Cam wear / low compression could they be related?

[1948man]

Try putting vacuum on the line as the carb does when the engine is running. Maybe it will leak, maybe a PO fixed the petcock, I dunno.
Either way ride it, a lot of miles, it should be fine. Maybe a top end rebuild is in the future (like next winter?) maybe not, but get everything else working correctly and ride it.

Does this mean the bike has to be running when you test this and how do you do it? Do u use some kind of suction device or just suck on it and hope not to get any gas?

[haggisbasher]

It should flow freely on Prime.

My understanding from reading here is that the dreaded 80-82 petcock still requires a vacuum to start the flow even on prime. On a correctly functioning petcock there will be no flow on either setting without some vacuum. In prime the flow will continue after the vacuum is removed while on run it will stop as soon as vacuum is removed. I may be mistaken.

Tom

[1948man]

You know, I have an '83 and assumed they would be the same. You probably know more about the '82's than I do. I don't know why they designed it that way. Hard to drain the tank or send fuel to fill the carbs that way. What do I know?

[haggisbasher]

As I said I may be mistaken, I only have what I have read on this site to go on.

Tom

[1948man]

The downloadable Owner's Manual on Bikecliff's site for an 1100gl shows the fuel flowing in the Prime position without a vacuum. I see dates of 1981 and 1982 in that manual near the end so I guess it would cover a 1982

[haggisbasher]

According to the parts fiche the 1100GL has a different petcock from the 80-82 GS750L. Mine has no lever to operate the valve, you need a screwdriver to turn from run to prime and it has no reserve.

Tom

[Nessism]

According to the parts fiche the 1100GL has a different petcock from the 80-82 GS750L. Mine has no lever to operate the valve, you need a screwdriver to turn from run to prime and it has no reserve.

Tom

The lever less petcock debuted in 1980...and went away the next year on most models. Gas will not flow on Prime until the petcock vacuum line sees a pulse of vacuum. At that point the gas will flow regardless of more vacuum so you need to turn the slot to On after that if you want the fuel to stop flowing.

Petcocks fail in a few different ways including sending fuel down the vacuum line and into the engine via the #2 carb. Those level less petcocks also fail when the check valve inside craps out.

Good thing is they are fairly cheap petcocks so if you have any questions I suggest getting a new one.

[rapidray]

I suggest you button that bike back up and ride.

Ed, I can't believe you told him this!!! Go ahead & keep running it while the exhaust cam & rockers continue to eat themselves & send MORE crap through the engine?!!! What are you thinking? Ray.

[Nessism]

Ed, I can't believe you told him this!!! Go ahead & keep running it while the exhaust cam & rockers continue to eat themselves & send MORE crap through the engine?!!! What are you thinking? Ray.

I've seen worse ray. I think the photo makes it look worse than it is.

[haggisbasher]

Hey guys

Is it possible that the cams arent really damaged that badly but the rocker bearing material is smeared across the cam lobes for want of a better description. When it warms up again I will pop the cover and try and take some better pics. It looked to me more like material was deposited on the lobes rather than the lobes were worn through.

It would make sense to me that the rocker was designed to be softer than the cam so that the cheaper component wears first. I have no real mechanical experience so I'm just throwing that out there.

Thanks all
Tom