G5 blue smoke and plug oiled.

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vigo
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G5 blue smoke and plug oiled.

Post by vigo »

Recently bought this bike it had lost compression. The headgasket had been in correctly fitted by previous owner. Reassembled with new gasket, starts and runs great,but and a it's a big but, blue smoke and plug and cylinder wet. The bike has a +040 piston and there seems no further cylinder wear. What seems strange is I didn't notice oiled plug or cylinder when I had the head of after buying. What could possibly have caused this due to me replacing gasket. Compression tester reads close to 100psi although not easy to do alone.
I can only see the way ahead, head off,cylinder off and take a good look.
Mike

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Ozmadman
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Re: G5 blue smoke and plug oiled.

Post by Ozmadman »

vigo wrote:Recently bought this bike it had lost compression. The headgasket had been in correctly fitted by previous owner. Reassembled with new gasket, starts and runs great,but and a it's a big but, blue smoke and plug and cylinder wet. The bike has a +040 piston and there seems no further cylinder wear. What seems strange is I didn't notice oiled plug or cylinder when I had the head of after buying. What could possibly have caused this due to me replacing gasket. Compression tester reads close to 100psi although not easy to do alone.
I can only see the way ahead, head off,cylinder off and take a good look.
Mike

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There is a small bolt in the cylinder head with a lock nut on, this is actually an oil metering screw which controls the amount of oil to the inlet valve. this needs to be screwed in so it just seats and then screwed out the smallest amount (about a 1/16 to an 1/8" ) Try this first but it will smoke a lot if it is screwed too far out.
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Yak
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Re: G5 blue smoke and plug oiled.

Post by Yak »

IKBA, but I think blue smoke indicates rich fuel mixture. Perhaps carb problem.
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Rob Harknett
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Re: G5 blue smoke and plug oiled.

Post by Rob Harknett »

How long did you run the bike for. If less than about 5 mins try again a bit longer , see if smoke clears., Back in the 1920's with almost manual oiling, a puff of blue smoke indicated it OK. Are you worrying too much over a bit of smoke. I have an old bike that smokes as much as me, we both run OK.
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dave16mct
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Re: G5 blue smoke and plug oiled.

Post by dave16mct »

Blue smoke is definately a burning oil issue. Rich mixture is indicated by black smoke. I think Ozmadman meant 1/6th of a turn (one flat) out for the adjuster screw.
Dave.
vigo
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Re: G5 blue smoke and plug oiled.

Post by vigo »

Thanks gents, yes I thought Oz meant 1/16 turn because the needle was set at less than 1/4 turn so I left it at that. The only thing to add was I also changed the oil for 50. The oil that came out was very thin could the extra viscosity up the oil pressure? I didn't run the engine for 5 minutes more like 2 there was so much blue smoke. Could it be oil from below the piston ie wet sumping?

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SPRIDDLER
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Re: G5 blue smoke and plug oiled.

Post by SPRIDDLER »

vigo wrote: The only thing to add was I also changed the oil for 50. The oil that came out was very thin could the extra viscosity up the oil pressure? I didn't run the engine for 5 minutes more like 2 there was so much blue smoke. Could it be oil from below the piston ie wet sumping?
Just idle thoughts as I'm not very familiar with Lightweights, but I doubt that it's wet sumping as there isn't the head of oil above the pump as there is on the H/W engines with the remote tank. :?
I think the oil feed to the inlet valve is through a drilling in the cylinder barrel. Perhaps the head gasket is leaking oil from that feed into the combustion chamber?
Did you anneal the new head gasket?
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56G80S
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Re: G5 blue smoke and plug oiled.

Post by 56G80S »

Brain fart. Delete post.

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vigo
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Re: G5 blue smoke and plug oiled.

Post by vigo »

I checked the engine oil today and it's down, a lot. After changing oil a few weeks ago and recently running for 2 minutes oil level down about 3 inches, it can only be in the sump. Either not scavenging fully or leaking badly across pump.

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vigo
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Re: G5 blue smoke and plug oiled.

Post by vigo »

Sorry Spriddler, No I didn't know to anneal the gasket. I understand there is no head for wet sumping and haven't yet checked the sump. If I find no oil in the sump I think you must be right. So what are the details for annealing please and can I use the gasket I have just fitted?

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