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Thin oil with white bubbles after carb removal

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Thin oil with white bubbles after carb removal

PostAuthor: Knaks » Sat Nov 11, 2017 4:38 am

G’day again, ladies and gents.

I recently changed out the intake manifold as the old one had cracks all over. I removed the tank, fuel pump, carb and obviously intake manifold (PITA to put back on!) and I had trouble remembering where all the hoses on the fuel pump, petcock and carb went :ops: I looked at some photos and think I put them on right because she started up without any problems after reinstalling everything. After a few rides I thought I’d change the oil when I noticed these white bubbles? I’ve put new oil in and done about 100km and dumped the oil to check and there’s still white bubbles! And I also noticed the oil was watery thin at room temp. Any ideas?

I’m guessing the bubbles are water because they come together into a bigger blob when moved. I noticed after a few days sitting it turned milky and thick

Cheers everyone :(
2005 xv250
Biltwell frisco bars.
17t/front 40t/back sprockets.
10" struts.
Slash cut drag pipes, baffles removed.

Knaks
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Bike year & model: 2005 xv250
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Re: Thin oil with white bubbles after carb removal

PostAuthor: faffi » Sat Nov 11, 2017 6:05 am

Water will not make the oil very thin in my experience, and they do not mix. Fuel will. You may have a carb (or both) where the float needle no longer manage to seal fully, causing fuel to overflow and enter the oil through the cylinder. If this is the case, not only will your engine wear rapidly as fuel wash the oil off the cylinder walls (and once enough in the engine also through the moving internal parts), but in a worst case scenario your crankcases can be blown apart by an explosion.

Most likely, though, you have not caused much real harm yet because due to the design, fuel will only overflow with the engine running, limiting the amount. With a manual petcock and no fuel pump you risk hydro-locking and damage like a bent conrod.
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Bike year & model: 1982 XV750SE with XV1100 engine, XT600Z shock absorber, 18" Seca rear wheel
Sex: Male

Re: Thin oil with white bubbles after carb removal

PostAuthor: Knaks » Mon Nov 13, 2017 3:34 am

I think it might be both petrol and water leaking in. The oil was thin and smelt like petrol and there is definitely a teaspoon or so of another liquid that isn’t mixing with the oil at all. Where exactly would water be getting in? I’ve recently changed to pod filters and got rid of the chrome pod that comes stock so maybe that has something to do with it? Just really flustered as I don’t even know where to start or what to look for.

Thanks for the reply mate
2005 xv250
Biltwell frisco bars.
17t/front 40t/back sprockets.
10" struts.
Slash cut drag pipes, baffles removed.

Knaks
Junior Membership
Junior Membership
 
Posts: 9
Joined: Wed Apr 05, 2017 7:16 am
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Bike year & model: 2005 xv250
Sex: Male

Re: Thin oil with white bubbles after carb removal

PostAuthor: faffi » Mon Nov 13, 2017 5:23 am

Water can enter through the carbs, either via the filters or through the fuel, but the former is likely to just be passed through the engine and into the exhaust, the latter more likely to give running issues. However, if you have an overflow issue combined with water in the tank (from a leaky tank cap), you could end up with both fuel and water in your oil.

Note also that you will always get condensation in your engine. Usually, this will evaporate during a longer rider. If the engine ventilation is partially blocked, however, and/or you only ride for very short distances in cold weather, that condensation will accumulate in/on the oil and can even foam.
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Bike year & model: 1982 XV750SE with XV1100 engine, XT600Z shock absorber, 18" Seca rear wheel
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