Author Topic: Oil in one cylinder, very strange  (Read 713 times)

Offline roadrocket

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Oil in one cylinder, very strange
« on: 23.08. 2017 15:49 »
Hello

I went for quick ride last night, but had to cut it short because of the engine not running well. The right hand cylinder was banging in the pipe, and the bike would be difficult to start. At home I fitted new HT cables.

This afternoon the bike still behaves the same. New plugs and a clean of the slip ring might have helped a little. But still the right hand side pipe smokes a lot. A compression test reveals even compression of 150 psi. The oil tank might have been generously filled, but after draining the sump there is no improvement. When I remove the plug from the right cylinder, smoke oozes out, not so in the left hand side cylinder. So I guess there is oil in the right hand side cylinder, but from where? I would think that if the compression is the same both sides, the rings would have to be fine (or equally bad). The bike has been running great for years, so nothing assembled wrongly.  Can oil collect in the cylinder and then stay there until it is burned, i.e. an overfill that just have to clear itself? The valves are adjusted, and none of them off. The bike starts easily with fresh plugs.

Puzzled!
Otto in Denmark

Offline rocker21

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Re: Oil in one cylinder, very strange
« Reply #1 on: 23.08. 2017 16:16 »
there are only a couple of ways oil can get into the cylinder, either past the rings or down the valve guides, it is possible if the return side of the oil pump is not clearing the sump you may get oil up past the rings, looks like a bit of a strip to find out why.

Online mugwump

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Re: Oil in one cylinder, very strange
« Reply #2 on: 23.08. 2017 19:02 »
comp and scraper rings could be ok giving good compression, but the oil ring may be at fault. Broken or fitted upside down. The oil control ring regardless of condition will not effect the compression figures.

60'Matchy G12
58 AJS 18s
58 Ariel Huntmaster]

Offline roadrocket

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Re: Oil in one cylinder, very strange
« Reply #3 on: 24.08. 2017 12:32 »
Thanks folks. I am now pursuing a different path: the smoking substance might not be oil but petrol. I am suspecting my newly installed tank of being less than clean, and this might have clogged the carburettor, enriching the mixture to a point where it almost can't run. This also explains why everything was fine during the last ride, and then it sits for some days, and then misbehaves. If fine debris assembles near the petcocks being the lowest point, it will then be in prime position to be inhaled in the carb, blocking the gasflow. At least that is what I can concoct myself, but will shortly have a look inside.
Otto in Denmark

Offline roadrocket

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Re: Oil in one cylinder, very strange
« Reply #4 on: 24.08. 2017 20:00 »
Doh! There was nothing wrong with the bike! When I have stopped banging my head to the wall I might reveal the cause of the symptoms.
Otto in Denmark

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Re: Oil in one cylinder, very strange
« Reply #5 on: 24.08. 2017 20:37 »
Doh! There was nothing wrong with the bike!
It's good to hear there was nothing seriously wrong with the BSA.
Quote
When I have stopped banging my head to the wall I might reveal the cause of the symptoms.
Put your helmet on first.

I can't wait for the next thrilling chapter! *smile*

Offline roadrocket

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Re: Oil in one cylinder, very strange
« Reply #6 on: 25.08. 2017 12:16 »
Well, I put said alternative tank on from a B 40 WD, which is essentially the A 10 tank just without recesses for emblems, and to go with it, a set of ace bars. So is now a bit of a café job. These bars don't provide much room for all the controls, so the choke lever was placed pointing strangely forward. This all very well, and it worked fine. But somehow the choke lever was set to full boost, which I didn't take any notice of (even after doing it myself), so trying to run the bike on full choke did nothing for perfomance (well only very adversely...). I now know how this sounds and how the engine behaves.

Yes, yes, I will have a to eat a slice of humble pie now...
Otto in Denmark

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Re: Oil in one cylinder, very strange
« Reply #7 on: 25.08. 2017 15:07 »
 ::hh::

Offline duTch

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Re: Oil in one cylinder, very strange
« Reply #8 on: 25.08. 2017 22:48 »

 So what about the oil in/on the pipe?
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia

Offline BSA_54A10

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Re: Oil in one cylinder, very strange
« Reply #9 on: 26.08. 2017 09:05 »
Well, I put said alternative tank on from a B 40 WD, which is essentially the A 10 tank just without recesses for emblems, and to go with it, a set of ace bars. So is now a bit of a café job. These bars don't provide much room for all the controls, so the choke lever was placed pointing strangely forward. This all very well, and it worked fine. But somehow the choke lever was set to full boost, which I didn't take any notice of (even after doing it myself), so trying to run the bike on full choke did nothing for perfomance (well only very adversely...). I now know how this sounds and how the engine behaves.

Yes, yes, I will have a to eat a slice of humble pie now...

The WD B40 tank is a Gold Star tank.
When that was worked out some years back all the B40 tanks rapidly vanished.
Being that they were all painted, it was a easy job to strip the paint then chrome the tank and flog them off for 6 times the price.
Bike Beesa
Trevor

Offline roadrocket

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Re: Oil in one cylinder, very strange
« Reply #10 on: 26.08. 2017 20:59 »
I paid 50 pounds worth of Danish dosh for mine a couple of years ago. Not a dent and solid without sealer. It is now New Brunswick Green.
Otto in Denmark

Offline trevinoz

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Re: Oil in one cylinder, very strange
« Reply #11 on: 27.08. 2017 03:31 »
The WDB40 tank is not a Goldstar tank and needs quite a bit of work to become one.