BSA Owners' Club Forum

The BSA Workshop => Singles => Topic started by: BOBLAN on 08 February, 2017, 12:46:08

Title: B31 Oil return
Post by: BOBLAN on 08 February, 2017, 12:46:08
Hi all

I am in the process of recommissioning a 1946 B31, which has been off the road for the last 25 years. I understand that the engine was rebuilt prior to it being stored, so I was hoping that all is well with it. I am currently changing all the oils and would appreciate any help with the following query:

I have emptied the old engine oil from the tank, cleaned it out and replaced the filter which was damaged. I have taken the sump bolt out to empty any old oil, and removed the bottom cover plate to clean the gauze filter. I have also checked that pressure ball valve is free of its seat.

On refilling the oil tank and removing the spark plug, I was hoping that I would see oil returning to the tank when kicking the engine over fairly fast. However, I cannot see any movement in the oil, so I am worried that the oil may not be circulating? Or perhaps it will only return when the engine is actually running?

I would appreciate any thoughts.
Title: Re: B31 Oil return
Post by: JulianS on 08 February, 2017, 13:11:22
It will return on the kickstart but might take a lot of kicks.

Suggest you check oil is reaching the engine by undoing the feed pipe at engine end.

If thats OK its a good idea to prime the pump by introducing some oil into the sump. A good 200ml or more is what I use on my A10. Unless you prime the pump then it will take a while to get oil there from the feed side of pump before it can return.  You should be able to prime by removing the tappet cover at base of cylinder and squirting oil in there and allowing it to drain into the sump.
Title: Re: B31 Oil return
Post by: ANDY HIGHAM on 08 February, 2017, 16:22:33
I have just rebuilt my B31 engine.
After filling the oil tank I loosened the oil feed pipe at the engine until new clean oil dripped out and re tightened. I then removed the ball valve in the timing cover and kicked it over a few times until oil flowed from the hole and then replaced the ball valve.
This ensured I had oil all the way from the tank to the end of the crank.
Title: Re: B31 Oil return
Post by: GLENN on 08 February, 2017, 20:48:23
Hi Andy,

After a prolonged period of storge I would also recommend removing the oil pump and checking if it's tightened up as is so often the case with the B and M series engines.  The bike will run with a tight pump, but no doubt will cause damage in the long run. 

Title: Re: B31 Oil return
Post by: ANDY HIGHAM on 08 February, 2017, 21:10:12
My engine has just been assembled with a new ABSAF high volume oil pump. Made out of real aluminium instead of monkey metal
Title: Re: B31 Oil return
Post by: BOBLAN on 09 February, 2017, 17:55:02
Many thanks for all the replies, I did as each suggested and got a  result! So yes, I must basically remember to prime the pump next time...

Even got the engine running for a few minutes, but need to now stop the petrol pouring out of the carb...

Thanks again