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ET: Engine (Twin) Fogging for Mosquitos


ClassicBiker

Well Known and Active Website User
VOC Member
A curious thing happened to my Shadow this past Tuesday. Before going to our monthly section meeting I started the Shadow and warmed it up. I looked and checked that I had a nice steady oil return, I did. I warmed up the bike and rode the 22-24 miles to the meeting and parked the bike for a couple of hours. After the meeting the bike fired right and I rode away. After going a few mile I had to stop for a light and a cloud of oily smoke blew past me from behind. I looked down and back only to see that I was fogging for mosquitos! :eek: If the smoke pouring out was horrendous. There was smoke pumping out the breather even.:( Crossing my fingers and praying quietly to myself I continued on, hoping the oil would last and the engine wouldn't seize. Well I made it home without further issues. I checked the oil in the tank and it wasn't down too much from when I had left home. Wednesday morning I pulled the plugs and the valve covers to see if I could determine if it was one or both cylinders oiling (both) and if a there was an issue with the valve gear (doesn't seem to be) so I put everything back and started it up. It smoked from the exhaust and oil and vapor dribbled from the breather for about ten or so minutes and then just quit. o_O Now I had the tank cap off and was watching that oil returned (it was) then all of a sudden the volume of oil exiting the return dramatically increased for a few moments and returned to normal, that was when the problem stopped.
Never having had this happen before, is this indicative of wet sumping? If it is, what would cause it to happen in this fashion, in the middle of a ride and not immediately upon start up after sitting for awhile?
Any thoughts or suggestion greatly appreciated.
Thanks
Steven
 

vin998

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VOC Member
VOC Forum Moderator
If it had smoked when you first started the bike on the Tuesday in question before going to the section meet I would have said it was due to the bike having sumped whilst in the garage. As it didn't start smoking until later that night after you had done 25+ miles I would say the oil level built up in the sump due to it not returning to the tank properly and most probably due to the return pipe to the tank been partially blocked with something.
Just a guess
Simon
 

ClassicBiker

Well Known and Active Website User
VOC Member
If it had smoked when you first started the bike on the Tuesday in question before going to the section meet I would have said it was due to the bike having sumped whilst in the garage. As it didn't start smoking until later that night after you had done 25+ miles I would say the oil level built up in the sump due to it not returning to the tank properly and most probably due to the return pipe to the tank been partially blocked with something.
Just a guess
Simon
maybe fungus under the flywheel.
I think you both might be correct. "Fungus" under the flywheel temporarily blocking the return pickup. When this was going on the oily mess coming out of the breather resembled grey mayonnaise like stuff created when a water cooled engine blows its head gasket and the coolant and oil mix. It was rather curious to see this stuff dribbling out of the breather pipe, because unless I've completely missed the plot I believe my Shadow is air cooled and not water cooled.:rolleyes::confused: Now what concerns me is if some "fungus" (for lack of a better term) was blocking the pickup it didn't get blown out through the breather as that isn't an active pump as such, but must have been picked up by the return and dumped back into the tank.:eek:
Time for an oil change I think.

Check to see if the breather pinion is still an assembly.
I shall do that. I had wondered if something was amiss with it. So I ran the engine with the ATD cover removed, thinking that would allow the engine to breathe easier. It still smoked and dribbled. So I let the engine cool and then replaced the ATD cover and ran it again and that's when it cleared. I'll report back on what I find.
Steven
 

b'knighted

Well Known and Active Website User
VOC Member
Decades ago I ran a Comet with its ATD cover removed and was surprised at just how much oil was thrown out. I forgot all about this until recently when I ran a different Comet with its ATD cover removed and was again surprised at just how much oil was thrown out. I won't do it again. Do twins not normally dump and spray oil out when run without the cover?
 

mercurycrest

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VOC Member
I agree with Ian, you should have had oil all over the place! You might like to check how much oil is in the return line at the front ex. valve fitting. The "mayonaise" is condensate... You need to ride it further and properly warm the engine up. ;)
 

ClassicBiker

Well Known and Active Website User
VOC Member
Decades ago I ran a Comet with its ATD cover removed and was surprised at just how much oil was thrown out. I forgot all about this until recently when I ran a different Comet with its ATD cover removed and was again surprised at just how much oil was thrown out. I won't do it again. Do twins not normally dump and spray oil out when run without the cover?
Not much it didn't. I didn't completely remove it though. I backed off the six screws and it pulsated a bit like a one way valve. A lot of oil vapor came out though. It has me thinking about the pros and cons of something like the elephant trunk breather with/without a one way valve and a catch can.
Steven
 

ClassicBiker

Well Known and Active Website User
VOC Member
I agree with Ian, you should have had oil all over the place! You might like to check how much oil is in the return line at the front ex. valve fitting. The "mayonaise" is condensate... You need to ride it further and properly warm the engine up. ;)
I agree it's condensate and that I should ride it further and more.:D But the fact of when it happened is what perplexes me.:confused: That that is persisted through till the next day and cleared inexplicably is what worries me. :( When I removed the front rocker cover there wasn't an inordinate amount of oil present nor was it starved for it either. This is what mystifies me. I have some old nasty looking rocker covers that I might modify with window to see the oil flow in the rocker areas.
Steven
 

wmg73141

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Non-VOC Member
"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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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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VOC Member
"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

Well Known and Active Website User
Non-VOC Member
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

Well Known and Active Website User
VOC Member
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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VOC Member
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

Well Known and Active Website User
VOC Member
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

Well Known and Active Website User
VOC Member
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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