Gs 750 cam shaft trouble

[jayzer81]

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

[tkent02]

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?

[BassCliff]

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

[Nessism]

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.

[tkent02]

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.

I'm guessing it's a lubrication related problem.

[Nessism]

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.

I'm guessing it's a lubrication related problem.

I'm guessing it has nothing to do with the cams, other than maybe the valve adjustment has been neglected

[tkent02]

I'm guessing it has nothing to do with the cams, other than maybe the valve adjustment have been neglected

Oil neglection may be a problem as well.

[BassCliff]

Hi,

Mr. jayzer81 has more of his story scattered about...

http://www.thegsresources.com/_forum/showthread.php?t=186198

http://www.thegsresources.com/_forum/showthread.php?t=186236

http://www.thegsresources.com/_forum/showthread.php?t=186237

http://www.thegsresources.com/_forum/showthread.php?t=186238

As you can see, the same issue cross-posted in four different sections but no details regarding regular maintenance procedures.

Thank you for your indulgence,

BassCliff

[tkent02]

As you can see, the same issue cross-posted in four different sections but no details regarding regular maintenance procedures.

Running it until it drops isn't considered a regular maintenance procedure?

[jayzer81]

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

[tkent02]

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

What were the results of your dry compression test?

[Nessism]

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.

[tkent02]

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.

Ed, apparently everything ran fine before being run out of oil.
That won't change the jetting much.

[bwringer]

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.

[tkent02]

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.

He ran it with no oil in the engine.