I have a 91 and it's time for a new chain and sprockets. I do a lot of long distance riding in top gear at about 85-90 mph and was wondering if it would be a good idea to run taller gearing for lower rpm and better gas mileage. Any suggestions?
I did this on my old FJ1200, but found that it made it harder on the clutch getting the bike out of the hole in first (granted, that bike only had a 5 speed) and also made slow speed riding in traffic a chore. It didn't really make that much difference on top (500 rpm IIRC), and I made a pretty dramatic change from 17/41 to 18/38. If you do change it, I'd recommend keeping it to maybe plus one on the front and only one or two down in the back. The advantage of adding one on the front is that it makes your chain bend less around the small sprocket, so less heat and less wear.
Later models pick up the speedometer reading off of the countershaft sprocket, so gearing changes will decalibrate your speedo. Not sure if a '91 still used the front wheel for speedometer...
3G's (mine is a 93) run the speedo drive off of the countershaft sprocket as opposed to the front wheel on a CBR (up to F2 IIRC) which has a speedo drive on the front axle. I just replaced it (initially) with a $10 bicycle speedo and pickup which I later replaced with a decidedly unsatisfactory Trail Tech computer (tach is a POS). The cable and drive was just too bulky without a fairing..... You could always add a magnetic bicycle pickup and speedo(mine's a Filzer DB4LW from MEC) for reference, at $10 it's a lot cheaper than a speedohealer or anything like that.
