Honda GL1800 2004 Owner's Manual page 211

Specifications
Engine Specifications
displacement
bore & stroke
compression ratio
spark plug
(standard)
spark plug
(cold climate)
spark plug (high
speed riding)
valve clearance
(cold)
spark plug gap
idle speed
Power Transmission
primary reduction
gear ratio, 1st
2nd
3rd
4th
OD
final reduction
final drive
204
Technical Information
111.8 cu-in (1,832 cm )
2.90 × 2.80 in (74.0 mm
9.8 : 1
BKR6E-11 (NGK)
K20PR-U11 (DENSO)
BKR5E-11 (NGK)
K16PR-U11 (DENSO)
BKR7E-11 (NGK)
K22PR-U11 (DENSO)
intake 0.006 in (0.15 mm)
exhaust 0.009 in (0.22 mm)
0.039 0.043 in (1.00 1.10 mm) −
700 70 rpm
±
1.591
2.375
1.454
1.068
0.843
0.686
2.750
shaft
× 71.0 mm)
or
or
or
−