I have an '01 V-Star, is it normal to have oil in my air filter? It's not running to good, so I decided to replace the plugs and noticed this. I haven't noticed this before. And why would I have this issue? Please can someone help me with this. John
A fair number of bike's will have crankcase ventillation hoses which connect to the air box. If the bike is overfilled with oil, or perhaps some other condition exists which is causing oil to be sent through the crankcase breather into the air box. If it's not a lot, I wouldn't worry too much, if it is a lot I'd check the oil level first.
This is totally normal on these V-Twins. In fact Yamaha has run the crank vent hoses to little nozzles on top of the throttle bodies on the latest bikes like the Roadliner and the Raider. That way the oil mist from the breather gets sucked back into the engine.
Yes when you overfill, there will be more oil coming out of it, but even at normal levels you will always have some oil mist come out of it that over time builds up a layer of stinky gui oil.
You say that the bike isn't running well and that there is oil in the air box. If it were me, I'd do a compression check on both cylinders. Reason being, if you were to have a bad compression ring, head gasket, or valve guide problem (does it tick, tick, tick?) the excessive blow by caused by that problem will manifest itself through the crankcase vent, which in your case is routed into the airbox, thus oil in the airbox. For your sake I hope that it is just overfilled with oil.
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