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Crankcase ventilation

Discussion in 'XJ Technical Chat' started by tabaka45, Nov 3, 2022.

  1. tabaka45

    tabaka45 Well-Known Member

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    My Honda Rebel started pouring oil out of the left side flywheel cover. Turns out that the crank shaft seal had blown out, apparently because the crankcase ventilation system failed and crank case pressure forced it out. The Rebel has a strange system that vents to the air box but also has another vent tube that has to be drained every so often to prevent it from clogging the entire system. Is there anything like that on my XJ700N, or is it just a simple vent tube to the breather.
     
  2. jayrodoh

    jayrodoh YimYam Premium Member

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    Can’t answer your question but I have a Rebel I've had for 9 years and wasn't aware of this either. Looks like it collects moisture and oil from the breather system but does have to be drained manually. Thanks for the heads up.
     
  3. Dan Gardner

    Dan Gardner Well-Known Member Premium Member

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    I don't recall ever seeing anything about crankcase ventilation maintenance in any XJ service manual or anything...
     
  4. hogfiddles

    hogfiddles XJ-Wizard, Host-Central NY Carb Clinic Moderator Premium Member

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    Nope.... xj crank case vent goes to the airbox and it’s uphill all the way anything in the tube will drain back down. Anything in the airbox will drain does the airbox drain tube
     
  5. tabaka45

    tabaka45 Well-Known Member

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    That explains the extra drain tube on the Rebel The vent tube comes out of the crankcase and has a bend in it like a p-trap on a sink, and then goes on to the breather.
     
  6. bensalf

    bensalf Well-Known Member

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    my Honda Goldwing was the same, part of the maintenance shedule was to remove the plugs on the drain tubes (there were 2) and drain the water out, got an eggcup full out each time
     
  7. SecaMaverick

    SecaMaverick Active Member

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    This is another reason replacing the stock airbox with pods can be problematic. There's nothing for the breather hose to plug into. (There are other posts about this on the forum, as well.)

    My XJ550RH came to me 21 years ago with pods and no stock airbox to reinstall. The PO had a small, round "Harley-style" breather filter stuck on the end of the short hose. Problem is, the frothy oil you're talking about likes to vaporize through the filter and spread itself all over the bike, from that area back. The hose was too short and the filter was too close to the engine.

    In time, I found that mounting an EMGO crankcase breather filter (with bracket) back under the rear fender -- near the right turn signal -- on a really long length of hose to the crankcase, mitigates most of that oily vapor mess.

    One day I hope to find an original airbox to revert the setup from pods to stock... although I'm not quite ready to take the engine out again for the clearance needed to do that more easily. (Oh, and a custom fuse box is mounted to the back side of the battery box, where the airbox would go. Hmm. That would need relocated. Always more work to do!)
     
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  8. Phoenix starr

    Phoenix starr Member

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    I gotchu on an original airbox if you're still looking. I pulled mine and installed a murray set up. I found this forum because I was wondering what I should do with the crank case vent. There is quite alot of "vapor"(smoke) coming from the vent. How much is too much?
    I just had mine running its original path but I put a small engine fuel filter on it to keep the filth out.
    I think that the vaper coming out was destroying my ride quality as it was inhaled by the carbs, which is odd considering it used to go to the air box.
    If youve got any helpful input lmk
     

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