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Author Topic: Crankcase vent  (Read 1010 times)

Offline marcmax

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Crankcase vent
« on: October 24, 2014, 07:41:15 PM »
Can anyone tell me where the crankcase vent connects on an engine with the clamshell airbox and round airfilter? I had a flat airbox and the crankcase vent went into a "T" fitting that went into the carb intake elbows where they connect to the airbox. It won't work that way with the round airfilter between the two halves of the airbox.
« Last Edit: October 25, 2014, 05:33:23 PM by Bob_Roller »
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1982 R65ls    1984 R65ls

Offline Barry

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Re: Cranjcase vent
« Reply #1 on: October 25, 2014, 04:27:31 AM »
On the clamshell air box the vent goes to a T fitting and then routes to the centre of each air box outlet.  This is the only picture I have. It's not great and taken with the breather cover removed.  You can see the rubber hose above the breather which turns down and backwards at 45 Deg to a T and then splits to each side of the air box.  The ends of the hose on each side are cut at an angle and are positioned in the centre of each air box outlet. They are not to touch the sides.

« Last Edit: October 25, 2014, 04:51:29 AM by bhodgson »
Barry Cheshire, England 79 R45

Offline marcmax

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Re: Cranjcase vent
« Reply #2 on: October 25, 2014, 05:14:56 PM »
Since my R65LS originally had a flat airbox and I bought this clamshell airbox at a swap meet it may be a little different. There is only one hole into the airbox that goes into the center of the air filter. It is the round hole to the left of the air filter. I may just route a hose into the center of the air filter and see how that works. I can't see getting a tee and assorted elbows squeezed into the center of the air filter..
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Offline Barry

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Re: Crankcase vent
« Reply #3 on: October 26, 2014, 03:43:03 AM »
That looks like an older clamshell airbox where the breather vented into the right carb only.

In my pic above all of that plumbing is in the starter cavity and the breather vents into the centre of the spigot that the elbows connect to. I think if you route it to the centre of the filter it will then vent to both carbs but may also contaminate the filter itself.

I've just been out to garage and whipped my elbow off to take a pic so you can see where the vent ends up. It's pointing away from the inside of the filter down into the path of air into the elbow that connects to the carb. Mine vents to both sides (this is the left) but you are only going to have the option of the right side.
« Last Edit: October 26, 2014, 03:43:53 AM by bhodgson »
Barry Cheshire, England 79 R45

Offline marcmax

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Re: Crankcase vent
« Reply #4 on: October 26, 2014, 05:34:04 AM »
Thank you for Barry for taking the time to pull your bike apart and take the picture for me. Since installing a fiberglass starter cover/ airbox eliminator I have had a small catch can connected to the crankcase vent. I pull the cover once a month to empty the can and I have yet to get even a thimbleful of oil out of it. Rather than risk contaminating the filter, I will route it into the right carb intake stream. Thanks again for your help.
Keep your bike in good repair: motorcycle boots are not comfortable for walking.

1982 R65ls    1984 R65ls