Hi, Anonymous you're getting ready to go riding you pull out the dipstick to check your oil level and are greeted with the unmistakable smell of gasoline. What happens next depends on the following:
1. You have experienced this before and do not start the engine but do change your oil and filter leaving it 1 quart low until the engine reaches operating temperature then top off as necessary.
2. The amount of time your bike has been sitting since the last time the engine was running.
3. The amount of gas and contaminants in the tank.
4. The oil pump location, exterior or interior.
5. The condition of your petcock gasket/seal/diaphragm.
If your gas tank was low and you start the engine probably nothing you would notice but if your gas tank was full and you start your engine the oil/gas mixture can blow into your air filter, come streaming out of your crankcase breather hose, and launch your oil tank cap followed by a blast of oil. The mess can be minor or you need to call a Hazmat team for assistance. This will also happen if you overfill your oil tank.
Next is the how and why gas can get into your oil tank/system:
a. The vacuum petcock rubber/diaphragm fails, which allows gas to flow from the fuel tank through the petcock, through the vacuum line into the intake manifold, then into the combustion chamber, where it seeps past the piston rings and into the bottom end.
3. Nonvacuum petcocks that are not turned to the off position will patiently wait until contaminants from the gas tank build up in between the carburetor needle and seat breaking the seal thus inviting gas to enter the combustion chamber eventually finding it's way into the bottom end and the oil tank.
4. Bottom line if you're not going to ride your bike for a while turn off the petcock.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
ASK THE MXPERTS CAN GASOLINE GET INTO THE CRANKCASE OF HONDA CRF450 Anyone with gas in oil 2013 Honda CRF450R
Honda CRF450X 2005 Service Manual
Honda CRF450R Owner Manual
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