OK, here is an update on my leaky '70 Commando. I'm just now getting back to it, as I have several other vintage machines that have required my attention (including an AC system rework in my '72 Firebird that, with the onset of the Texas summer, had to take priority). She's blowing 34 degrees F out the vents now.
Back to the Norton. From my original post, here's a list of work I have completed to date. I want to point out that I do very meticulous work, keep a very neat and organized work area (I've overhauled automatic transmissions here -- requires almost surgical cleanliness), and spend WAY more time on each task than is necessary. Old retired guys like me have that luxury!
* Dry primary with belt drive from CNW. New primary cover O-ring gasket.
* PCV conversion from JS Motorsport using the drain plug reed valve and plugging the OEM disc valve outlet
* Plugged the chain lube drip tube
* Replaced (seeping) rocker box gaskets; now dry
* Replaced (leaking) kickstart O-ring and shifter shaft seal; now dry
* Replaced (leaking) tach drive base gasket; now dry
* Pulled oil tank, cleaned it completely, and let it sit overnight filled with fluid covering all connections and fittings. It was completely dry externally the following morning. I found no evidence of a static fluid leak on the bench. Saw no seepage when I pressurized it a bit with compressed air. I did hear it “oil can” a bit when I did this. I saw no evidence of damage, however.
* Cleaned engine externally as best as possible to remove as much residual oil as I could.
* Used compressed air to verify all ports in and out of the oil tank were clear.
* Drained the engine of oil as best I could. I kicked it over repeatedly to get oil to come out the return hose to the tank.
* Replaced the tank and filled it with exactly two quarts of oil (my bike has no oil filter) in an attempt to minimize blow-by.
* Ran the vent tube that originally went from the OEM disc PCV valve to the oil tank and ran it from the oil tank into a catch bottle to verify minimal or no tank pressurization on the road. The bottle is basically dry inside after about 50 miles.
Since I first posted, I have also installed a tach drive housing with a spring-loaded rubber lip seal instead of an O-ring. This immediately stopped the oil spray onto the bottom and right side of the front of the engine.
It also seems my newly-replaced X-ring seal on the kick start shaft has started seeping again, but not enough to cause the problem(s) I'm seeing. It may also be that oil from the leak(s) in front of or over it had pooled there and was still running off.
I added UV dye to the oil. Before I started it or test rode it to see if new fluorescent oil was leaking, I shined the UV light on the current leaks and noted all that oil glowed, too. So, as previously suggested here, I am going to degrease the whole thing to get a fresh start. That will be a big, messy job.
However, I did note that a large amount of oil was puddled under the oil tank. Given that this area is protected in the front by the air cleaner and underneath by the panel it sits on, I can only surmise that a large portion of the leak(s) is coming down from the tank itself. To that end, I currently have the tank off again and am giving it a VERY close inspection for leaks/cracks. Once I assure myself that it does not leak (static and under a little pressure from an air hose), I will degrease everything, take it for a ride, and start this whole frustrating process again. Fun.
