Classic Motorcycle Build

Best Carb For Ironhead

Early Sportsters (1957-1965) were fitted with side-float Linkert DC carbs, which were simple units to diagnose and repair. The Linkert DC was also found on other Harley-Davidson models, including the 1957-1966 Servi-car, and one-year-only (1966) Shovelhead.

best carb for Ironhead

read Linkert DC Carburetor Rebuild

For those of you who ride an early Sportster, it's a rare bird and you'll probably want to keep it stock. If you have the original Linkert, leave it in place. But for those who have a later Ironhead, there's better carb choices.

Tillotson Carburetor

A switch to Tillotson was seen with the 1966 Harley Sportster and 1967 Shovelhead. Unlike the previous Linkert, it had an accelerator pump and featured a hydraulically operated automatic "economizer" circuit.

The Tillotson carb was complex and had many parts, and was not appreciated in its day. Lack of knowledge and poor parts availability tarnished their reputation, but when set up correctly, they are an excellent carburetor. The Tillotson Model HD was original equipment on Ironhead Sportsters until 1971, replaced by the simpler Bendix unit.

Bendix Carburetor

Originally fitted on 1972 to early 1976 Sportsters (and some Big-Twins), the Bendix carb is a popular choice for classic motorcycle builders and restorers who still ride their old scoots. They are relatively simple units that easy to tune and cheap to buy.

best carb for Ironhead

The three styles of Bendix Carb made for Harley V-twins are a 38mm fixed main jet, 38mm adjustable main jet, and 40mm adjustable main jet. Many riders feel they are the best carb for Ironhead Sportsters.

read Bendix Carburetor Rebuild

Keihin Carburetor

The Keihin carbs found on Ironhead Sportsters are fixed-venturi units, not to be confused with the later slide-type (CV) carbs found on 1988 and up Evo Sportsters. The first two years of Keihin-equipped Sportsters had issues (early 1976-1977), but by 1978 these were addressed and corrected. In 1979, venturi size went from 38mm to 34mm.

Mikuni Carburetor

The Mikuni is a slide-type carburetor, also known as a CV (constant velocity) carburetor. Back in the day when I was riding a 1972 XLCH Sportster, other Harley riders used to mock my 40mm Mikuni because it was Japanese, but it worked very well. To my delight and their surprise, the bike started consistently on the 1st or 2nd kick.

best carb for Ironhead

S&S Super B and Super E

When introduced in 1975, the S&S Super B was the carb to run. That was until the Super E came out in 1990. Although the Super E has gone on to become the best selling performance carburetor in the V-twin aftermarket, many riders still prefer the B over the newer E and G models, claiming it has better flow and more low end punch.

Super B carburetor on Sportster

read Tuning The S&S Super B

SU Carburetor

The SU was one of the first commonly available constant velocity "CV" carbs, and was a popular carb swap for Harley Panheads and Shovelheads back in the sixties and seventies. These variable-venturi carbs were originally found on European cars, such as Triumph, MG, Volvo, and others.

best carb for Ironhead

Measured by bore size, common SU carbs are the HS2 (1.25"), HS4 (1.5"), and HS6 (1.75"). For a 1,000cc Ironhead, look for one with a 1.25" bore.

Because some classic cars use SU carbs, air filters are still available. Back in the day, we would modify existing air filters to fit the odd 4-bolt pattern on the SU carb. This involved measuring and drilling holes in the backing plate.

Dual-Throat Carburetors

There's not too much more impressive than a dual-throat Weber sticking off your bike, but these carburetors are very time-consuming to dial in, simply because there's so many variable factors, and one adjustment usually affects others.

Adjustable items on dual-throat carbs include main venturi size, main jet, idle jet, air corrector jet, accelerator pump jet, emulsion tube, fuel inlet valve, and air horns. A dual-throat carb on a Sportster may cause interference with the rider's right knee.

best carb for Ironhead

The Mikuni-Solex pictured here is a car-type carburetor, but is gravity-fed like most motorcycle carbs.

Dual-Carb Ironheads

In 1984, H-D offered the XR-1000, featuring a pair of 36mm Dell'Orto carbs, which helped bring power output to 70-horsepower. The XR-1000 weighed in at 490 pounds. Top speed was about 125 mph.

Best Carb for Sportster

read 1980-1985 Sportster History

The Effects Of Ethanol Gas

Ethanol is used in today's gasoline as an additive, and E10 gasoline today contains roughly 10% ethanol. Ethanol has a shorter shelf and tank life than gasoline, and can begin to break down in as little as three weeks. Another problem with ethanol is that it attracts water and "breaks down" faster than gasoline.

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Ethanol is the same type of alcohol that is found in an alcoholic drink, which works somewhat like a cleaning agent - not good for an older engine. It also increases vapor pressure in gas, which may cause vapor lock in the carburetor. These issues are not so bad with daily transportation vehicles, but with small engines not driven regularly they are problematic.

Proper Gas Storage

Make sure that you store your gasoline properly and try to use it in a timely fashion. Use a product like Sta-bil and add it as directed. This will help prolong the life of the gas and keep it from harming your engine.

Fuel System Maintenance

If you store your bike over the winter, untreated fuel may go bad in as little as three months. Longer than that, a fuel system cleaning is recommended.

read Motorcycle Storage Tips

Octane Requirements (rule of thumb)

Only in theory are carburetors are simple devices.

read Carburetor Troubleshooting

read Kick-Starting An Old Motorcycle

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