please help. first project bike gs750 1978 leaking oil from exhaust and intake

[falco]

Hi I'm new to the forums and have been doing a good deal of reading on here but can't find an answer.


my gs750 leaks oil from the far left exhaust manifold (small steady drip) can't figure out why, i took it for a ride today and after about 2 miles i looked down and it started spraying oil everywhere, out the exhaust and the carburetor(still far left side)
oil may have been leaking from other places but it was hard to tell as i pulled over the bike.

as the bike warmed up the oil leaked more and the throttle hesitated more and more until it died. felt like a it was losing compression.



please help! thanks

 

[JamesWhut?]

Oil from the Carb?

Look at the underside of the motor and the side covers for leaks. Sometimes an oil leak that looks like its coming 'from" an exhaust header, is actually coming from somewhere else and just dripping and flowing back along it.

Pull the #1 plug. is it oil or black gunk covered? blown valve guide seal.

 

[falco]

Oil from the Carb?

Look at the underside of the motor and the side covers for leaks. Sometimes an oil leak that looks like its coming 'from" an exhaust header, is actually coming from somewhere else and just dripping and flowing back along it.

Pull the #1 plug. is it oil or black gunk covered? blown valve guide seal.

I just replaced all the plugs today, black gunk covered for sure.

 

[JamesWhut?]

Needs a top end rebuild.

 

[chuck hahn]

Check the oil. take cap off and smell for gassy odor. If the petcock failed it will fill the crankcase with gas and then the lubrication for the engine is gone. Dont even start it till you are 1000% sure it isnt full of gas. Drain the oil and start over with fresh is what I would do. If more than 3 1/2 QTs comes out when you drain the oil there is your problem.

An over full crankcase forces the oil / gas slop to go somewhere and usually it either out the exhaust or thru the breather cover and runs down into the airbox from the breather tube. Im leaning at a petcock failure as my first suspect...especially if it wasnt that way before and suddenly it has happened.

 

[allojohn]

Check the oil. take cap off and smell for gassy odor. If the petcock failed it will fill the crankcase with gas and then the lubrication for the engine is gone. Dont even start it till you are 1000% sure it isnt full of gas. Drain the oil and start over with fresh is what I would do. If more than 3 1/2 QTs comes out when you drain the oil there is your problem.

An over full crankcase forces the oil / gas slop to go somewhere and usually it either out the exhaust or thru the breather cover and runs down into the airbox from the breather tube. Im leaning at a petcock failure as my first suspect...especially if it wasnt that way before and suddenly it has happened.

Chuck, these are VM carbs, if the petcock failed wouldn't the gas just flow out the overflow tubes?

 

[Fjbj40]

Probably just the valve cover gasket for the oil leaks.

Get some water based degreaser, spray engine down, let stand for awhile, rinse with water. Allow to dry, start bike, look for leaks at top of engine.

Have you done an oil change yet? If not, as Chuck mentioned, do that before you run it.

Report back the results

 

[chuck hahn]

All my bikes have VMs and when my 78 1000C failed it had almost a gallon of fuel mixed in with the oil. I thought the drain pan was gonna overflow. What clued me off was the fuel gauge actually. I hit the key and the fuel level was oddly way to low from what I remembered from the last ride so I smelled the filler hole. No fuel from the carbs, airbox or under the bike at all. Most likely the fuel ran down the vacuum tube off carb 3.

 

[falco]

Check the oil. take cap off and smell for gassy odor. If the petcock failed it will fill the crankcase with gas and then the lubrication for the engine is gone. Dont even start it till you are 1000% sure it isnt full of gas. Drain the oil and start over with fresh is what I would do. If more than 3 1/2 QTs comes out when you drain the oil there is your problem.

An over full crankcase forces the oil / gas slop to go somewhere and usually it either out the exhaust or thru the breather cover and runs down into the airbox from the breather tube. Im leaning at a petcock failure as my first suspect...especially if it wasnt that way before and suddenly it has happened.

not smelling any gas in the oil.

it WAS happening before just not to this extent, there has always been a small oil drip from from the exhaust manifold. it sprayed oil after taking it for a first ride.

 

[falco]

Probably just the valve cover gasket for the oil leaks. Get some water based degreaser, spray engine down, let stand for awhile, rinse with water. Allow to dry, start bike, look for leaks at top of engine. Have you done an oil change yet? If not, as Chuck mentioned, do that before you run it. Report back the results

already replaced valve cover gasket and changed the oil

 

[tkent02]

Obviously the first step is to clean off the engine so you can se where it's leaking from. Do as Fjbj40 says, and find the leaks. Maybe it's leaking everywhere, maybe one big leak and swirling around. Maybe the whole thing needs to come apart, maybe not. It's hard to tell from here.

 

[falco]

Obviously the first step is to clean off the engine so you can se where it's leaking from. Do as Fjbj40 says, and find the leaks. Maybe it's leaking everywhere, maybe one big leak and swirling around. Maybe the whole thing needs to come apart, maybe not. It's hard to tell from here.

will do! also doing a compression test on the cylinders, will post results

 

[falco]

update:
compression came in at around 115 psi for pretty much every cylinder.

i cleaned off the engine, oil must be coming from the valve cover but leaking somewhere i can't get a view of.

i also forgot to mention that oil shot out of the breather house last time i went for a ride..



thanks for all the replies so far

 

[tkent02]

How full is the oil in the crankcase? Above the window or just right?

 

[falco]

How full is the oil in the crankcase? Above the window or just right?

window seems like its fogged over but looking down into it, oil seems higher than the window.

would that cause high compression and oil to erupt out of the breather hose?

 

[tkent02]

Too much oil can make it come out the breather. You sure it doesn't smell like gasoline?

If not someone overfilled it.

 

[falco]

Too much oil can make it come out the breather. You sure it doesn't smell like gasoline?

If not someone overfilled it.

I'm pretty sure it doesn't have gas in the oil, just in case my nose was fooling me i took a spoonful out and tried lighting it with a lighter to see if anything would burn but nothing.

at a second glance there is too much oil..