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1979 Honda CX500 custom
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Hey guys, I've been lurking for a while trying to troubleshoot my bike, and just want some reassurances. I've adjusted the cam chain, looked at the fan, and listed around with a screwdriver and haven't noticed anything that is out of the ordinary. This was my grandpa's bike and he kept up with maintenance, but for whatever reason, he decided to ride on this noise for quite some time. I'd love to ask him how long he did that for, but he's long gone and his bike had been sitting since 2013. It was stored as best as it could and it's still in pretty decent shape. It's so close to being road-ready, I've put a lot of work into it. thanks for your help! I'll attach a video of it running


here is the video
 

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1,624 Posts
Sound like valve clatter. You need to adjust the valve tappets under the covers. Pretty easy if you have some feeler gauges. Download the service manual from the Wiki for the procedure. You'll find a link to it in the technical forum.
Dan
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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12,243 Posts
Be sure the each cylinder is at TDC on COMPRESSION when you make the adjustment. Otherwise, they'll get louder,
 

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1983 cx650c
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Valve noise was my first thought also. The valves should be adjusted every 5000 miles or so, I'm not sure what the recommended interval is exactly. A screwdriver works for searching for unusual noises but a mechanics stethoscope is more precise.
 

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1983 cx650c
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If you're not familiar with adjusting valves definitely study the procedure carefully before hand. The feeler gauges will have light resistance when correctly adjusted, test with different size gauges larger and smaller. It's advisable to roll the motor over and re-check after you think they're set. Also be careful removing and replacing the covers, it's easy to damage the gaskets, sealing rubbers on the bolts, and the bolts themselves by over-tightening. If you encounter difficulty just post more questions.
 

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Feeler gauges are good👍
Me i was never comfortable using zippo cig papers for points on non-Cx bikes..lol
 

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1983 cx650c
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1,308 Posts
We used match book cover for gap,, never heard of using a cig paper to determine points opening but not bad idea in a pinch.
 

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the cellophane on cig boxes is exactly 0.001", or it used to be...
 

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2021 Benelli Leoncino Trail - 2021 CSC SG400 - 2017 SSR Buccaneer 250i - Several CX project bikes
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The bass in the clip makes me think it's something more than just valves. However, it sounds loudest in front of the bike. you briefly moved the camera in front of the radiator and it was loudest there. I also hear valves, but the rythmic noise is deeper. It also sounds like the noise is at crank speed, it seems to coincide with the exhaust pulse.

So if that's the case, there are a few things it could be. In order from best news to worst. First, it could be that there are no copper crush gaskets between the headers and the head. Possible but unlikely. Second, the fan could be smacking something. It doesn't sound like that to me though. Unfortunately, a noise with the same frequency as the exhaust pulse could very easily be a crank bearing, rod bearing, or wrist pin.

Charles.
 

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1983 cx650c
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As Charles says it could be deeper in the motor than valves,,, that's why I highly recommend a 15$ stethoscope for analysis of engine noises. Regardless,, if you haven't set the valves they need to be addressed. After that clatter is lessened then other noises will be more evident. Bottom end noises of serious level (bad rod or crank bearings) are only to be addressed by very serious mechanics.
 

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We used match book cover for gap,, never heard of using a cig paper to determine points opening but not bad idea in a pinch.
It comes from the hippies bible, "How to Fix Your Volkswagen for the Complete Idiot." I kept a full weed leaf in there along with some rolling papers. Came in handy more than once. Filing points, sometimes with sandpaper and resetting timing with the paper was a monthly ritual at times of no money.
 

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Cx500 1978 engine probably later
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Enjoyed the discussion - just fixed a rattle from the front on mine - the noise reduced when I pulled the clutch lever - the clutch basket had excessive longitudinal play on the first motion shaft, I had the wrong thrust washer behind it - see if operating the clutch changes the noise.
Good luck.
Ps - defo valve clearance adjustment to do!
 
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