May 172013
 
 

A Brief Comparison of the Most Popular Harley Davidson Engines

Complete Harley-Davidson motorcycles were manufactured in Milwaukee, Wisconsin, from 1903 through 1972. From 1972 through the present Harley-Davidson engines have been built in Milwaukee, then shipped to the York, Pennsylvania, plant where the balance of motorcycle components are manufactured and where final assembly takes place.

Model
Knucklehead
Shovelhead
Evolution
Twin Cam 88
Years Produced 1936 to 1947 1948 to 1965* 1966 to 1985 1984 to 1999 1999 to Present*
Models Available 1936 – 1952 —61” OHV EL
1937 – 1942 —80” UL
1937 – 1951 —45” WL
1941 – 1947 —74” FL
1942 – 1945 —45” WLA Army, XA 750cc Army
1948 ———74” FL Pan
1949 – 1957 74” Hydra Glide
1952 ———45” K
1954 ———55” KH
1957 – 1971 55” XL Sportster
1958 – 1963 FL Duo Glide
1965 – 1970 FL Electra Glide
1970 – 1971 – XR750 (1972-80 = Aluminum, 1981- ? engines only)
1971 – 1980 – FLH1200
1971 – 1972 – FX1200 Super Glide
1972 – 1976 – XLH, XLCH 1000cc
1972 ——— Sportster
1974 – 1980 – FXE 1200
1977 ———–FLHS
1977 – 1979 – XLT
1977 – 1978 – XLCR, FXS Low Rider
1978 ———-FLH80
1979 ———-FLH80 Classic, FXS 80, FXEF1200, Fat Bob
1980 ———-FXWG Wide Glide
1980 – 1982 – FLT Tour Glide, FLHS, XLS, FXEF80, FXB Sturgis
1981 – 1986 – FLT Classic
1982 – 1985 – XLS Roadster
1982 ———-XLHA, XLSA
1982 – 1983 -FXR, FXRS Super Glide II, FXSB Belt, FXRT Tour Glide (shovels)
1983 ———-FXDG Disc Glide
1983 – on—–FLHT, FLHTC
1984 – FXST
1984 – FXRDG – only year
1986 – FXR – re-introduced, FLST Heritage Softail
1987 – FXLR Low Rider Custom
1988 – FXSTS Springer Softail
1990 – FLSTF Fat Boy
1991 – FXDB Dyna Glide Sturgis
1992 – FXDB Daytona Dyna Glide – only year
1992 – FXDC Super Glide Dyna Custom
1993 – FXDWG Dyna Wide Glide, FXDL Dyna Low Rider
1995 – FXSTSB Bad Boy, FLHR Road King
In its first year, the Twin Cam 88 is on all the Touring and Dyna models, with the Softails following later.
Displacements 1936 Series E
Displacement 61 ci
Bore 3 5/16 inch
Stroke 3 1/2 inch1941 Series F
Displacement 74 ci
Bore 3 7/16 inch
Stroke 3 31/32 inch
E Series
Displacement 61 ci
F Series
Displacement 74 ci
XLH & XLCH (Sportster)
Displacement 55 ci
In 72 the Super Sportster had 1000ccAll other models had standard 74 ci powerplant untill the introduction of the 80 ci
Displacement: 80 ci
Bore: 3.498 inch
Stroke: 4.250 inch
Displacement: 88 ci 1450cc
Bore: 3.75 inch
Stroke: 4.00 inch
Compression Available in Low, Medium and High Available in Low, Medium and High   Compression Ratio: 8.5:1 Compression Ratio: 9.0:1
Head Design Whereas the flat head engine had the intake and exhaust valves on opposite sides of the combustion chamber the valves in the knucklehead were moved to the top of the combustion chambers. The panhead didnt change much from the knuckle in internals. But it came equipped with aluminum heads. Larger aluminum version of the Sportster head, with the same hemispherical combustion chamber and valve angle New aluminum heads designed to decrease oil leakage while utilizing side-squish combustion chambers and flat pistons Aluminum permanent mold with 85cc bathtub combustion chamber
Cylinder Design Cast Iron Aluminum cylinders have a lip on top of the barrel that fits into a recess on the head     50% more fin area for better cooling. Constructed of aluminum high-pressure die cast with cast in Spiney-Lok cast iron liner.
Case Design Introduced in 37 the recirculating dry sump oiling system. Later models included centrifugal bypass oil pump. Revised crankcases and cylinders feed oil internally to the heads and return  internally to the cases. In  1955 Harley modified the pans by installing a quieter more efficient lower end. In 65 they were the first HD’s to have electric start. Later introduction of rubber mounted engine A new lower end designed for electronic ignition for better spark control to meet emissions, something the shovel couldn’t do anymore. Twin ge-rotor, dry sump, internal oiling imported from the Sportster. Now uses an O ring instead of paper gasket on the base to cylinder. Stronger crankcase mounts. Counterbalanced crank to reduce the classic vibration.
Fuel Delivery Linkert carburetor on later models M-74B 1 1/2-inch Linkert carburetor on 74 ci   Keihin carb, EFI was introduced in 95 Carb or EFI
Transmission 61ci E models had separate 4sp trans constant mesh. Optional three-speed and three-speed-with-reverse transmissions with sliding-gear first on early models. All later Models were 4sp with optional side car gearing. Both E and F series were available with either hand or foot shifted 4sp transmissions Late introduction of 5sp trans on FLT model. By 1991 all models featured the 5sp transmission Within the transmission housing lies a new shift mechanism that delivers low-effort, clunkfree gear changes
Other The knucklehead motor was the first of the overhead valve motors and succeeded the side-valve flathead (although the latter continued in production throughout the knucklehead era and beyond). Basically the knucklehead lower end with a new top end with hydaulic valve lifters and aluminum cylinder headsFLH motors are fitted with Victory camshaft that has a higher lift   To this point the Evo was the most radical departure in engine design for HDIn 1992 belt drives were standard on all models. Twin cams with chain driven spring loaded tensioners Now the Twin Cam has surpassed the Evo in a departure from the design norm. Supposedly only 21 parts are common to the Evo, however, a press release states that fewer 18 parts are shared between the engines
Spotter’s Guide

Harle-Davidson Knucklehead Engine

Harley-Davidson Panhead Engine

Harley-Davidson Shovelhead Engine

Harley-Davidson Evolution "Evo" Engine

Harley-Davidson Twin Cam 88 "Twink" Engine

Special Notes * Main production models, does not include specialty models such as WL etc. The knuckle received it’s nick name by the appearance of the heads which look similar to the top of a hand. *Panheads had the longest production run of any Harley motor to date, lasting 17 years. The first Sportsters, introduced in 1957, were panheads. See the notes on Shovelheads as to why the shovel was not considered the longest production run.Received it’s nick name due to its valve covers look of an upside down cake pan. *There were two versions of the shovel: the generator or flatside shovel, and the cone motor shovel. The flatside shovel, was produced from 1966 to 1969. A generator was mounted ahead of the front cylinder, giving the motor a relatively flat look. Generator shovels are also referred to as “pan/shovels,” because the the lower end is the same as a panhead.   *The Twin Cam is also referred to as the Fathead in some circles.
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