Fuel in primary

Discussion in 'Transmission' started by RoadsterRick, May 22, 2012.

  1. RoadsterRick

    RoadsterRick New Member

    Left the petcock open on my 1980 XLS and filled the cylinders with fuel. Pulled the plugs out and turned it over to blow out gas. put a cap full of oil in each and turned over to re-lube rings etc. changed the oil and filter and thought I should be set. Fired it up and noticed oil blowing out of Primary vent. Checked the oil level in primary and oil/gas poured out if screw hole. about 4 ounces over filled and has fuel mixed in it. How did fuel get in there???. this is an 1980 so no vent between crankcase and primary. A lot of gas poured down the outside of primary, could it have gone in through the shifter seal?? (seal is bad, One of the last leaks I have to deal with.)..... Any thoughts on this???
    Last edited: May 22, 2012
  2. Breeze3at

    Breeze3at Well-Known Member

    How long did it sit with the petcock open? Bike on side stand? Sounds like gas leaked past rings, into crankcase and then past the left side crankshaft seal into the primary. Not something that happens overnight unless the rings and crank seal are real weak.
  3. Jack Klarich

    Jack Klarich Expert Member

    Agree with Breeze, the crank seal is leaking, gas is thinner than oil and will seep past a weak seal easily
  4. RoadsterRick

    RoadsterRick New Member

    I left the bike for about 7 hours. Drained about 1 gallon of fuel from tank. filled the cylinders!. lots of gas on the ground..... The rings are in good shape ..based on the 155,153 psi comp.check.. I do believe you are both right about the fuel getting through the crank seal from the "Full" crankcase. I''m going to change the primary oil today and keep an eye on the level to see if I need to replace that seal.

    Thanks for the replies. :bigsmiley12: