Oil Leak

Discussion in 'Engine, Fuel and Exhaust' started by anthonydiaz85, Dec 16, 2012.

  1. anthonydiaz85

    anthonydiaz85 Member

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    I know evos are notorious for leaks, but i have a nasty leak coming from the forward head where the banjo bolt of my carb crossover is screwed in. Ive tried tightening the bolt in hopes the leak would stop but no sucess. I have a 80' evo with an S&S carb. The leak occurs while riding and at a stand still. Any ideas on what i can do to eleminate this problem? Oil gets all over my hard bags. Thanks in advance.
     
  2. fin_676

    fin_676 Experienced Member Staff Member Moderator Contributor

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    I am just a wee bit confused on this one as the 80's evo motors did not use a banjo bolt in the heads it should be a solid bolt as the breather heads were introduced mid way through the 92 model build but not implemented till the 93 model
    Do not over tighten the head breather bolts as you may strip the threads from the head
    remove the bolts clean up the mating surfaces there may be some washers depending on the air cleaner backplate that is fitted that need to be clean and in good condition
    A thin film of a non setting gasket compound on each of the mating surfaces should prevent any oil weep

    Brian
     
  3. Breeze3at

    Breeze3at Well-Known Member

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    It sounds like he's got a breather bypass kit (see link). the banjo could be warped, or just a bad gasket. Make sure there is no obstructions in the line to back up the pressure, then replace gaskets. You can make them yourself.
    Harley 93 98 1340 Screamin Eagle Breather Kit 29310 93 | eBay

    P.S. If it's part of your carb mount, make sure nothing is binding, use washers to shim.
     
    Last edited: Dec 16, 2012
  4. anthonydiaz85

    anthonydiaz85 Member

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    First off, thanks for the quick reply. This problem is on 1993 Heritage classic with a stock evo motor. Im going to try your advice and let you know how it goes.

    Thats the exact system i have on. I remember when I installed it with my semi-mechanic friend we had to add on an extra inch of manifold just to get the hole in the banjo lined up with the crossover. Ill remove the assembly and check for what you pointed out. Are the banjo bolts neccesary in the header? The problem is on 1993 stock evo. Thanks for your reply too. I appreciate the help
     
    Last edited by a moderator: Dec 16, 2012
  5. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    You might want to check the unbrella valve in the heads. This valve can get brittle and do not seal correctly and let oil instead of oil mist enter the breather holes. You did not mention the milage but you could also have some worn valve guide or piston rings.
     
  6. Breeze3at

    Breeze3at Well-Known Member

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    The stock head breather system used hollow bolts with 90 degree holes near the head that let the crank case gases flow into the air cleaner backing plate, where it was sucked up by the filter. Later models bypassed the filter and vented right at the carb. throat. Yes, the heads must be vented in some manner.

    I think Fin read the o.p. as the bike being a 1980's evo instead of a 80' (inch) evo. Them Scots use different key pad abbreviations than we do. :newsmile036:
     
  7. anthonydiaz85

    anthonydiaz85 Member

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    I should have considerd the language barrier:s\

    When I get home tonight im going to break down the cleaner and base plate and see what it looks like. I have a feeling the problem is going to have something to do with the fitment of the banjo bolt and the crossover based on your info. I'm considereing buying the S&S stealth air cleaner kit and try a whole new system but im going to weigh the problem when I see it and decide if I need to get something new.

    I hadnt even considered that. I'm going to run through the possible option of this breather hole issue. Hopefully the issue is an easy fix. But if not im going to have to move to this as the possible issue. (sounds like an expensive fix)
     
    Last edited by a moderator: Dec 16, 2012
  8. Redfish-Joe

    Redfish-Joe Senior Member

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    IF and I say again IF the banjo bolt uses a copper washer seal you can remove it and heat it good and hot with a propane torch to soften it up again. As they are compressed the become harder and less likely to seal.
     
  9. anthonydiaz85

    anthonydiaz85 Member

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    Thanks Joe. PLaying with flames always makes my night better anyway.
     
  10. Breeze3at

    Breeze3at Well-Known Member

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    The early umbrella valves had a tendency to harden and lose sealing ability.
    The umbrella's themselves are about $2 ea. You'll spend more on cover gaskets.