasionally make minor cosmetic changes to items, such as color, finish, label, or design. These changes do not impact the item’s function or compatibility. Please contact us if you have specific concerns regarding appearance.
