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YFZ450 Exhaust Cam Retard Page 2
STEP SIX: Remove the four exhaust cam journal bolts, shown in the photo. Use a criss-cross patern, loosening each one a little at a time. Place a clean rag inside the timing chain housing to prevent parts from falling into the motor. Once done, gently pull the cam journal cap off. Be careful, as there is a metal half-moon retainer that will fall out. Be sure to keep an eye on this as you lift the journal cap off. Place the half-moon retainer back into the journal cap, as shown here. Note the direction in which it sits carefully. Repeat this entire step with the intake cam.
STEP SEVEN: Tie the timing chain up to the frame using string or a "Zip-tie", like we did here. This will prevent it from falling down into the motor. Take the exhaust cam itself and tilt it forward towards you while pulling the timing chain off the sprocket to gain as much slack as possible, so you can rotate the exhaust cam clockwise. This will be tricky, and you'll have to tilt the intake cam also a bit. Take your time until you have the exhaust cam rotated on the timing chain one tooth. When done right, the mark you made on the timing chain will now line up with the factory "B" mark on the sprocket, like shown in the photo. The marks made on the intake cam sprocket and timing chain should remain the same.
STEP EIGHT: Detach the timing chain from the frame, and coat both cams thoroughly with motor oil, including the timing chain and sprockets. Insert the half-moon retainers on both cams (make sure they are seated in the proper direction), and re-install both cam journal caps with bolts. Using a torque wrench, slowly tighten each bolt a little at a time in a criss-cross pattern, to 7.5 ft/lbs each.
STEP NINE: Remove the 10mm center bolt from the automatic timing chain tensioner. Inside the bolt hole is a flat-head screw that you need to turn clockwise. Use a very small screwdriver for this. While turning, the mechanism on the opposite side will be retracting in. When done, it will be fully compressed inside and will stay that way. Then, simply re-install the entire assembly back into the cylinder with the two 8mm bolts. Once that is complete, take your small flat-head screwdriver and turn the inside screw slightly, this time counter-clockwise. This will release the mechanism and tighten your timing chain, automatically. Insert center bolt and tighten.
STEP TEN: Finally, turn your motor over again a few times like you did in Step 3. If everything looks fine and it turns smoothly, you can start putting everything back together. Re-install the two caps in your flywheel cover, and then your valve cover (with rubber gasket in place) using the two allen-head bolts. Attach the two hoses you removed in Step 1 along with your spark plug and spark plug cap. Throw your gas tank on, and you're ready to run!
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TECH
