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ratling sound '78 gs 750

  • Thread starter Thread starter Anonymous
  • Start date Start date
A

Anonymous

Guest
Hi there,

I have a problem with my '78 gs 750. It has 46000 km on the clock.
When I start the bike, and she's still cold (on shoke) there's no problem.
But when the engine is at operating temperature, it makes a ratling sound at stationairy rev's. (800-1000 rpm) At first I thought it was the cam chain, but when I asked a mechanic he loosened and tightened the cam chain tensioner, and the noise was stil there. He told me that it was very unlikely that the noise came from the cam chain. He told me that he never heard it before, but that he thought it was the big end on the crankshaft.
I know that that's a very big and expensive operation, so before I take apart the block, I'd like to know if anyone had this same problem.
Is this a common problem for these engines?
Or can anyone tell me what also could be the problem?

By the way, sorry for my bad english, I'm not so fammiliar with the technical language.

I'm very interrested in your opinion, so if you have any questions, please ask me, and I'll awser them as fast as I can.

Thank you.

Frank
 
Does it go away when the rpm's are increased? Does it change when the clutch is operated? Sounds more like a problem with the clutch basket. Although most GS engines are noisey by nature
 
My bike has done that the entire 12 years I owned it. This year when rebuilding the bottom end Falicon replaced the one end of the crank shaft. Maybe that was it. If it doesn't do it anymore When I get it back then I would guess yes. I have never worried about it as it has never caused a problem. Then again, these engines are notorious for running with fairly serious problems and seem other than a few sounds and quirks to be OK. This is no excuss to treat them that way though. I would get it looked at by a knowledgable GS mechanic and fixed if needed. I am not going to even neglect my bike anymore.
 
I would look at the cam chain tensioner more closely first.
They are famous for sticking and the spring on the outside relaxes over time. Even if it seems to pass the test procedure in the factory manual, it may not be advancing enough. Make sure the set screw on the left side is 3/8 to 1/2 of a turn out from seated. 1/2 is fine but not more. Make sure the screw does not turn when you re-tighten the holding nut. If that does not help, I would take off the tensioner and inspect.
Hold the tensioner firmly and push the spring loaded rod in all the way while turning the knurled knob w/spring counter-clockwise until it stops.
Hold the rod in and release the knurled knob. Now slowly let the rod come out and watch the knob advance. If the knob stops advancing too soon and the rod is still coming out under spring tension, the spring has weakened. You can pull the knob spring out of it's hole and give it more strength by turning it counter-clockwise 1 full turn and re-install.
If this does not help, you may still have internal problems with the tensioner or a bad cam chain.
Without hearing the sound myself, this is what I would try.
 
Re: ratling sound '78 gs 750

My 79 GS 750E has done that same thing every since I have had it which is about 35000 miles. On mine, it is the clutch basket that is rattling. It has not become any louder in the two years I have had it and it doesnt have any effect on the clutch operating, so I have not done anything about it. It is loud enough that if you didnt know what it was, you would be worried. :-) :-)

Earl



Frank said:
Hi there,

I have a problem with my '78 gs 750. It has 46000 km on the clock.
When I start the bike, and she's still cold (on shoke) there's no problem.
But when the engine is at operating temperature, it makes a ratling sound at stationairy rev's. (800-1000 rpm) At first I thought it was the cam chain, but when I asked a mechanic he loosened and tightened the cam chain tensioner, and the noise was stil there. He told me that it was very unlikely that the noise came from the cam chain. He told me that he never heard it before, but that he thought it was the big end on the crankshaft.
I know that that's a very big and expensive operation, so before I take apart the block, I'd like to know if anyone had this same problem.
Is this a common problem for these engines?
Or can anyone tell me what also could be the problem?

By the way, sorry for my bad english, I'm not so fammiliar with the technical language.

I'm very interrested in your opinion, so if you have any questions, please ask me, and I'll awser them as fast as I can.

Thank you.

Frank
Click to expand...
 
My '83 750E has the same clutch rattle at idle until fully warmed up (which can take quite some time, the cold-hearted wench!!).



-Q!
 
I had the rattle on my 83 GS750, sounded like the tranny was going to explode. I got the answer here, clutch basket hub nut, it had loosened, even though there is a tab lock washer. Torqued the nut, problem solved.
I almost didn't buy the bike the rattle was so loud.
 
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