Set the valves on my Wolverine and took notes. This procedure should work for the Yamaha Bruin, Warrior, and Wolverine 350 cc, air-cooled engine.

1. The engine must be about room temperature to properly measure the valve clearances.

2. Pull the front fender – lots of screws & bolts to remove. Careful with the headlight wires under the hood. The front bumper on a Wolverine must be removed – careful with the oil cooler lines.

3. Turn the gas valve off and slide back the hose clamp on the fuel line (pinch it with pliers). Disconnect the gas line by turning it with pliers, then pulling it off by hand. Remove the gas tank.

4. Remove the rubber membrane around the air-intake snorkel.

5. Clean any dirt from the valve covers, frame rails, cables, wiring, and other equipment above the valve cover openings. Wipe down with a damp rag. Don’t allow dirt inside the engine!

6. The valve cover to the rear is the intake valve. Remove the two 6 mm Allen screws. The valve cover on the front of the cylinder head (near the exhaust port) is the exhaust valve. Remove the three 6 mm Allen screws. Keep that stuff clean.

7. Look at the pull start side of the engine. In front of the starter cord you will see a round plastic plug with a slot for a wide, flat blade screwdriver. Clean and remove the plug – careful with the small o-ring.

8. Get a flashlight and look into the hole while you turn the motor with the starter cord. You will see a groove cut laterally in the threads of the plug hole - that is your reference mark. As you turn the engine, you will see marks on the flywheel. After the intake valve cycles down and up (and NOT following the exhaust valve), slowly pull the starter cord past the “F” mark to align the “T” mark (“F” is for spark plug fire). It doesn’t have to be perfect – if the “T” is in the window – that’s close enough. Ensure both valves are in the up position. If both valves are compressed slightly, you went too far – and need to go around one more turn of the crankshaft.

9. Slide your feeler gauge between the intake tappet and valve. Measure where it is, before adjustment, by determining what size feeler gauge will easily slide in, and the next bigger size feeler gauge that won’t. Do not adjust the valves - just see where they are at. And, it’s a good idea to record (and date) what you found in your owner’s manual. My Wolverine at the 20 hour check was between 4 and 5 on the intake, and 8 and 9 on the exhaust (both a bit loose).

10. Settings for 2005 Yamaha Wolverine valves:

Intake: 0.06 mm ~ 0.10 mm (0.0024 in ~ 0.004 in)
Exhaust: 0.16 mm ~ 0.20 mm (0.0063 in ~ 0.008 in)
Lock Nut Torque: 170 in-lbs (14 ft- lbs)

What that means is a 2/1000” feeler gauge should slip in between the intake valve and tappet easily, and a 4/1000” should not. If a 3/1000” gauge slides in, with friction (but not forced), that’s about perfect. On the exhaust valve, a 6/1000” gauge should slide in easily, an 8/1000” gauge should not, and you can verify with a friction-fit 7/1000”. Look on the air filter cover under the seat for a sticker with the correct valve settings for your 350 engine.

Valve adjustment lock-nut torque recommendations vary between Honda and Yamaha and from engine to engine, anywhere from 10 to 17 ft-lb. I prefer the middle range (14 ft-lb).

11. If the valves are within tolerance, then you did all the work for nothing, except to know your engine is well cared for. If the valves are way out of tolerance (shouldn't be more than a couple thousands off - either way), you may have more serious engine problems. Too tight or no clearance leads to burned valves. Loose clearance leads to clattering noise, and increased cam and rocker wear.

12. To adjust your valves, loosen the lock nut at the end of the rocker arm. The threaded shaft has a square end to hold. You can turn it with your fingers or a very small crescent while tightening the jam nut. A mere 1/8 turn of the adjuster screw will add or subtract about 3/1000”. When you are done adjusting the valve, hand-tighten the lock nut. You will find that depending on how snug the lock nut is after adjusting the valve, that the adjustment changes. Once you have the lock nut hand-tight, torque it to 14 ft- lbs (170 in-lbs) with the torque wrench. Check the adjustment to insure it did not change. If so, loosen the lock nut and readjust.

13. Reassemble in reverse order. Don’t forget the plug & o-ring on the pull-starter cover! And don’t over-torque the valve cover bolts (85 in-lb or 7 ft-lb), because they go into aluminum. No fun if you strip one of those!

14. You’re DONE!