Yamaha's newest Road Star 1602cc V-Twin incorporates hydraulic pushrods that reside in chrome tubes on the outside of the cylinder fins. Each pushrod operates rocker arms for intake and exhaust valves at each cylinder, and each rocker arm has a threaded adjuster that permits adjustment. Mechanical overhead valve motorcycle engines have specified clearances. Hydraulic valves are adjusted so that each set of exhaust and intake valves have the same clearance. In the event this type of mechanical work is new, you should enlist the services of a qualified mechanic to assist with adjusting the valves on a Yamaha Road Star motorcycle.
Place the bike on a stand or ask an assistant to hold it upright. Locate and remove three Allen bolts that secure instrument cluster. Lift the cluster and lay it back over the handlebars. Use a soft cloth to prevent scratching the finish.
Turn the fuel petcock at the underside of the gas tank to the "Off" position. Loosen the hose clamp that holds the fuel line to the petcock with a screwdriver. Pull the line of the petcock. Pull the vent tube off the top of the gas tank by hand.
Remove the metric bolts that hold the rider's seat to the frame of the motorcycle using a socket and ratchet. Remove the seat. Remove the metric bolt and nut that hold the rear of the gas tank to the frame. Unplug the green electrical connector at the rear of the gas tank. Lift the tank off the motorcycle and place it on a towel.
Pull two hoses off the top of the rear cylinder and fold them back, out of the way. Pull the spark plug wires off the spark plugs and secure them out of the way with nylon ties.
Remove the valve covers from both cylinders using an Allen wrench to loosen 14 bolts on each cover. Set the bolts and covers aside. Remove the spark plugs using a plug wrench and set the plugs aside.
Tap the engine starter in quick bursts as you observe the rocker arms on the forward side of one of the cylinders. This can be the front or rear cylinder. Notice the intake valve, located closest to the spark plug port, is pushed down and opened by the rocker arm. Continue to tap the starter until the rocker arm lifts up, allowing the intake valve to close.
Tap the starter in quick bursts again. Notice there is a short period when the rocker arm does not move. The valves are adjusted at this point, just after the intake valve has closed and the rocker arms don't move. Tap the started again if necessary to find this point.
Insert a feeler gauge between the top of the intake valve stem and the flat underside of the rocker arm above. Select another size gauge, if necessary, until the feeler gauge slides in and out with a bit of resistance. Note the thickness of this feeler gauge.
Locate the rocker arm at the exhaust valve on the opposite side, or rear of the cylinder. The exhaust valve is the furthest from the spark plug port. Insert the same feeler gauge between the top of this valve stem and the underside of this rocker arm.
Loosen the adjuster nut at the base of the threaded adjuster counterclockwise with a metric open-end wrench. Turn the adjuster on this rocker arm clockwise or counterclockwise as needed with a screwdriver until the feeler gauge slides in and out with a bit of resistance. Tighten the lock nut clockwise. Repeat the adjustment procedure to adjust the remaining valves.
Items you will need
- Allen wrenches
- Metric sockets and ratchet
- Nylon ties
- Feeler gauge
- Metric open-end wrench
- The small amount of valve clatter you may hear with the engine running is normal. Alternative adjustment procedures using a dial gauge require expert knowledge of the application.
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