Oooh, I know this! From my notes.
Brakes:
1980 & 1981: Single pistons in all brake calipers.
1982 & 1983: Double pistons in all brake calipers.
1983 was the only GL1100 with linked brakes.
Aspencade models had drilled rotors.
Tires:
1980 & 1981: 110/90-19 front tire, 130/90-17 rear.
1982 & 1983: 120/90-18 front tire, 140/90-16 rear.
The weight rating of tires changed after 1981 to be slightly more.
Forks:
1983 had anti-dive forks.
Neutral safety switch:
1980 & 1981 had it on the block. 1982 & 1983 had it on the front transmission cover.
Gearing:
1980 & 1981 had identical gearing. Gearing got taller for 3rd, 4th and 5th in 1982. 1983 continued with the same taller gearing for 3rd, 4th and 5th, but changed 1st to be shorter. 1983 also changed the secondary reduction gearing to be taller. Final drive remained the same on all years.
Or, to summarize, the 1982 had slightly lower RPMs at highway speeds. The 1983 was lower still. Not much of a difference though, a few hundred RPMs at most.
Here's a link to a gearing chart.
Rear Suspension:
1981 - 1983 models had a rear suspension that could take slightly more PSI than the 1980 model.
1982 & 1983 Aspencades had an onboard compressor that could adjust the rear suspension pressure.
1983 models had stronger rear springs in the back shocks.
Carbs:
1980 & 1981 models have pressed in idle jets. 1982 & 1983 have removable idle jets.
Dash:
1983 Apenscades had a digital dash.
Wheels:
1983 Aspencade had alloy wheels instead of Comstar wheels.
Engine crash bars:
1980-1981 had different crash bars than the 1982-1983 models.
Turn signals:
1982+ had self-cancelling turn signals on all models.
Choke:
1983 had the choke lever by the left handlebar grip.
Models:
1980 & 1981 had the standard and Interstate models. Didn't pay close attention to this, but I believe both years are similar for the Interstate model.
1982 introduced the Aspencade model in addition to the standard and Interstate models.
