This is not the ideal forum for this question, as this pertains to a motorcycle, not a car. But, both use 4 stroke engines, so am hopeful I can get some guidance here. No one else has been able to solve this puzzle.
My motorcycle, an Italian Aprilia brand bike, uses a dry sump, vertical V-twin engine. It is fuel injected, 4 valves/cylinder, 2 plugs per cylinder, watercooled. At at about the 775 mile mark, 150 miles after the first service, it began smoking from the tailpipe, only on cold starts, and only after it sits for at least several days. You can see a movie of the smoking at
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. Scroll down to movie section. Warning, big file. It is a whitish blue smoke that has a heavy exhaust fuel smell to it. The smoking is not consistent. Sometimes will do it, other times nothing at all, but seems to be getting more and more frequent now. But, I believe it started suddently. The smoking may last a few seconds to nearly a minute. When running and smoking, shutting down the engine and immediately restarting, the smoke seems diminished, if not gone. Oil consumption is low, with a few ounces used in 1400 miles. There is no smoking I can see when the engine is hot. A few other owners have the same problem. The problem does not seem to get much worse with time or mileage for these owners. No one knows what it is. I find it very hard to believe valve guides or guide seals have given up in less than 800 miles, and suddently on top of that. In addition, why is the smoking inconsistent? The engine has never been abused or overheated. No coolant consumption. The engine has a propensity for blowing oil into the air cleaner housing, but ruled that out by cleaning the housing, firing the engine (smoked), and rechecking the housing. It was clean with no oil seen. One owner had a cracked cylinder head, which leaked oil into the exhaust port. The bike has gas anlyzer ports for each exhaust pipe, so it will be possible to open these, partially plug the exhaust, and then which cylinder(s) smokes.
Anyone with ideas? I thought about wet-sumping, since the oil tank level does drop fast after the engine is stopped. I also wonder if the smoke is fuel, due to a faulty fuel injection circuit, or...?
- Phil