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Discussion Starter · #1 ·
Recently after some work which included an oil change, I have noticed a "hammering" noise at a certain RPM. It starts at about 52-55 MPH in 5th gear, and I can decelerate or accelerate past those points and it will go away. The engine idles smooth with no abnormal noise. The unwanted noise can be heard by easing the throttle to the point of noise while sitting still. There wasn't excessive brass particles in the old oil when changed. It is more like a vibrating noise of sorts that I've never experienced before. Any suggestions?



1981 GL500, 19,233 miles.
 

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Try to post a video. I know the audio isn't always that great but its worth a shot.



Does it happen when hot, cold, or both?
i dont think Phil means to try and get a video of the noise,traveling at 50mph,but can you get the noise to appear on the center stand at a certain revs.

 

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Big ends.

Thats my first thought, hopefully a wrong one but

thats what comes to mind



When they start to go they are usually quiet at idle but as soon as

you put the motor to work they start to hammer.

When they really get shagged they hammer all the time

theres a vid here somewhere of a 650 with bad and I mean bad! end failure.



There was a lad here in Bristol who had his bike nicked and when it was

found I help him get it home in my van

At first it seemed it was OK and after we got it running again it sounded fine

at idle, but as soon as we revved it over 3 thou the hammering started

Bloody shame as he had done a lot of work on it.



I suppose it depends on what you mean by 'hammering' of course, so a vid may help

A loud tapping or clattering may be cam chain, cam shaft,

fan or something loose that vibrates more at certain frequencies.
 

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Discussion Starter · #6 ·
Sorry. I completely misread your post. Yea, on the center stand.



..............long night.


I'll have some time in a day or so to get a good video and post it. I have a feeling and a hope it is minor; maybe camshaft chain slap. I imagine as possible 4th owner it has never or not recently been adjusted. Incidentally, the hammer noise has a "vibration-rattle" associated with it. I was an automotive mech once in my life, but don't recall ever hearing anything like it..... thanks for all the responses so far.



I only hear it at normal operating temperature, because I never run a cold engine at higher than just above idle rpm (1200 max).
 

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I'll have some time in a day or so to get a good video and post it. I have a feeling and a hope it is minor; maybe camshaft chain slap. I imagine as possible 4th owner it has never or not recently been adjusted. Incidentally, the hammer noise has a "vibration-rattle" associated with it. I was an automotive mech once in my life, but don't recall ever hearing anything like it..... thanks for all the responses so far.



I only hear it at normal operating temperature, because I never run a cold engine at higher than just above idle rpm (1200 max).
why not spend an hour,and adjust the chain...prior to making the video.




valves and cam chain adjustment

http://www.pdsrecording.site90.com/cxgl500/CXGLTappets.htm#CXGLTappets
 

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Discussion Starter · #8 ·
Recently after some work which included an oil change, I have noticed a "hammering" noise at a certain RPM. It starts at about 52-55 MPH in 5th gear, and I can decelerate or accelerate past those points and it will go away. The engine idles smooth with no abnormal noise. The unwanted noise can be heard by easing the throttle to the point of noise while sitting still. There wasn't excessive brass particles in the old oil when changed. It is more like a vibrating noise of sorts that I've never experienced before. Any suggestions?



1981 GL500, 19,233 miles.
Since this post, I repaired an oil leak coming from the front engine/trans cover gasket. While doing this I replaced the tach cable, tach drive gasket and seal, and adjusted a very slack oil pump chain. The old tach cable and housing was broken leaving about 4 inches turning and flopping around. Since this repair, the noise is gone. Guess the noise was coming from something that was repaired, probably the cable. Thanks for all the replies!

-Carl
 

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Since this post, I repaired an oil leak coming from the front engine/trans cover gasket. While doing this I replaced the tach cable, tach drive gasket and seal, and adjusted a very slack oil pump chain. The old tach cable and housing was broken leaving about 4 inches turning and flopping around. Since this repair, the noise is gone. Guess the noise was coming from something that was repaired, probably the cable. Thanks for all the replies!

-Carl
sweet,a happy ending
 

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Glad it is fixed I was thinking an exhaust leak...

Glad I was wrong!
 

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Hey man, is the hammering pre-ignition? The fuel we have in the U.S. is like dog piss and will require a higher octane. Remember the 500 has a 10:1 compression ratio. Don't use methonal mixed fuels and research what additives the refiners are putting in their fuels. In

colorado, the refinery in Denver has a summer blend, and a winter blend. All of it a witches brew. Pre-ignition comes in under load and heavy throttle in the "lugging" range. Just some food for thought.
 

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Hey man, is the hammering pre-ignition? The fuel we have in the U.S. is like dog piss and will require a higher octane. Remember the 500 has a 10:1 compression ratio. Don't use methonal mixed fuels and research what additives the refiners are putting in their fuels. In

colorado, the refinery in Denver has a summer blend, and a winter blend. All of it a witches brew. Pre-ignition comes in under load and heavy throttle in the "lugging" range. Just some food for thought.


Dino....you should really read the posts in a thread before you reply....his problem was solved several hours before you posted.....come on man.
 

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Since this post, I repaired an oil leak coming from the front engine/trans cover gasket. While doing this I replaced the tach cable, tach drive gasket and seal, and adjusted a very slack oil pump chain. The old tach cable and housing was broken leaving about 4 inches turning and flopping around. Since this repair, the noise is gone. Guess the noise was coming from something that was repaired, probably the cable. Thanks for all the replies!

-Carl




Er - how does one adjust a oil pump chain? Do you have to take off the front cover?
 

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Er - how does one adjust a oil pump chain? Do you have to take off the front cover?


Yes, but the adjustment is very minimal, and probably a bit tricky from what I know of it. I would think replacing it with new would be much wiser. They are not all that expensive. $40 ish, maybe cheaper with some digging.



 
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