82 GS850 vacum leak

[Anonymous]

New guy to the GS forum - I am looking at purchasing a 83 GS850GL the owner says that it has a vacum leak in the head gasket. He said that when he sprays carb cleaner around the head gasket that the bike reves up. he said that the bike was cutting out on him and wouldnt rev up. I can not test it as he currently has the carbs in a box. Is it more likely that it is in the carb boots and that they need to be replaced with new boots and O rings or could it actually be the head gasket needs to be replaced. If it is the head gasket could it just be that the head bolts need re-torked or is this a common issue with this model bike? I have restored a honda 1975 CB500 and 1977 CB550 so I am pretty familar with what to look for in a used bike of this age anything inparticular on the 82 GS850 GL that I should be aware of?

Thanks Bart

[Guy]

Sounds more like the carb inlet rubbers/o-rings. They perish and crack with age and cause the symptoms you describe.

[bwringer]

Yup, sounds more like the intake o-rings.

http://bwringer.com/gs/intakeorings.html

http://cycleorings.com/intake.html

A head gasket that was leaking that badly would also be spewing oil like mad and blowing out combustion mixture. The head gasket has to seal the moderate pressure in the oil passages and the extreme pressure of compression and combustion. So basically, you'd see a lot more obvious evidence of stuff leaking out than air getting sucked in.

Hopefully, the bike hasn't been run long like that -- believe me, it's a great way to burn up the inner two exhaust valves. Ugly. Very ugly.

Pesonally, I would definitely do a compression check to make sure the valves aren't burned. Squirt some oil in through the spark plug hole to create a bit of a temporary seal for the rings and to make sure you're testing the valves.

[Anonymous]

Thanks for the good info. I have been meaning to get a compresion test tool anyway. The current owner picked it up as a project bike and has lost interest in it so not sure how long it had been run like this as the current owner took the carbs off and then lost interest in it. The top front around where the tack comes out of the engine has some grime on it along the gasket. Not sure if the front of the engine had a lot of road grimy and when he cleaned it it just did not clean up on the gaskets or if it is leaking in that area. The back of the engine around the carbs looked pretty clean no sign of oil leaks. I will let you know what I do the guy is only asking $250 for the bike. For that price I might just grin and bear the wrath of "You did what! you don't need another motercycle project!!!"
Bart
75 CB500T
77 CB550
2 - 73 CT70

[bwringer]

The tach cable leak is another easy fix:

http://bwringer.com/gs/tachcableseals.html

[Anonymous]

Took some pics of the bike below is a link to them. As you can see the top end has a lot of grime on it. Should I be concerned with this. I was not able to do a compression test as the owner has the battery and carbs out of the bike and I did not see a kick starter on it.

http://charlestonnational.org/GS850/gs850.htm

[Anonymous]

Obviously looking at the pics we couldn't give much of real diagnosis but it looks from those piccies that it is your cam cover gasket and posssibly cam end seals that are leaking, if so it's a really easy fix........however if your going to take the cover off I'd have a look see at otehr stuff like shims etc. it doesn't look like any leaks round the head gasket so you may get lucky on this one.........


BTW Looks like you live near a dust bowl!