Hello all. I purchased a 72 B50MX yesterday from a very knowledgeable long time BSA owner and all around nice. I had been looking for a while as they are rare near me (Tucson Arizona USA). We had to drive over 800 miles to make this purchase and brought the bike back in the back of a pickup truck firmly strapped down upright.
At the time of purchase the bike was started and rode a very short distance, like up and down a parking lot. No issues then and no oil leaks.
This afternoon we couldn't resist any longer so my helper and I fired it up and rode up and down the block twice, less than a quarter mile total fairly level gorund. After the second trip up the block the bike was spewing oil out of the in frame tank breather. It seemed like it started spewing once the bike stopped moving but I am not absolutely sure on that. Anyway we shut it down immediately and found the source was the oil tank vent tube. Everything I found online points to the in frame oil tank being over full as being the cause of the problem. However as a former Triumph twin owner I know there is a learning curve with British bikes and I want to make sure I don't do something or ignore something that could cause much bigger problems.
Considering the sellers experince with BSAs, probably over 50 years including professional racing, I find it unlikely he over filled the oil tank. Yes it is possible, but unlikely. He did tell me the bike had not been ridden in over 4 years so I assume he did some prep before selling it. So are there other causes for oil to spew out the in frame oil tank breather? No oil is coming out of the engine breather. Could the long journey in the truck contributed to the oil spewing?
The oil tank does not have a dip stick. The cap appears to have a boss in the underside with with a round hole in it, not all the way through. I am assuming this is for a dip stick. I have a machine shop here so making a new dip stick isn't an issue but I would need to know the over all length and the distance from the bottom of the stick or from the cap boss for the full mark. Can anyne help me with that information?
My goal is to proceed with caution as I climb the learning curve from complete ignorance.
Any help is greatly appreciated.
Dave