Engine basics > Four strokes only
Stuck exhaust valve
Robertc:
Saito 91 with very stuck exhaust valve and also the tiny bolt that holds the rocker arm won't budge. Have tried heating to 250 degrees, putting WD-40 but still won't move. If I bang lightly on the rocker arm, can get the valve to open a tiny amount, but won't go back or open.
Any ideas?
Tim Wescott:
Aero-kroil is like WD-40 on steroids. I don't know how it works on castor, but on rust it's the bee's knees. If you're down to penetrating oil and heat, the best thing to do is to be patient and keep trying. You're hoping the oil will seep into some very narrow spaces, and that takes time. Spray, let it sit, heat it up, tap it gently, then repeat once or twice a day until you're either successful or so fed up you're ready to damage things to get it apart, and buy new pieces.
(Or -- eww -- hand it off to an engine expert).
Dan McEntee:
Yeah, this is a patience thing. Oil, some heat and some gentle pressure. Save the WD-40 for something else. Try the Kroil if you can find it near you, or for a spray can I like PB-Blaster, I think it's a good second choice to Kroil. I understand that ATF and acetone mix works pretty good also if you have no other choice. Mix 50-50. Cycle the heat and oil as you can. If get the valve to move by lightly tapping it, make sure you oil it again right away, heat it and try returning it to the original position. Then more heat and oil and go back the other way. The back and forth action will help. Patience and pressure and keep it oiled and you will get there.
Type at you later,
Dan McEntee
Tim Wescott:
Looks like there's a bazzilion places that carry Kroil mail-order. So if you don't mind doing that, you're all set.
Dennis Toth:
Robert,
It sounds like the valve stem could be bent and causing the valve to bind. I would first try some targeted heat from a small propane torch like a "Super Cub Propane Touch" or maybe even a candle lighter to heat just the head/valve guide area and see if it moves.
Best, DennisT
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