How to Adjust the Valves on the Yamaha Raptor 700by William MachinUpdated November 07, 2017
Items you will need
Spark plug wrench
Metric socket and ratchet
Metric Allen wrenches
0.10-mm feeler gauge
0.18-mm feeler gauge
Periodic maintenance of your Yamaha Raptor 700 or 700R includes adjusting the valves for maximum engine performance and fuel efficiency. Possibly the most time-consuming part of the job is removing the seat, gas tank and the front fender fairing to access the valve covers at the top of the cylinder head. Those who are not familiar with the ATV should enlist the assistance of an experienced mechanic or follow the procedures in Chapter 3 of the service manual to remove these components. Adjusting the valves on a Yamaha Raptor 700 requires patience, attention to detail and a few hand tools.
Pull off the spark plug wire. Loosen and remove the spark plug with a plug wrench. Removing the plug eliminates engine compression so you can rotate the engine crank when adjusting the valves.
Loosen and remove the timing cover bolts at the right side of the engine with a metric socket and ratchet. Pull off the timing cover to access the timing flywheel and timing marks.
Use a metric Allen wrench to remove the crankshaft end-cover at the right side of the engine to access the crankshaft bolt.
Clean the area at the base of each valve cover with blasts from a compressed-air canister. This prevents dirt or off-road debris from getting into the valve springs and rocker arms.
Loosen and remove the pair of intake valve covers at the front of the cylinder head with an adjustable wrench. Loosen and remove the pair of exhaust valve covers at the rear of the head.
Attach a metric socket and ratchet onto the end of the crankshaft bolt where the end-cover was removed. Rotate the bolt counterclockwise as you observe the timing marks at the flywheel inside the timing housing. Rotate the bolt until the timing mark “I” is directly in line with the timing indicator at the upper side of the flywheel. This indicates the piston is at top-dead-center and the intake valves are fully closed.
Loosen the lock nuts at the base of both tappet stems on the intake valves.
Insert a 0.10 mm feeler gauge between the base of a rocker arm and the corresponding valve stem below. Turn the tappet stem clockwise or counterclockwise with the screwdriver, as necessary, until the feeler gauge slides in and out with light resistance. Repeat this step to adjust the other intake valve. Tighten both lock nuts with the wrench.
Attach the metric socket and ratchet onto the end of the crankshaft bolt. Rotate the bolt counterclockwise until the timing mark “I” is at the lower side of the flywheel and directly vertical to the timing indicator above. This indicates the exhaust valves are closed.
Loosen the lock nuts at the base of both tappet stems on the exhaust valves with the metric wrench.
Insert a 0.18 mm feeler gauge between the base of a rocker arm and the corresponding valve stem. Adjust both valves with the screwdriver until the gauge slides in and out with light resistance. Tighten the lock nuts with the metric wrench.
Reattach the valve covers and tighten each with the adjustable wrench. Reattach the timing cover and tighten the bolts with the socket and ratchet. Reattach the crank-bolt cover with the Allen wrench. Install the spark plug with the plug wrench and reattach the plug wire by hand.
Jiggle the corresponding rocker arms before adjusting the intake or exhaust valves. If necessary, rotate the crank a bit so the rocker arms are loose. This indicates the valves are closed completely, which is necessary for precise adjustment.
Disconnect one of the battery cables before adjusting the valves.
William Machin began work in construction at the age of 15, while still in high school. In 35 years, he's gained expertise in all phases of residential construction, retrofit and remodeling. His hobbies include horses, motorcycles, road racing and sport fishing. He studied architecture at Taft Junior College.