ET: Engine (Twin) Fogging for Mosquitos; Valve Guide Issues and Solutions

wmg73141

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"unless I've completely missed the plot I believe my Shadow is air cooled and not water cooled"

For every eight pints of petrol you burn you get ten pints of water, usually it goes down the exhaust pipe with the rest of the pollution.

How about sticky rings letting by?
 

chankly bore

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Only drama I ever had with a Guzzi I rode for twenty years was stuffed guides and rusted breather ball valve, both due to condensation. Too many short trips; it was a ride to work machine. As well as all the above good advice, maybe one grade thinner oil and go everywhere the long way.
 

davidd

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I would be interested to know the results of a leak down test. This would tell you if it is your valves, rings or both. If smoke is coming out of the breather then I would assume it is getting by the rings. But, it seems to me that this would tell you whether you had a sealing problem or an oil system problem.

I am not sure what to say about the oil system. I have never had smoke come out of the pipe even when using a quart every two hours. This happened when teeth came off a nylon gear and packed up in the oil return banjo on the bottom of the UFM. On that same trip I lost a bit of the sealant that sealed the timing chest just above and a little rearward of the ATD. It pumped out oil like I had severed an oil artery! The paddle wheel effect of the gears pushes a surprising amount of oil at the crank case seals at a high rate of speed.

As for the clear rocker cover, it was pointed out to me on a twin recently:

Rapide RT side.jpeg


David
 

Peter Holmes

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"unless I've completely missed the plot I believe my Shadow is air cooled and not water cooled"

For every eight pints of petrol you burn you get ten pints of water, usually it goes down the exhaust pipe with the rest of the pollution.

How about sticky rings letting by?
Is that a factually correct statement for all engines that breathe in oxygen and burn petrol?
 

wmg73141

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Is that a factually correct statement for all engines that breathe in oxygen and burn petrol?

As a generalised observation -- yes. But don't ask me for details as I am not a chemist!

Engine type/design, engine management systems, (ECU's 'an all that jazz) and fuel composition will all have their effect on hydrocarbon fuelled prime movers.
As an example that's where the dribble of water that comes out of your car's exhaust on a cold morning comes from. The extreme case would be an engine fuelled by compressed hydrogen & oxygen, in that case only water would be the exhaust product. In those examples where only compressed hydrogen is carried and the oxygen is obtained from the atmosphere then there will be Nitrogen oxides (NOx) as well because our atmosphere is predominately nitrogen.
 

ClassicBiker

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David,
I'm going to do as you suggest, a leak down test. I also read in Richardson's last night about 1) bypassing the rocker gear temporarily to determine if excess oil is finding it's was into the combustion chamber via the valve guides. If the smoking stops then it's the guides. 2) Temporarily soldering up the oil jet that feeds the cams and back of the cylinders, if that stops the smoking then the engine requires restricter discs, if it doesn't have them already. According to Richardson the jet can be as low as 140, but he recommends not to deviate from the standard 170 and control the flow via the discs. KTB says the hole size in the discs is 0.025 - 0.30. I know some on this forum have said they don't even drill the oil way in the liner, so gradually reducing the hole doesn't worry me massively.
So:
1) Check breather assembly is still an assembly.
2) Leak down test.
3) Bypass rockers temporarily.
4) Block oil jet temporarily.
5) Check rings.

Watch this space for results.
Steven
 

greg brillus

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So far all the symptoms sound like an oil tank that can not vent correctly. The smoking sounds like a problem caused by the flywheels running in a bath of oil.................The piston rings cannot wipe away that much oil, and hence the smoking.
 

davidd

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It is a good point, Greg. I like the leak down test because I think it is important to check the existing condition of the bike, but as you point out you can't start too far down the chain. I make a habit of enlarging the vent holes in the caps because I think they are too small for racing and can fill with wax, polish or crud very easily. It would also explain why the bike ran well with the cap off.

David
 

highbury731

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It is a good point, Greg. I like the leak down test because I think it is important to check the existing condition of the bike, but as you point out you can't start too far down the chain. I make a habit of enlarging the vent holes in the caps because I think they are too small for racing and can fill with wax, polish or crud very easily. It would also explain why the bike ran well with the cap off.

David
how big do you drill out the oil cap vent hole?
 
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