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Author Topic: CB750 Engine Howl  (Read 946 times)

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Offline turkey4me

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CB750 Engine Howl
« on: October 25, 2011, 08:27:18 PM »
Please take a listen to this you tube video clip.  After about 20 seconds I pull the clutch and you can hear a fairly loud howl that I think is coming from the primary gear drive.  Is this normal for a 76 CB 750F?  Has me somewhat concerned.

CB Engine

<iframe width="425" height="349" src=" frameborder="0" allowfullscreen></iframe>
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Offline CycleRanger

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Re: CB750 Engine Howl
« Reply #1 on: October 25, 2011, 08:30:30 PM »
egads! :o

Have you found anything unusual in the oil pan yet?
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Offline wrenchmuch

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Re: CB750 Engine Howl
« Reply #2 on: October 25, 2011, 08:41:28 PM »
Does it make the sound if you get it into neutral after pulling the clutch in? Can't tell direction of sound from a video clip . Do you think its coming from inside the engine ? If its internal I bet its coming from the transmission . Check the sump like CR suggested .
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Offline turkey4me

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Re: CB750 Engine Howl
« Reply #3 on: October 25, 2011, 08:51:05 PM »
I'll check the sump and noise with gear in neutral.  I don't hear much below 30 mph.  In the video I am doing about 50 when I pull the clutch.  Noise is definitely coming from the left side of motor
« Last Edit: October 25, 2011, 08:55:57 PM by turkey4me »
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Offline cben750f0

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Re: CB750 Engine Howl
« Reply #4 on: October 25, 2011, 09:13:52 PM »
whats your chain and sprockets like, and badly worn chain will howl when it runs dry of lube... just a thought.

peace
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you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/

Offline ofreen

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Re: CB750 Engine Howl
« Reply #5 on: October 25, 2011, 10:05:00 PM »
Quote from: cben750f1 on October 25, 2011, 09:13:52 PM
whats your chain and sprockets like, and badly worn chain will howl when it runs dry of lube... just a thought.

peace

Yes, especially at the countersprocket.
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Greg
'75 CB750F

"I would rather have questions I cannot answer than answers I cannot question." - Dr. Wei-Hock Soon

Offline cben750f0

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Re: CB750 Engine Howl
« Reply #6 on: October 25, 2011, 10:11:31 PM »
exactly, when he said from the LH side, that got me thinking...thanx for the back up=)


peace
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you are never to old, to act like a kid... be safe
funny thing,chasing someone down hill on a bike 30 years older than theirs..
he said \\\\\\\'it was like watching a 250kg unguided weapon getting stuck up you bum\\\\\\\ http://www.bikepics.com/members/trixtrem/

Offline KRONUS0100

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Re: CB750 Engine Howl
« Reply #7 on: October 26, 2011, 07:21:01 AM »
wierd.  almost sounds like when you try to stop a bicycle tire from spinning with your shoe when it first starts.  tire rub?  chain and sprockets?  on mine there is a piece of rubber  like material on the lug inside the front sprocket cover.  could yours be loose?
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current bikes:  1976 CB750F, 1981 GS1100E
bikes owned:1981 GL1100I, 1990 GS500E, 1981 GS850, 1977 and 1979 GS750, 1974 CB750, 1975 CB750, and a 1982 GS750E
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