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Hey y'all, just wanted to post my first thread discussing an issue I finally fixed today.

My 1966 Bonnie had been leaking oil quite a bit for the past couple of weeks. It came out directly below the crankcase/onto the kickstand creating a MUCH larger than normal oil stain on the ground.

Also I heard a louder than usual knocking sound coming from the rockers.

I decided to get to the bottom of this and realized that the chain had been rubbing up on the oil breather tube and created a nice size hole. The breather tube runs from the crankcase and returns blowback into the oil tank as well as the "chain lube" "T".

I didn't think this was that big of a deal, but someone please correct me if I'm wrong. Although the breather and the scavenger lines are separate, the whole oil system works on pressure. I believe that if the breather line has a hole, it is not giving the crankcase enough back pressure which has an effect on the rest of the oil lubrication system. Also I notice there wasn't a healthy flow from the scavenge line back into the oil tank and therefore there wasn't a good flow into the rockers from that same scavenge line.

I was intimidated when I saw the breather tube disappear into the dank depths of the crankcase and thought about possibly patching. After gathering myself I figured if you're gonna do something, do it right.

I purchased 6' of 5/16 ID fuel line from Auto Zone, a pen flashlight, and an extremely long needle nose plier. Then I laid the bike over on it's right side (recommend draining oil, gas, and removing battery) and ripped out the old ratty breather hose. Replacing the hose was easier than I thought... although some four letter words were used. No clamps needed as the spigot is 1/4 ID and the 5/16 ID hose fits snugly over. Then I ran the hose back up and into the "T".

Cranked over the bike and voila! Scavenge pipe was returning a solid flow into the oil tank, rockers running smoother, and if you put your finger into the oil tank where the return breather line goes in you can feel the compression coming in. All is good!

I've seen a lot of threads talking about just leaving the breather tube hanging down and not connecting it back. In my opinion this is not a good idea. Think about it.... when it is connected to the oil tank, the line is located above the crankcase so it HAS to build up pressure/some oil in the crankcase before it can send it up there. If the breather hose just hangs out and drips on the ground there is no resistance and there is nothing to keep oil from blowing out freely from the crankcase resulting in low oil levels and low pressure.

Best not to muck around with this and just to keep it standard. Although I see nothing wrong with turning off the chain lube screw in the oil cap and using regular chain lube.

Hope this helps if anyone has an oil issue.
 
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