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I don't think adjusting the valves will help, Never seen a cam lobe increase in lobe height, or a lifter increase.[at the bottom] That low cyclinder could be a leaking valve. [as in a burnt valve] I have done this to check for a leaking valve. Remove exhaust header, Remove the intake elbow, Bring crank almost to top dead center, Remove sparkplug, Fill cyclinder with atf, install cyclinder pressure gage and manually turn the crank in normal rotation WATCH pressure gage do not exceed 80 psi and watch for the atf leak at the intake or exhaust ports. NOW REMOVE pressure gage and turn crank in normal rotation to remove the atf from the cyclinder, IF YOU feel UNCOMFERTABLE doing this DON'T do it. SERIOUS problems could result. Just my two cents worth, Charlie
 

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I don't think adjusting the valves will help, Never seen a cam lobe increase in lobe height, or a lifter increase.[at the bottom] That low cyclinder could be a leaking valve. [as in a burnt valve] I have done this to check for a leaking valve. Remove exhaust header, Remove the intake elbow, Bring crank almost to top dead center, Remove sparkplug, Fill cyclinder with atf, install cyclinder pressure gage and manually turn the crank in normal rotation WATCH pressure gage do not exceed 80 psi and watch for the atf leak at the intake or exhaust ports. NOW REMOVE pressure gage and turn crank in normal rotation to remove the atf from the cyclinder, IF YOU feel UNCOMFERTABLE doing this DON'T do it. SERIOUS problems could result. Just my two cents worth, Charlie
If a valve is too tight it will cause a low compression reading, valves do sink into the seats and decrease the clearance, or someone could adjust them too tight.
Never heard of that method of checking valves but it would work. Just wondering though, why would it hurt to exceed 80 psi?
 

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To answer your question about the 80psi, Adding the atf is making a hydraulic situation which is a brand new ball game, Air will compress as hydraulic oil will not. and you are correct about the valve seats, I have no clue what mother Honda used for their seats, Most automotive seat are made of stelite which are harder than the valve itself. I was just trying to be helpful for him to figure out his low compression on his ride without splitting the case. Just my 2 cents worth, Charlie
 

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To answer your question about the 80psi, Adding the atf is making a hydraulic situation which is a brand new ball game, Air will compress as hydraulic oil will not. and you are correct about the valve seats, I have no clue what mother Honda used for their seats, Most automotive seat are made of stelite which are harder than the valve itself. I was just trying to be helpful for him to figure out his low compression on his ride without splitting the case. Just my 2 cents worth, Charlie
The seats are in fact Stellite. The valves are Stellite coated which is why Honda does not like you to grind the valves. You would grind the Stellite off. :)
 

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I have never heard that the seats are stellite, just the valves. Grinding the seats is permitted by the manual.
 

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I have never heard that the seats are stellite, just the valves. Grinding the seats is permitted by the manual.
The reason you can grind the seats but not the valves is because the seats are solid stellite. You can't grind through the hard stellite like the valves. Most seats (maybe all????) on aluminum heads are Stellite.
 

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To answer your question about the 80psi, Adding the atf is making a hydraulic situation which is a brand new ball game, Air will compress as hydraulic oil will not.
My point is pressure is pressure, whether it's air or fluid. I know you wouldn't want to put too much pressure on it or you could bend a rod and 80 psi is plenty for the purpose but the combustion pressure far exceeds that without damage.
 

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Discussion Starter #28
If I suspect a burnt valve, I would just perform a leakdown test with an actual leakdown tester, which I own. Still haven't adjusted the valve, my antique truck blew a coolant line and then my sewer broke. I refuse to pay anyone to do anything, so I had to fix myself. Will be adjusting valves next week and retesting.

History of the bike is that it hates idle. PO was an idiot, carbs were literally put together with teflon tape around the main jets. My theory is that the bike sat up for a looooong time before I got ahold of it.
 

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If I suspect a burnt valve, I would just perform a leakdown test with an actual leakdown tester, which I own. Still haven't adjusted the valve, my antique truck blew a coolant line and then my sewer broke. I refuse to pay anyone to do anything, so I had to fix myself. Will be adjusting valves next week and retesting.

History of the bike is that it hates idle. PO was an idiot, carbs were literally put together with teflon tape around the main jets. My theory is that the bike sat up for a looooong time before I got ahold of it.
Billy,
Well there you go. Do a quality carb rebuild and with any luck that will fix the issue. A slightly lower compression on one cylinder will not make the bike run or idle bad in most cases. It is not worth worrying about. Lash the valves if you want but don't expect miracles.
 
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