Left Cylinder !!!

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Roger Ackery
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Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Left Cylinder !!!

Post by Roger Ackery »

Hi, what is causing the left cylinder to have such a wet oily exhaust :?:that bad that it drops an watery oil mess to the ground whist parked on the side stand, Engine rebuilt,
Bike has done 64,000km

Bike running as it should, not smoking much, except under load up long hills,& when motor is cold, initial start up.
Changed gear box oil awhile ago & was short with what came out maybe by 300cc or so. Can a bad check valve in the oil line be the problem, allowing oil to enter the crankcase when the bike is not running :?:
Any ideas on this problem :?: :?: :idea:
Cheers,
Roger
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Cheers.
Roger
GT750A.
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canaletto5
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Joined: Tue Jul 23, 2013 8:43 pm
Location: Derbyshire

Re: Left Cylinder !!!

Post by canaletto5 »

Rog

The oil delivered by the pump is from the cci oil tank and is nothing to do with the gearbox oil. Kev
Roger Ackery
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Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: Left Cylinder !!!

Post by Roger Ackery »

Yes Kev, I know that mate, is it possible to have a ''BAD'' crank seal on the left side & be burning gear oil :?: as I said the oil I drained out of the gearbox appeared to be about 300cc short of the 2,200cc measurement, I ALWAYS MEASURE THE GEAR OIL IN & OUT, to make sure the seals are ok. I also marked the oil tank level,& oil consumption appears to be normal for the kilometres ridden :idea: :!: :!: If this oil mess contains water, could it just be condensation forming in the pipe, :?: :?: the other 3 baffles are slightly damp as you'd expect.. but not dropping oily black liquid onto the ground when on the side stand. The radiator water level hasn't dropped, as I was thinking that maybe it had a failing head gasket :idea:
The bike has now done 400 kilometres since changing the gearbox oil, I was thinking of changing it again at 1,000km, just to see how much comes out to confirm my suspicions about bad crank seals :roll: Nothing appears to be happening on the right hand side with the crankcase breather & oil appearing there ;)
Cheers.
Roger
GT750A.
teazer
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Location: Chicago

Re: Left Cylinder !!!

Post by teazer »

Yes, if gearbox oil level drops it could very well be getting past crank seals. But, the left side is least likely to have that issue. Center and right sit either side of the drive gear and are exposed to transmission oil so those are easy to understand. There is no way for trans oil to get from the drive gear to the left cylinder, so that means it must be going through the outer left gear - if the trans oil is indeed being consumed.

When the engine was rebuilt, how did the ends of the crank look? It is normal to have a slight groove work in the crank where the seals run and on outer ends, there is normally some corrosion where moisture sat at the seal and ate small holes/pits. It is normal to see that on the alternator end and less common on the starter end.
I suppose you could remove the left cover and apply pressure through the left spark plug hole and see if there's any air bubbling out of that seal. You may have to block off a carb and or exhaust to do that which would be a PIA.

Stepping back form that possibility for a moment, how sure are you that all check valves are sealing perfectly, all the time? It doesn't take much of a weep through a check valve to produce an incredible oil mess in a pipe.
Roger Ackery
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Location: Sydney NSW Australia

Re: Left Cylinder !!!

Post by Roger Ackery »

Thanks Teaser,I was thinking more likely to be a check valve,even though 2 stroke oil consumption seems normal,I have got a lot of sludge from the back of the pipe after removing the baffle :evil:
Thanks again
I do have a nos Spider I could fit, but will take SRIS Valve out first & inspect ☹️
Cheers.
Roger
GT750A.
johnbno1
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Re: Left Cylinder !!!

Post by johnbno1 »

just smell the oil if your not sure it will rule out crank seals if they are gone it will stink of petrol and the back pressure can fill the oil pump housing with oil too so pull the cover off hopefully it wont be that
Roger Ackery
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Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: Left Cylinder !!!

Post by Roger Ackery »

;) Thanks John,there is always a little (Blue Oil)
In the pump housing which I've put down to a slight weep from the pump its self ?
I'm not at home to have a good look OR smell for petrol :idea: but will look at it ;)
I have 3 new SRIS valves that I'll fit & see how things go there,bike is running well,no strange noises or rattles,I'm surprised that it's not fouling the plug on that left cylinder ! All 3 spark plugs are a similar colour brownish/tan.
A friend suggested dropping the gear oil again & measuring what comes out,now that the bike has done 500km or so,since the last oil change ?
A brief history..the bike does a very short trip everyday,20 kilometres return to my place,
Spends allday on the side stand,with a piece of wood under it to support it,because of slopey ground,at night at home it's up on the centre stand.
A torch shown down left cylinder spark plug hole shows a slightly wet piston crown,the right hand cylinder is similar,but less :!: I'll pull the SRIS valves out when I get the chance.
Cheers,
Roger
Cheers.
Roger
GT750A.
Roger Ackery
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Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: Left Cylinder !!!

Post by Roger Ackery »

Hi,I have been alerted to check the fuel tap for leaking,also the float height on the left cylinder.
I've noticed in the past a petrol stain on the polished crankcase cover directly under the tap :!:
Cheers.
Roger
GT750A.
Roger Ackery
Posts: 3693
Joined: Wed Jul 20, 2011 3:40 am
Location: Sydney NSW Australia

Re: Left Cylinder !!!

Post by Roger Ackery »

Still a mystery,fuel tap good ? 2 stroke oil pooling in pump housing !?
Cheers.
Roger
GT750A.
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: Left Cylinder !!!

Post by Alan H »

When you find out, let me know. Mine's similar. I now park on the centre stand in tbe garage and it's a bit better, but the right spanny end is moist, centre a bit less and left dry but slightly leaks if left on the side stand!
All 3 smoke. I put it down to the vagaries of 1970s technolology.
Proof that four strokes are over complicated
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