Crankcase vent system

Discussion in 'WERA Vintage' started by john westcott, Jul 13, 2020.

  1. john westcott

    john westcott Well-Known Member

    Looking for a way to plumb the oil filler hole for a vent hose. Any ideas?
  2. VFR#52

    VFR#52 Well-Known Member

    If you are going to vent the motor do not use the filler hole as it has so much pulsing when engine is running it can pump oil out of motor quickly.
    Use the valve cover for a vent.
    Now I'm assuming we are talking about a 4 stroke.
    Any questions just PM me

  3. grasshopper

    grasshopper Well-Known Member

    What bike?
  4. john westcott

    john westcott Well-Known Member

  5. CharlieY

    CharlieY Well-Known Member

    Hello John.....

    I'm not sure if this will help, but I made about a dozen of these for the CB350.....sounds like what you are looking for. May not fit yours, maybe its an idea for you.

    The CB350, in stockish form, or moreso in the big overbore form AND high RPM, tend to pressurize the crankcase alot, and have been known to blow out seals to the clutch pushrod and causes "weepy" gaskets....both bad for a track environment of course. Some apply a "band-aid" with a retainer to that seal, but never address the real problem.....I used a smaller hose for awhile, but it wasnt enough....I also used the electric starter location, but didnt favor it because of the length of hose.

    Anyhow, depending on the dipstick location (high or lower), with the outlet pointed in the upward direction I've never had an issue with leakage. I use large hose to help with volume.

    Attached Files:

  6. john westcott

    john westcott Well-Known Member

    That's what is happening with mine at the countershaft and main seal on the same side.
  7. CharlieY

    CharlieY Well-Known Member

    You are headed in the correct direction sir!....IMO of course.

    I forget the thread to the CB dipstick, but its a strange one.....25mm x something (fine).....what are the odds yours is same????
  8. john westcott

    john westcott Well-Known Member

    I will have a look and see, thanks for the interest.
  9. CharlieY

    CharlieY Well-Known Member

    Any time.

    Lemme know if you want one.....they are nice alum AN aircraft fittings, anodized. I haven't sold any yet (lazy) but was thinking around 50.

    I may have a blank left, and maybe could get the thread cut for your application.....or sell you the blank, and do as you wish.
  10. john westcott

    john westcott Well-Known Member

    Great I will let you know, going to check Royal Brass and Hose and see what they have.
  11. dave3593

    dave3593 What I know about opera I learned from Bugs Bunny

    I'm a cheap skate. What about drilling a hole right up thru the stock fill plug. Make it the correct size for a press fit (and epoxy) 5 inch long stainless or copper tube. The tube stick out the top of the plug 4 inches and is as large a diameter as possible so it doesn't spit out oil. Put a push fit hose on top of the tube. The hose goes to your catch can. To take out the plug, pull off the hose so the plug can be screwed out. This may be harder if the plug is also a dip stick.
  12. john westcott

    john westcott Well-Known Member

    Dave that's what I did. Thanks every one for the guidance.
  13. CharlieY

    CharlieY Well-Known Member

    Yeah, that was similar to my first attempt too, I just threaded a nipple into the dip-body (dipstick cut off drilled out obviously). The little hose had to help some, but after awhile I didnt consider it as I started looking at how to get the hose second attempt was half an AN fitting welded to the dipstick plug ......that led me to make something "cleaner" as pictured above.

    Oh, second attempt was little hose out of dipstick, PLUS little hose in my starter block-off plate.....third was the welded AN.....then latest shown above.

    Good luck Gents!
    dave3593 likes this.

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