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Thread: R90/6 Breather valve question

  1. #1
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    Question R90/6 Breather valve question

    For years I have periodically heard an odd sound when the bike is idling at a stop light..a sound similar to turkey gobbling. Is that the breather valve malfunctioning and what does this valve do? Where is it located and how difficult is it to replace? Lately I have noticed transmission oil leaking from the rear casing. I friend told me he suspected the breather valve. Advice and suggestions most appreciated.

  2. #2
    Rally Rat
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    Oh yes, the ole turkey gobble....

    As it was explained to me, (it is quite common), the bikes were designed to pull air into the crankcase as necessary through the rear main seal (!). That is what is making the gobble sound, as the crankcase pressure increases and decreases with the cylinders going in and out.

    The actual breather is on top of the engine, next to the starter, and has a rubber tube going to the right airtube. There is a new design breather that can be put in to replace your breather, or you might be able to clean it up. Either way, it is some work to get into it, but not a great big deal. There are several people who make special tools for pulling the breather.

    Jeff Trapp is a good guy, and can help with advice. His website for the tools, etc:

    http://www.northwoodsairheads.com/Tools.html

  3. #3
    shire2000
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    Funny someone brought this up. My wife's little R45 has made that noise since new. 90,000Km later, it still makes the noise. I don't think it has done any harm and when we go for a ride together, I get to tell her to "Get that Turkey movin'." She doesn't appreciate my humour and thinks that the noise is "cute" and makes her bike unique.

    Of course the R45 is so gutless, turkeys could probably out run it.


  4. #4
    Administrator 20774's Avatar
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    Here's a good page with illustrations for replacing the breather. For a /5 but it's all about the same.

    http://www.bmwscotter.com/procedures/procedures.htm

    On my /7, the oil mist is routed forward through a tunnel in the engine casting. Just forward of the breather housing, in a well in the tunnel, is a small hole which allows the condensed oil mist to drain back into the case. If your bike has this feature, be sure that the small hole is clear. Otherwise, pooling oil will continue to grow and make a mess of things.
    Kurt -- Forum Administrator ---> Resources and Links Thread <---
    '78 R100/7 & '69 R69S & '52 R25/2
    mine-ineye-deatheah-pielayah-jooa-kalayus. oolah-minane-hay-meeriah-kal-oyus-algay-a-thaykin', buddy!

  5. #5
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    Quote Originally Posted by rbryson View Post
    For years I have periodically heard an odd sound when the bike is idling at a stop light..a sound similar to turkey gobbling. Is that the breather valve malfunctioning and what does this valve do? Where is it located and how difficult is it to replace? Lately I have noticed transmission oil leaking from the rear casing. I friend told me he suspected the breather valve. Advice and suggestions most appreciated.
    breather valve will not cause transmission/gear oil leak

    are you sure its gear oil? smell it-- its very pungent

    you may have engine oil leaking past the rear main seal onto the shelf below the gearbox

    gobbling may be a symptom of excessive crankcase pressure, which would also cause a leaking rear main.

    or, your breather valve itself might be leaking-- at the gasket or the rubber hose

    you can replace with the more modern reed valve [about $20]. it can take quite some effort to pop the old valve out, but there is plenty of info online. a special tool is really not necessary.

    you dont have the breather return drain hole on a /6

    you need to have a look to see whats up

  6. #6
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    Thanks guys! 20774 especially, for the link to photos showing so clearly how to do this. I am never disappointed with the quality of advice I get from this forum. Cheers.
    Rb

  7. #7
    #4869 DennisDarrow's Avatar
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    I did the replacement last spring on my R90/6.

    A couple of thoughts:

    I made a simple puller with a couple of "S" hooks looped through a length of cable. I bent the hooks so they would not come off of the cable and fall into the engine case. Then placed a length of 2X4 on the frame tube, got my 24" breaker bar, on end on the 2X4 with the cable going around it, situated the hooks so there was a spread across the webbing of the old breather valve, and then "popped" tension on the breaker bar. It came right out.

    Yes, you can use the old cover. Pay particular attention as to the placement of the angle of the new valve. It, for me, would only fit one way.

    The guys at "Vech" helped me a lot with the parts and advice.

    Some folks say that you dont need the valve and that it will freeflow through that vent hole back into the engine. Not being a n engineer that designs engine I don't know about this method; so I just go back with what the factory guys did. For me, one must contain that oil mist someway, not just let it float till it settles, like all over the starter motor, etc.

    Anyway, good luck. It really isnt a bugger to do. Maybe 2 or 3 hours.....Dennis

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