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Discussion Starter #1
Greetings,
My name is Nathan and I have an 82 Honda cx 500 that has all sorts of issues. It was barley running previously but the carbs were shot so I just got finished rebuilding them this week and slapped it all together. I have had a tapping noise and need some help as to where to get started to find it. My friends and I checked the valves (might recheck anyway) I know the carbs need to be tuned but I want to know if I am destroying the motor while running it to diagnose the issue.

Ole Tappy

Friends say its an exhaust leak but the tapping seams to disappear with higher rpms. I run a Buell XB so noisy motors don't scare me but this sound just doesn't seem healthy. Also it doesn't go above 4000 (which may just be a carb issue but I'm suspecting it may be a valve spring problem)

One last thing. The previous owner stated that this used to be a cop bike in Illinois and there is all sorts of crazy wire splices. Is there any community knowledge of this?

Thanks.
 

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Did you set the valves at TDC on the intake stroke? Did the valves seem very tight before adjusting?
 

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Yes. Followed all instructions per manual as best we could. Valves didn't seem tight. Previous owner said he had them adjusted "all the way out" which is why I checked. Thinking I need to go back and redo it now the carb is running better.
 

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That is really loud!!! More research needed, and I hope it isn’t anything more than a loose valve adjuster.

‘Hey, there’s always the key’ funny.
 

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Yes. Followed all instructions per manual as best we could. Valves didn't seem tight. Previous owner said he had them adjusted "all the way out" which is why I checked. Thinking I need to go back and redo it now the carb is running better.
The manual isn't very clear on how to determine that you have the engine at top dead center on the intake stroke. Setting the valves at top dead center on the exhaust stroke will result in noisy valves.
 

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Discussion Starter #6
Update.
I have followed the guidance of the manual and it still taps. I have the right side good but I took a stethoscope and the left side is defiantly the source of the noise. Right side I can hear the cam chain going along with the valves but the right sounds like there are gnomes in there with hammers whackin away on the upper part of the valves.
Noise is louder the closer I am to the valves and the left exhaust smokes a little and I think I a touch of burnt oil. I will try again to get the left side clearances double checked but if that doesn't solve it what is my next move?
 

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Discussion Starter #7
After dootling about. I still have no idea. But I got this!
I Donno.
Please pardon my curing and my mess.
Looks like my tap has something to do with my intake valve. I have not attempted to adjust them cause they were still hot.
Was no play in pushrods.
Will wait for it to cool off before I recheck my valve clearances but I have a feeling that isn't it.
Thoughts?
 

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And make sure you are adjusting the valves at TDC on the COMPRESSION stroke, not the Exhaust stroke.
The camshaft rotates at half the rate that the crankshaft does so it is at TDC C (valves closed) on one crank rotation and TDC E (valves open) on the nest crank rotation.
The way to tell which you are on is to set it to TDC, feel for movement in the rockers, rotate the engine 360 degrees until it reaches TDC again and feel for movement again.
When the valves are open the rockers will be pushing against them so the rockers won't move but when the valves are closed you should be able to make the rockers move a bit by hand. If the rockers are tight at one TDC and not the other the tight one is TDC E. If they are loose at both it means you adjusted them at TDC E instead of TDC C so pick the one that feels loosest, adjust the valves at that one and rotate the engine to the next TDC and check that the rockers are now tight.

Re engine temperature: In an ideal world no clearance would be needed and the rocker would touch the valve stem when the valve was closed but not push it open. In the real world the parts of the valvetrain expand slightly when they are at operating temperature so the system needs to have clearance when the engine is cold so that the valve can close fully when hot. Because of that the engine MUST be fully cooled (not touched for at least 4 hours) before adjusting the clearances.
 
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