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Dear all, I could use some help diagnosing the oil consumption on my GS1000 '78 — and discuss the possible remedies & their respective consequences.
well: the engine uses oil. Between 2 to 4 liters per 1000km (0.5 to 1 gallon every 650 miles) depending on driving style. Highway driving (+130kph / +80 mph) uses a lot of oil!
- the bike drives well, has good power, consumes about 7L/100km (33.5 mpg)
- Last winter I changed the valve seals, they should be good.
- valve clearance was checked last winter, before changing valves seals and clearances were good. Didn't recheck after changing valve seals.
- valves + pistons had carbon buildup (hard, crystal like, black residue)
- Compression, warm, throttle full open is close to 10.5 bar (145 psi). I don't trust the testers values too much, but the values are consistent. (might as well be 9 bar). Adding some oil to the cylinder and the values go up slightly to about 11 - 11.5 bar (160 psi).
- I mostly drive in low rpms (3000-5000rpm), occasionally go to 7000rpm, never hit redline at 8500. It's an old lady. That said, I tried some italian tune-up lately; hard accelerating and engine braking in low gears, reaching close to red-line occasionally.
- Tried full synthetic engine oil recently, which def did good on the gears. Engine subjectively ran smoother but oil consumption stayed the same.
- Engine spills some oil from base gasket (between crankcase and cylinder block) at the front of the engine, right side. It's noticeable, the oil finds its was around the fans when driving, but it can't possibly explain all of the oil consumption. When taking the head off, the gaskets were a joke. Possibly the base gasket is f*cked as well.
- Sometimes, friends mention some smoke coming from the exhaust. Not consistent though.
- Poked a little camera through the plugs opening and the cylinders look good enough.
- Don't know whether there's oversized pistons in there.
I took over the bike about 4 years ago.
The only thing that comes to my mind now is that the piston rings are shot. That's a hell lot of work to repair them.
Could it still be something else?
Anything to do or test before taking the whole engine apart?
Could the rings just be stuck? How to get them loose?
Are rings still commonly available for all of the piston sizes?
Looking forward to your feedback!
well: the engine uses oil. Between 2 to 4 liters per 1000km (0.5 to 1 gallon every 650 miles) depending on driving style. Highway driving (+130kph / +80 mph) uses a lot of oil!
- the bike drives well, has good power, consumes about 7L/100km (33.5 mpg)
- Last winter I changed the valve seals, they should be good.
- valve clearance was checked last winter, before changing valves seals and clearances were good. Didn't recheck after changing valve seals.
- valves + pistons had carbon buildup (hard, crystal like, black residue)
- Compression, warm, throttle full open is close to 10.5 bar (145 psi). I don't trust the testers values too much, but the values are consistent. (might as well be 9 bar). Adding some oil to the cylinder and the values go up slightly to about 11 - 11.5 bar (160 psi).
- I mostly drive in low rpms (3000-5000rpm), occasionally go to 7000rpm, never hit redline at 8500. It's an old lady. That said, I tried some italian tune-up lately; hard accelerating and engine braking in low gears, reaching close to red-line occasionally.
- Tried full synthetic engine oil recently, which def did good on the gears. Engine subjectively ran smoother but oil consumption stayed the same.
- Engine spills some oil from base gasket (between crankcase and cylinder block) at the front of the engine, right side. It's noticeable, the oil finds its was around the fans when driving, but it can't possibly explain all of the oil consumption. When taking the head off, the gaskets were a joke. Possibly the base gasket is f*cked as well.
- Sometimes, friends mention some smoke coming from the exhaust. Not consistent though.
- Poked a little camera through the plugs opening and the cylinders look good enough.
- Don't know whether there's oversized pistons in there.
I took over the bike about 4 years ago.
The only thing that comes to my mind now is that the piston rings are shot. That's a hell lot of work to repair them.
Could it still be something else?
Anything to do or test before taking the whole engine apart?
Could the rings just be stuck? How to get them loose?
Are rings still commonly available for all of the piston sizes?
Looking forward to your feedback!
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