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Crankcase venting

Discussion in 'The Garage' started by Gator xs2, Jul 9, 2019 at 6:06 PM.

  1. Gator xs2

    Gator xs2 XS650 Addict

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    I just read a interesting article on the xs650 crankcase venting. From the early design to the best they could come up with over the years. According to the article the earlier venting, quote “ leaked like a true Brit” That’s me. Anybody got some ideas? Besides a catch can?
     
  2. timbeck

    timbeck XS650 Junkie XS650.com Supporter

    I understand that the oil level plays a large part in blow-by. You can try running a bit less oil. I'm sure more technical responses will be forth coming.
    tim
     
  3. Gator xs2

    Gator xs2 XS650 Addict

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    Thanks Tim. I saw that. Yamaha actually recommended cutting back to 2.5 liters. They still leaked. I’m thinking of venting it into a non structural part of the frame. But that may be a bad idea. And there goes originality. Thanks. Maybe it’s just gonna have to leak. The article I read said to keep the vent tubes away from the wheel. Oh well. Thanks again Tim.
     
  4. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    It's a gravity thing. Connect your vent tube to a 6 foot long tube, mount the 6 foot tube so it sticks up into the air. The air will exit the tube and the oil will drip back into the engine. :shrug:

    Scott
     
    TwoManyXS1Bs likes this.
  5. Gator xs2

    Gator xs2 XS650 Addict

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    Thanks Scott. I was wondering about that.Where am I supposed to run a six foot tube? Down under the bike and back up? Seems like it would puddle up like a snorkel.
     
  6. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Yep, that would be the problem, snorkel is the right term.

    I don't understand the whole system, no matter how much I read here. On my Honda's very little oil gets into those trash cans, mostly condensation vapors, and that takes a long, long, long time to accumulate.

    Scott
     
  7. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    In my mind...…..those vent tubes should be pointing up, instead of down.
     
  8. timbeck

    timbeck XS650 Junkie XS650.com Supporter

    When I change oil I put 2 quarts of oil in and have no blow-by. I have two XS650's and they both like it like that.
    tim
     
    arcticXS and Gator xs2 like this.
  9. Gator xs2

    Gator xs2 XS650 Addict

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  10. highboy_coupe

    highboy_coupe XS650 Addict

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    Last edited: Jul 10, 2019 at 8:26 AM
  11. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Gator xs2 likes this.
  12. Tim Meaders

    Tim Meaders Not another Old man on an Harley! XS650.com Supporter

    You can also make the "snorkle" multi-purpose by adding a bright red safety flag. This will greatly improve your visibility will riding.;)
     
    Gator xs2, mrtwowheel and gggGary like this.
  13. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    I have also thought of using the frame backbone as a "catch can", oil air separator!
     
  14. grizld1

    grizld1 Grumpy old man Top Contributor

    +1 re. 1-way valves. Testing by pro tuners has pretty well debunked the claim that they'll increase power, but they'll definitely reduce oil loss out the breather. I use the Krankvent valve from ET Performance (no longer available, manufacturer appears to be gone too). With the crankcase filled to the top mark on the 1977 dipstick there's almost no oil loss between changes, even after prolonged highway speeds. There are less expensive breather valves available with members reporting good results. A quick search will turn up plenty of good information.
     
    Gator xs2 likes this.
  15. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    How 'bout a bag on the vent tubes?

    SheldonBag.gif

    Or a balloon.
    About 4" diameter oughta work...
     
  16. Gator xs2

    Gator xs2 XS650 Addict

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    Thanks guys. I’m gonna see just how bad this thing spews before I take action.
     
  17. SEd27

    SEd27 XS650 Enthusiast

    +2 on the one way check valves.

    https://www.dormanproducts.com/p-9590-80190.aspx

    I use two of the Dorman units and vent onto the Uni foam filters for the carbs. They are fairly inexpensive and easy to mount.

    In my experience there is minimal oil discharge.
     
    Gator xs2 and nhsteve like this.
  18. nhsteve

    nhsteve XS650 Enthusiast

    Going to try this route myself after (I think) 5twins suggested it along with a pair of UNI filters. Very close to getting it on the road. Will post up my thoughts after I've had a chance to run it a bit.
     
    Gator xs2 likes this.
  19. DirtyErnie

    DirtyErnie Renaissance Hick

    I'm using a brake vacuum check valve from like an '88 ford F150. It fits, and then I think it's 1/2" vinyl tubing down to the crank case and back up (U-shape) around the spine of the frame, ending between the pods. That tube is topped with a small K&N type gauze breather filter. Seems like there's always a scunge of oil film around that part of the bike, but it doesn't bother me much. I also did the old what's-his-name (Mitten?) mod to the breather itself and that may have been a mistake. Oh well, stuffed it with loose, coarse-grade steel wool.
     
    Gator xs2 likes this.
  20. XSLeo

    XSLeo XS650 Guru Top Contributor

    On my 75 it was missing the cam chain adjuster cover. I picked up a complete 80somewhen engine at a salvage yard. I used the complete adjuster on the 75 .
    I tried the mods to the 75 breather. Didn't help much. I took the breather off the 80+ engine. I added the Dorman power brake valve and ran a 3/8 inch hose from there down, like stock. I don't notice any drips out of the hose, end always dry.
    I have been thinking of making adapters that fit the carbs that move the Uni-Filters back a bit so I can add fittings to hook the breather hose to like the later models do. This way any blow by in the engine can be drawn back in the carbs and burnt.
    Leo
     
    Gator xs2 likes this.

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