Famous American manufacturer introduced the FLH family of motorcycles in the early 1940s derived from the chassis of its touring lineup.
What Does FLH Mean on a Harley-Davidson Motorcycle? FLH is a model nomenclature by Harley-Davidson for its motorcycles since the 1940s. The first letter, F, indicates the 74-88 cubic inches engine, while L indicates the wider tires and hydraulic suspension. Furthermore, the third letter, H, shows high-performance or heavy-duty models.
Hydra Glide was the first FLH model with a different chassis design and hydraulically controlled front suspension rolled out in 1949. Later, several updates and new models became part of the lineup, including Duo Glide and Electra Glide.
We will discuss the different engine upgrades during these model years and their performance specifications.
Meaning of letters FLH on a Harley-Davidson motorcycle
FLH is a 3 letter model terminology introduced by Harley Davidson in the early 1940s for its touring motorcycles having specific engine models, displacement, and compression ratios.
The first letter F is for the motorcycles with 74-88 cubic inch (1200-1440 cc) Knucklehead engine design with 2 overhead valves.
The 2nd letter L indicates the wider front tires and hydraulic forks instead of the spring ones in the Hydra-Glide models in the series. It is also a notion of higher engine power at the expense of increased gasoline consumption. Due to larger tires, they also have larger fenders and forks to give them a giant appearance.
The 3rd letter, H, is for the high-performance or heavy-duty nature of these motorcycles due to the engine size and available power compared to their counterparts at that time.
Despite the engine changes and later upgrades, the FLH designation remains the same for the lineup, with some additional suffixes for later models.
The main variants of this Harley Davidson are Hydra Glide, Duo Glide, and Electra Glide, initially derived from its touring models in 1941.
Features of FLH motorcycles
Earlier models of the FLH lineup emerged from the touring series of Harley-Davidson in 1941 with several upgrades, new features, and engine changes.
The most prominent feature of these motorbikes’ is the big twin engines, which have 3 variants, including Knucklehead design in 1941-1947, Panhead in 1948-1966, and Shovelhead in 1967-1984. All these engine variants are air-cooled with electronic fuel injection.
Another essential feature is their compatibility with a 6-speed transmission in some latest models of the series.
Hydra Glide models introduced in 1949 have an upgraded suspension system. Earlier variants have spring suspension, while this series has a hydraulic mechanism on the front with telescopic forks.
Another significant feature is the introduction of batwing fairing or fork-mounted fairing on Electra Glide models. It reduces the air drag and protects the rider from wind and debris while riding.
They have dual disc brakes on the front wheel. Moreover, they have comfortable seats, backrests for long-distance riding, and ample storage compartments, such as saddlebags, for carrying personal items.
Updated Models of FLH Motorcycles
After introducing the Hydra-Glide model in the FLH family, there are 3 major upgrades. It includes the Duo Glide, Electra Glide, and Tour Glide.
The manufacturer discontinued some of these models. However, some, like Electra Glide, are still in production with updated features.
The Duo Glide is a motorcycle model produced from 1958 to 1964. It is part of the FL series of motorcycles.
The Duo Glide has had several technological advancements, including a new suspended frame with the help of a spring Coilover that allowed for a rear suspension to ensure a more comfortable ride.
It also has an updated telescopic fork front suspension, which improves handling and stability.
Moreover, you will also find the Panhead engine that is more powerful and efficient than the previous Knucklehead engine replaced in Hydra-Glide models.
These models have a new 2-speed transmission, allowing for effortless shifting without a clutch.
Duo Glide is one of the first American motorcycles to feature rear suspension and a hydraulic fork.
It is also the first Harley-Davidson motorcycle fitted with an electric start.
It is available in various colors and optional packages with chrome trim and other accessories. It is highly reliable and suitable for a comfortable and smooth ride.
It is the updated model of FLH motorcycles introduced in 1965 with some major upgrades in the Duo Glide variant.
Because of the electric starters, they were named Electra Glides by the manufacturer.
One of the prominent features of the Electra Glide update is replacing Panhead engines with the Shovelhead, which is more powerful, has better performance, and has improved payload capacity.
In addition, due to the presence of electric starters, its frame has a modified design to accommodate the 12V battery to crank the engine.
Electra Glide also has a batwing fairing introduced in the late 1960s that is easily removable, protects the rider from airborne hazards, and reduces air drag and wind friction.
However, later models have instruments fixed in the fairing. Therefore, you cannot remove them.
Other advanced features are front disk brakes and an increase in engine displacement from 1200cc to 1440 cc.
This brand manufactured the version of Electra Glide without fairing in 1997-1984 and 1989-1993, known as the FLHR Sport edition.
Its latest model is FLHR Road King, which is still in production, and you can get this sportier motorbike.
The Tour Glide is a part of FL Harley Davidson motorcycles, with the name changed from FLH to FLH because of its touring chassis.
Its salient features are a 1300-1440 cc engine, fixed fairing bolted with the frame, and compatible with 5-speed transmission.
Moreover, it has a modified front fork design to efficiently and safely handle the heavy frame and engine of the Tour Glide motorcycles.
In addition, it has rubber pads to support the Evolution engine that replaced the Shovelhead in 1984.
You will also find dual disc brakes on the front wheel, a comfortable seat and backrest for long-distance riding, and larger storage compartments suitable for touring.
After the discontinuation of FLH motorcycles in 1986, the FLT frame became standard for upcoming Tour Glide models.
The Tour Glide models remained in production till 1996 after their replacement by the Road Glide.
FLH motorcycles with Shovelhead engine
All FLH motorcycles from 1966-1984 have Shovelhead engines instead of Panhead designs. It has the name Shovelhead because of the shovel-shaped resemblance of its rocker covers.
The Shovelhead and Panhead are both V-twin engines used in these variants. Its salient features are extra power, efficient cooling and oil consumption, better fuel injection ports, and stronger construction.
In terms of performance, the Shovelhead engine is more powerful and reliable than the Panhead.
This is because it has larger valves and ports. The Shovelhead engine also has a better-designed cam and rocker arm system.
It is a part of the Electra Glide lineup of FLH motorcycles and has an electric starter with a 12V battery.
Moreover, it is also part of the special edition known as Harley-Davidson Confederate Edition.
It remained in service until replaced by the Evolution engine in Tour Glide motorcycles. Its displacement varied from 1210 cc to 1310 cc during its 18 years of production.