mystery of wet sumping (bsa a10)

[dicky-yrrep]

I have asked this question before but i have never received a straightforward answer, So, in simple terms, If you leave a BSA A10 in a garage for say 3 months without kicking it over and it wet sumps as they do,
When you kick it over for the first time does the oil in the sump return to the oil tank or does it stay in the sump    

[Revband]

After three Months if the oil pump is worn, which it almost certainly is then a lot of oil will be down there, the oil pump is bigger on the return side than the feed side so eventually the oil will be returned to the tank, while this is happening it will be getting thrown around by the flywheels and up the pistons where it will burn and create a lot of smoke, also it will probably be pushed out of the engine breather and make a mess on the bike and the ground.

Anti wet sump vales are fitted to this engine but in BSA's infinite wisdom you have to split the cases to get to it, an easy answer if you regularly leave the bike for long periods is to fit an after-market valve in the oil feed pipe these are available BSA specific which screw straight into the crankcase in place of the original adaptor, failing that drain the cases before starting or put up with the smoke and mess.

[bikerbob]

Hi there Three months is along time to leave an A10 without running it. My recently sold A10 if you started it up every 2 weeks there was no problem leave it 4 weeks and it would start but you would get quite a bit of blue smoke for a couple of minutes but leave it 6 weeks and as well as the blue smoke you would end up with quite a bit of oil on the garage floorwhich came out of the crankcase breather. But not all A10's are the same some will be worse than others regards the anti drain valves some people like them and others would not touch them. I preferred to start the bike every 2 weeks while it was off the road over the winter months.

[Revband]

Hi Bikerbob

I fully understand your concern regarding the valve, as you say some do and some don't, I have them fitted to three BSA's and have had them on for quite some time without any problem, I have yet to meet anyone who has fitted one and then removed it again, but have met a lot of people who cry them down but have never tried one, this style of anti drain valve was fitted to Velocette singles from new, always a personal choice of course.

[Goldy]

Hi dicky-yrrep. It's not wise to start the engine with a large amount of oil in the sump.  another option is to modify or replace the sump plate with one which has a drain plug. It is then simply a matter of removing the plug to drain the excess oil before starting up.