SAFETY FIRST: Protective gloves and eyewear are recommended at this point.
Front Sprocket Removal
Remove the Phillips head screw holding the kickstand switch cover in place.
Remove the three bolts that secure the sprocket cover to the engine using a 10 mm wrench. Remove the sprocket cover.
Use a chisel and a hammer to bend the locking tab away from the sprocket.
Depress the rear brake to keep the sprocket from turning and loosen the sprocket nut using a 27 mm wrench.
You will need to loosen the rear axle nut and slide the rear wheel forward to gain slack in the drive chain in order to remove the sprocket from the transmission output shaft.
Some early KLR models do not have a sprocket nut, they use a sprocket plate held to the sprocket by two bolts. To remove the front sprocket on these models first remove the two bolts that secure the sprocket plate to the sprocket using a 10 mm wrench.
Rotate the sprocket plate to align the splines of the sprocket plate with the splines in the transmission and pull off the sprocket plate. Remove the sprocket.
Countershaft Seal Replacement
Remove the collar and O-ring and replace the seal as needed. Discard the O-ring. Remove the seal with a seal pick. Take care to avoid damaging the crankcase with the seal pick.
Lubricate the new countershaft seal lips with grease. Drive in a new countershaft seal with a driver that will fit over the shaft and has the same outside diameter as the seal. Coat the countershaft collar and new countershaft O-ring in grease. Install the O-ring and collar onto the countershaft. The oil grooves on the collar should face towards the right side.
Front Sprocket Installation
The sprocket should have a shoulder on one side. This shoulder should face the inside upon installation.
Install the front sprocket in the reverse order of disassembly. Tighten the sprocket nut to its proper torque specification and bend the locking tab back over the sprocket nut.
Front sprocket nut torque: 98 N-m or 72 ft-lb
On early model KLR650s, slide the sprocket plate onto the transmission shaft until it gets to the groove in the shaft and rotate it so that the holes in the sprocket plate line up with the bolt holes in the sprocket.
Torque the two bolts that secure the sprocket plate to the sprocket to specification.
Front sprocket plate bolt torque: 9.8 N-m or 87 in-lb