Yamaha's versatile XS650 has been a favourite platform for many custom chopper and bobber builders since its introduction in the early '70s. While many customizers alter the XS650's frame to get that raked-out style, the motorcycle's front forks will need to be extended to complete the look. Extending the forks, however, used to be a major undertaking that required fabricating extended tubes or taking parts from other motorcycles. Fortunately, several manufacturers have begun to produce fork tubes with a 4-inch extension specifically for the XS650, simplifying the entire project to a minimum.
Park your XS650 on its centre stand, then place a jack stand under the motor to lift the front wheel off the ground. Unbolt the front brake caliper from the right fork leg, using a socket wrench and a 14mm socket. Unscrew the front axle nut with a 22mm wrench, then pull the axle out of the front fork and wheel.
Loosen the upper and lower fork clamp's pinch bolts with a socket wrench and a 12mm socket. Pull the fork legs out from the bottom of the fork clamps, using a twisting motion. Set one of the fork legs vertically in a soft-jawed vice.
Unscrew the nuts from the axle holders on the bottom of the fork legs, using a socket wrench and a 12mm socket. Pull the cap off the fork legs, then unscrew the bolt from the bottom of the fork's lower slider with a 6mm Allen wrench. Unscrew the top cap from the upper fork tube, using a 22mm wrench.
Pull the fork spring out from the top of the upper fork tube, then remove the fork leg from your vice. Pour the fork's oil out from the upper fork tube into a catch pan.
Unscrew the damper rod from inside of the fork tube, using a 9mm Allen head socket attached to socket extension. Pull the damper rod out of the fork leg. Place the fork leg back into your vice.
Pull the rubber boot off the top of the lower fork slider. Pry the retaining ring out from the top of the lower fork slider, where it meets the fork tube, using a small, flat screwdriver. Push the fork tube down, then pull it up forcefully to unseat the tube and the fork seal from the lower fork leg. Repeat until you can remove the tube completely.
Coat the new 4-inch extended fork tube and a new fork seal with fresh fork oil. Slide the fork tube into the lower fork slider. Drive the new fork seal into the lower fork slider, using a seal driver. Snap the retaining ring over the fork seal, then slide the rubber boot down the fork tube and onto the lower fork slider. Slide the damper rod into the fork tube, then screw it into place with your 9mm Allen head socket.
Fill the fork tube with 5.25 qts. of fork oil. Pump the fork tube several times to remove any air bubbles trapped in the fork oil. Slide the fork spring into the fork tube. Place a 4.75-inch length of schedule 80 PVC pipe over the spring. Screw the top cap onto the fork tube.
Install the remaining 4-inch extended fork tube onto the second fork leg, using the same method. Reinstall the fork legs onto your XS650, following the reverse method of removal.