In 1957 the FLE and FLEF traffic combination  models are discontinued leaving only the FL,FLF,FLH and FLHF models.
1957 featured new round Lucite tank emblem. this emblem and a new fender tip were Harley’s first use of plastic for emblems.
Engine changes include steel alloy valve guides replacing the bronze, exhaust guides are threaded to trap oil,
shorter push rods with longer adjusters,stronger valve springs.
big Bertha saddlebags are optional in 1957 only.

1957 sales brochure
1957 sales brochure

 

Here are some great sources for detailed information about Harley Davidson’s 1957 Panhead

How to restore your Harley-Davidson by Bruce Palmer 111

Riding vintage website

the Jocky Journal web forum

hydra-glide.com The panhead and flathead site

The Harley Davidson Panhead service manual 48-57 rigid

1957 models

modelengine typeactual displacementcompressionoptions
FL sport solo74 c.i.high compression73.66 c.i.7.25:1
FLF sport solo footshift74 c.i.high compression73.66 c.i.7.25:1F=foot shift
FLH super sport solo74 c.i.high compression73.66 c.i.8.0:1
FLHF super sport solo foot shift74 c.i.high compression73.66 c.i.8.0:1F=foot shift

NOTE: the ” F denoting foot shift will not be stamped in serial number.

1957 models available colors

paintstripesspeedometer
*blackWarner speedo with italic “Day-Glo” green numbers and hash marks with gold painted center
*pepper red
*skyline blue
*birch white
P police white
P police silver
*metallic midnight blue
pepper red/black tank panels
black/pepper red tank panel
skyline blue/birch white tank panels
birch white/black tank panels
* metallic midnight blue/birch white tank panels

*= extra charge

* =standard color could be ordered without tank panels at no extra charge.

P =police only

*black

1948 panhead black paint color

*pepper red

*skyline blue

*birch white

1948 panhead police white paint color

P police white

P police silver

1948 panhead police silver paint color

*metallic midnight blue