William Robison
Posts: 20269
Joined: 11/10/2002
From: Mary Esther, Florida, FL, USA
Status: offline
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F16FxR4real:
This is the best and most accurate way I've found to adjust the valves. Use it or not as you please.
With the rocker boxes off, turn the crank in its normal direction of rotation. You will see first the exhaust rocker move, then when it has almost returned to its starting position you will see the inlet rocker start to move. As you turn the crank past this point you will notice a slight difference in its feel, this is where the piston is at top dead center. Note the position of the crank, and turn it exactly one full turn. Now you are at top dead center again, but this time you have it between the compression and power strokes, and this is where you want the crank to adjust the valves.
You can now whip out your feelers and check/adjust if you want, but it may not be needed. If you can feel just a little bit of up and down wiggle when you grab the end of the rocker it's ok. But you wont know what "Just a little" is until you've done it a few times, so try the feeler. If the 0.003" slides in with no resistance it's too loose. Forget the 0.004" feeler. If the 0.003" is a little snug pull it out fast. If you hear a snap you had the valve pushed open - the snap is the valve closing. The springs are not strong at all.
But the snap doesn't mean the adjustment is too tight. If you felt the wiggle before you tried the feeler it's in specification. Leave it alone.
If you didn't hear the snap, or you had no wiggle, it's time to adjust the valve. And, as I said, forget the feeler for adjustment.
Loosen the locknut, and turn the adjuster screw back and forth a bit, be sure it turns freely. Now, starting from a loose position turn the screw in. You will feel it get a little harder to turn at some point, and if you keep turning it you will see the valve moving. Go back and forth with the screw until you can feel the point where the valve starts moving, and set it just to the point where the clearance is zero, but the valve has not moved. Then, without turning the screw at all, tighten the locknut. "But that's no clearance at all!" you say. Wrong. There is enough distortion of the threads from tightening the locknut that you now have about a half thousandth clearance. Wiggle the end of the rocker again, you'll feel the right amount of up and down wiggle.
I have, using a dial gauge, verified this method on several Saito, OS, and Magnum engines. I can't verify Enya 4c engines, I've never had one. But it should work on them as well.
In spite of what you may think, a feeler gauge is a very inaccurate method of valve adjustment, and the more the valve gear wears the less accurate it is. If anyone wants to argue the point I'll be happy to discuss it further. The only really accurate way to get a particular clearance is using a dial gauge. But, as I said to start with, on a model 4c engine any clearance is enough.
Bill.
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Saito 150 valve adjustment and idle - 
RE: Saito 150 valve adjustment and idle - 