Whats What : a quick guide through Harley-Davidson racing models
KR: 1952 to
1969, AMA Class C Flat Tracker, side valve 45ci, 750cc, unit construction,
rigid rear end, no brakes, Wico then Fairbanks-Morse horizontal magneto (in
1955) in front, ball bearing engine. Superseded by Iron XR 750.
KRTT: 1952 to 1969, AMA Class C Road Racer or
TT Racer,
side valve 45ci, 750cc, unit construction, front and rear suspension, brakes,
Wico then Fairbanks-Morse (in 1955) horizontal magneto in front, ball bearing
engine. Superseded by Iron XR 750
KRM: 1953 only, Desert Racer, side valve 45ci, 750cc,
unit construction, front and rear suspension, brakes, Wico vertical magneto,
roller bearing engine. Superseded by KHRM.
KHRM: 1954 to 1957, Desert Racer, side
valve 55ci, 888cc, unit construction, front and rear suspension, brakes, Wico
then Fairbanks-Morse (in 1955) vertical magneto, roller bearing engine.
Superseded by Sportster XLC/XLCH
KHR: side valve 55ci, 888cc,
unit construction, Wico then Fairbanks-Morse horizontal (in 1955) magneto in
front, ball bearing engine, probable existence or made by racers for non-championship
events. Superseded by Sportster XLR
KHRTT: 1954 to 1957?, AMA Class C TT Racer
for 80ci category, side valve 55ci, 888cc, unit construction, front and
rear suspension, brakes, Wico then Fairbanks-Morse (in 1955) horizontal magneto
in front, ball bearing engine. Superseded by Sportster XLRTT
XLR: 1958 t0 1969, 55ci, 883cc, OHV unit
construction, rigid end, no brakes, Fairbanks-Morse horizontal magneto in
front, ball bearing engine, probable existence or made by racers for non
championship events. Superseded by Iron XR 750,
XLRTT: 1958 to 1970, AMA Class C TT Racer
for 80ci then 900cc category, 55ci, 883cc, OHV unit construction, unit
construction, front and rear suspension, brakes, Fairbanks-Morse horizontal
magneto in front, ball bearing engine. Last year with iron XR cycle part.
Superseded by Iron XR 750
Model XLC Sportster, 1958 only,
Desert Racer, 55ci, 883cc, OHV low 7.5 to 1 compression, mild XL cams,
unit construction, front and rear suspension, brakes, Fairbanks-Morse vertical
magneto, no lights/generator.
Model
XLCH Sportster, 1958 only, Desert Racer, 55ci, 883cc, OHV high 9 to 1
compression, mild XL cams, unit construction, front and rear suspension,
brakes, Fairbanks-Morse vertical magneto, no lights/generator. Mild XL cams
Model XLCH Sportster, 1959 to 1969,
Street model, 55ci, 883cc, OHV high 9 to 1 compression, ramped P cams,
unit construction, front and rear suspension, brakes, Fairbanks-Morse vertical magneto,
generator and direct lights (no battery).
Iron XR 750, 1970 & 1971, Flat Tracker
& TT Racer,
45ci, 750cc, OHV unit construction, cast-iron Sportster CH based top end, front
and rear suspension, Fairbanks-Morse horizontal magneto in front, ball bearing
engine. A rare factory backed XRTT version was also made for Road Races.
Superseded by Alloy XR 750
Alloy XR 750, 1972 until 1980 (all H-D made), until
1990 (H-D assembled engine only), until present (H-D unassembled
engine), Flat Tracker & TT Racer, 45ci, 750cc, OHV unit
construction, alloy top end, front and rear suspension, Fairbanks-Morse
horizontal magneto in front then electronic ignition, ball bearing/super-blend
roller engine. A rare factory XRTT version was also made for road races
in 1972, used on and off until the end of the 70s.
