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Gs 750 cam shaft trouble

  • Thread starter Thread starter jayzer81
  • Start date Start date
J

jayzer81

Guest
Anyone have any experience with worn down lobes on the cam shaft for a 1977 GS750

my bike has been struggling to perform and I'm thinking this might be the issue...

Just out of curiosity if this is the issue what's the remedy...?


thanks in advance...


j
 
Measure the cams, replace them if they need it. Simple stuff.

Have you done all the regularly required maintenance?
Adjusted the valves and all the rest of it?
 
Hi,

That engine would have to be seriously abused to cause cam lobe wear. But if so, just replace the cam shafts.

As Mr. tkent02 has eluded to, have you gone through the maintenance lists in your "mega-welcome"?


Thank you for your indulgence,

BassCliff
 
It's virtually impossible to wear out a cam on the GS shim and bucket engines. They are ultra durable. You need to do more homework on what's wrong with your bike and stop guessing.
 
Nessism said:
It's virtually impossible to wear out a cam on the GS shim and bucket engines. They are ultra durable. You need to do more homework on what's wrong with your bike and stop guessing.
Click to expand...

I'm guessing it's a lubrication related problem.
 
Nessism said:
It's virtually impossible to wear out a cam on the GS shim and bucket engines. They are ultra durable. You need to do more homework on what's wrong with your bike and stop guessing.
Click to expand...

tkent02 said:
I'm guessing it's a lubrication related problem.
Click to expand...

I'm guessing it has nothing to do with the cams, other than maybe the valve adjustment has been neglected
 
Last edited:
BassCliff said:
As you can see, the same issue cross-posted in four different sections but no details regarding regular maintenance procedures.
Click to expand...

Running it until it drops isn't considered a regular maintenance procedure?
 
thanks for the help...and sorry for reposting..."i'm new here"...

I'll go through the maintenance list and see if anything comes up but so far I have:

1. replaced the clutch
2. done dry compression test
3. replaced all filters (air, gas, oil)
4. rebuilt the carbs and put back the original jets
5. set the timing and checked the points and condensers.
6. Charged the battery

Going to check out the cam shaft lobes today...the oil window is really full and a buddy of mine mentioned it might be due to gas leaking in...


thanks again...


j
 
jayzer81 said:
thanks for the help...and sorry for reposting..."i'm new here"...

I'll go through the maintenance list and see if anything comes up but so far I have:

1. replaced the clutch
2. done dry compression test
3. replaced all filters (air, gas, oil)
4. rebuilt the carbs and put back the original jets
5. set the timing and checked the points and condensers.
6. Charged the battery

Going to check out the cam shaft lobes today...the oil window is really full and a buddy of mine mentioned it might be due to gas leaking in...


thanks again...


j
Click to expand...

What were the results of your dry compression test?
 
First thing I'd do is adjust the valves. Next is to check the carb jetting. The jet numbers must match those in the OEM Suzuki Factory Service Manual unless you changed the air filter box or the exhaust system. If that is the case, the carbs MUST be rejetted or the bike will not run right.
 
Nessism said:
First thing I'd do is adjust the valves. Next is to check the carb jetting. The jet numbers must match those in the OEM Suzuki Factory Service Manual unless you changed the air filter box or the exhaust system. If that is the case, the carbs MUST be rejetted or the bike will not run right.
Click to expand...

Ed, apparently everything ran fine before being run out of oil.
That won't change the jetting much.
 
There is a spec in the manual for cam lobe height, but that much damage would be instantly obvious to the eye.

One thing that may be confusing the issue is that the LATER model 16-valve GS750 engines (completely different engines) are well-known to have a problem with top-end oiling.

The earlier model 8-valve GS750 engines have no such problem, and in fact it's hard to imagine how anything other than a total blockage or completely failed oil pump could cause an oiling problem in these engines. In that case, the symptoms would be far more severe than a lack of power.

First things first -- while you have the valve cover off, check and adjust the valve clearances.
 
bwringer said:
The earlier model 8-valve GS750 engines have no such problem, and in fact it's hard to imagine how anything other than a total blockage or completely failed oil pump could cause an oiling problem in these engines. In that case, the symptoms would be far more severe than a lack of power.
Click to expand...

He ran it with no oil in the engine.
 
Tom is right; all four posts that Basscliff linked to stated how the guy didn't check his oil levels and ran it dry.
 
What he should be posting is a location and a request for someone who knows how these engines work to help him figure out how much has been damaged.
 
Nessism said:
First thing I'd do is adjust the valves. Next is to check the carb jetting. The jet numbers must match those in the OEM Suzuki Factory Service Manual unless you changed the air filter box or the exhaust system. If that is the case, the carbs MUST be rejetted or the bike will not run right.
Click to expand...

tkent02 said:
Ed, apparently everything ran fine before being run out of oil.
That won't change the jetting much.
Click to expand...

Tom,
We don't know for a fact that the bike was run out of oil. We just know the oil was not checked and then the bike started to run poorly at some point thereafter. Most likely, the oil level is a little low, then when the bike started to run poorly a mistaken assumption was made connecting the two. Just like assuming the camshafts are worn, which is extremely unlikely.
 
Nessism said:
Tom,
We don't know for a fact that the bike was run out of oil. We just know the oil was not checked and then the bike started to run poorly at some point thereafter. Most likely, the oil level is a little low, then when the bike started to run poorly a mistaken assumption was made connecting the two. Just like assuming the camshafts are worn, which is extremely unlikely.
Click to expand...

Well either way, getting answers out of this guy is like pulling teeth. He needs someone to look at it that knows these engines.
Have fun.
 
My Gs1000s had roughly done 95,000miles when I had it stripped and rebored to a 1085.
we found the cams were badly worn, not pitted or blue, but they were well below spec...
one thought we had they had been swapped from another Gs......
 
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