The GL1100 evolved from the GL1000 and although a very different bike there are many parts, mainly engine, that are interchangeable. There has been many queries as to what parts will fit which bike.

For those interested, here's a breakdown:

Compatible GL1000 and GL1100 engine parts.

Rear belt covers

Belt covers, gaskets and bolts

Rocker box covers, gaskets and bolts

Rockers, rocker shafts with springs

Valves, springs, keepers and caps (not '83)

Belt tensioners and tension springs

Cam wheels, retaining bolts and keys

Top water transfer pipes, thermo housing, thermo cover and elbows

Oil pressure sensor, temperature sensor, fan switch

Front transmission cover (80-81 with rear ignition unit, not 82-83)

Water pump cover

Water pump

Oil pump

Pumps drive shaft

Main bearing shells

Most of the front shift mechanism

Neutral switch (80-81)

Cylinder heads (GL1100 left head needs to be modified for the points system)

Fuel pump

Tachometer drive

Output shaft

Alternator stator

Alternator rotor

Alternator shaft and damper, damper rubbers

Starter chain and sprockets

Starter clutch

Starter motor (1100 to 1000, not 1000 to 1100)

Oil pump chain and sprocket

Scavenge pump

Clutch (1100 clutch in 1000 may need 1100 clutch cover.)

Primary chain tensioner ( 1000 oil shield needs modifying)

Primary chain slider block

All gaskets except cylinder heads

Most of the internals do not interchange

You will hear 1100 pistons can be fitted into 1000 bored out. Boring the 72mm to 75mm leaves the liner only 1.5mm thick, with not much alloy behind to support. Not recommended.