07-24-2014, 06:31 PM
I installed a 17 tooth JT countershaft sprocket on my 2013 CB1100. The original 18/39 sprocket setup had the CB geared for 163.5 mph at 8500 rpm in fifth. The 17 tooth drops the theoretical top speed to 154.5 mph at redline. I also installed a small Trail Tech tachometer to double check my data. I set up the GPS and took a ride. My observations... First, the trade off of quicker acceleration vs higher revs on the highways is well worth it imho. At 70 mph indicated (69 mph GPS) the bike showed 4000 rpms with the 18 tooth sprocket. Now it shows 4250 rpms with the 17 tooth sprocket. Actual rpm with the 17 tooth sprocket at 70 mph GPS is 3850 rpms according to the TT tachometer. I checked this information with my gearing calculator after the ride and it was spot on for accuracy. This is the second TT tachometer I've had on a bike and I consider it a great $35 piece of gear. Btw, my CB idles at 1100 rpms 
The actual sprocket swap was pretty straightforward. With the bike on the center stand. Remove gearshift lever from shaft (make sure shifter is even with end of the shaft when you reinstall the bolt. There is a groove in the shaft splines for the bolt to slide through). Remove three hex head bolts to take off the plastic beauty cover. Remove two bolts from the sprocket cover and two from the clutch mechanism. Use a 14mm socket to loosen the bolt holding the sprocket in place. Press the rear brake lever to fix the sprocket in place. Once sprocket bolt is loose, use a 32 mm sprocket and a section of pipe to loosen the rear axle nut. Kick the rear tire forward a bit to put slack in the chain. Remove 18 tooth, install 17 tooth, adjust chain slack, reinstall other parts.
The actual sprocket swap was pretty straightforward. With the bike on the center stand. Remove gearshift lever from shaft (make sure shifter is even with end of the shaft when you reinstall the bolt. There is a groove in the shaft splines for the bolt to slide through). Remove three hex head bolts to take off the plastic beauty cover. Remove two bolts from the sprocket cover and two from the clutch mechanism. Use a 14mm socket to loosen the bolt holding the sprocket in place. Press the rear brake lever to fix the sprocket in place. Once sprocket bolt is loose, use a 32 mm sprocket and a section of pipe to loosen the rear axle nut. Kick the rear tire forward a bit to put slack in the chain. Remove 18 tooth, install 17 tooth, adjust chain slack, reinstall other parts.