Author Topic: Noise(clack,clack,clack) coming from engine with clutch in, at a walking pace  (Read 2052 times)

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Offline Thunder

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Hi guys

well my first post, and i just wanted to say how thankful i am that you guys are out there... ;D

Well, after much scouring of the second hand (fifth hand more likely)adverts i bought a non runner. ???

1978 cb750 SOHC ss F? As near as i can tell...



Took her home, and she was as the owner had stated, an electrical mess having been standing for three years, outside.
First things first, oil change, then on to the elec-trickery. And , lo and behold after ea new battery, all contacts cleaned, she fired and ran after bout ten turns of the engine. ;D ;D, and she sounded sweet, no major knocks or anything.Wow( i thought0

Cleaned the carbs,half got the brakes working(wip i assure you),chain off and on again after lubing and it was time to test ride.

She didn't want to go :-\, but after some fiddling with the adjustment bolt by the clutch housing where the lever arm fits onto, she went. ::)

Now the problem i'm having (and i've done a search on the forum, i'm just not sure what i'm looking for.). She pulls cleanly, and the motor sound sweet(cam chain needs adjustment), but when i coast(clutch in) to a stop i get a serious clack,clack,clack, located where the front sprocket sits.The noise is reminiscent of a tight chain over a worn sprocket where it doesn't disengage properly and clacks off each worn tooth), and it's serious enough to feel through the bars.

When i coast in neutral it doesn't make this noise (eliminating the chain i think). Does anyone have any idea what could be the cause?

thanks for any and all help.
Cheers
Thor
« Last Edit: November 09, 2008, 12:08:54 PM by Thunder »

Offline 78 k550

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Re: Hi, my first post and i need help already
« Reply #1 on: November 08, 2008, 07:48:55 AM »
if you didn't change the chain it might of got stiff sitting in one spot around the smaller sprocket. I would swap out chain with new one regaurdless.

Paul
Paul
Littleton, CO

76/77 CB 750F, 
75 GL1000, (AKA GL1-242 NGWClub),
76 GL1000 LTD
84 GL1200 Standard
6 Bultaco's= 42, 49, 121, 152, 167, 188

Offline Thunder

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Re: Hi, my first post and i need help already
« Reply #2 on: November 08, 2008, 07:55:21 AM »
Yip, i know what you mean , thanks ;D,but i did check the chain and when coasting in neutral , with no force on the chain , its smooth.

Offline WFO

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Re: Hi, my first post and i need help already
« Reply #3 on: November 08, 2008, 09:11:16 AM »
When i got my bike it hadn't been ran in quite awhile and when i adjusted the cahin and lubed it up it made that exact sound you are discribing, it was a stiff couple links but the sound did go away after a 100 miles of riding but iam going to change out the sprockets and chain this winter anyways. (But i think you have a stiff chain) you also say the sound went away when coasting in neutral i think when you are applying the brake it adds some tension on the chain thus making the sound and exposing those stiff links and coasting in neutral adds no tension ( hope that makes sense) but i would change out the chain and sprockets if it's been setting outside that long.
« Last Edit: November 08, 2008, 09:16:50 AM by WFO »
82 cb650 sc nighthawk - 78 kz 650 b

Offline Hush

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Re: Hi, my first post and i need help already
« Reply #4 on: November 08, 2008, 11:29:07 AM »
When I finally rode my rebuilt 650 I had this horrendous knock from the front sprocket, turned out to be the internal chain guide which I had cleverly straightened right into the path of the rotating chain.
Didn't make that noise when testing in the garage, had to ride it to find out.
I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline Thunder

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Re: Hi, my first post and i need help already
« Reply #5 on: November 09, 2008, 12:07:28 PM »
Well thanks for the advice guys ;D, well i rode her again today(not far ,down the road and back) whilst checking out the front sprocket movement (looking for a siezed chain), and it seems clear.A buddy mentioned that it sounds like my clutch hub is loose??? is this possible??

he problem occurs when slowing down to walking pace and pulling the clutch in i get a clunk,clunk,clunk, from below.

I really am at my wits end(short of engine removal), anything else i can try?

Offline Hush

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Put bike on the main stand but don't start it, spin the back wheel by hand in neutral, this will tell you if it is the chain or not.
Next start the bike (still on the main stand) and shift into 2nd or third at low speed, does the noise appear now?
If the noise is still there, engage the clutch, what sort of noise do you get now?
When tracking down the "odd" noise it's a matter of experimentation unless something is glaringly obvious.
Spinning the wheel without the motor running helps as you are not competing with the engine noise as a distraction.
Also while up on the stand you may as well adjust your drive chain, slop in the chain can be noisey too as can too tight a chain.
I think the thing I most like about motorcycling is the speed at which my brain must process information at to avoid the numb skulls who are eating pies, playing the ukulele, applying make-up etc in the comfort of their airconditioned armchairs as they make random attempts to kill me!!!!!!!

Offline Thunder

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cheers, sound like a good plan,will look into it and let you guys know.Thanks again

Offline Tower

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What's a clutch hub?

Depending on the kind of chain you have, it might be obvious there's a sticking link, missing o-ring, missing roller sheath, etc.  Look to the sprockets for confirmation of excess wear - one or a few teeth will appear pointed, scalloped, pointed or worn. 

Since nothing in your problem description matches the symptoms of worn or misadjusted clutch, I'd replace the chain before making my way to the clutch.

Offline KRONUS0100

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I had a bad experience witha 90 GS500E.......pull that front sprocket off the shaft....check and make sure that the splines are not worn.....I was thrown off the bike when it suddenly siezed and locked the back tire....spline wear causes the sprocket to walk and wobble at low speeds and downshifting....mine was not noticed (missed by 3 people) until the shakedown run.
MATT
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