Baffled, confused and covered in oil!!!!!!

[KiwiGF]

G'day JulianS & bb.
Thanks for putting my "random thought" to bed. I learn something every day.
Cheers

Here is a good thread on the A65 and A10 oil pump differences, and the worm gear differences, I see Julians statement above the pump rotates the same way as the A10 so this really does my head in 

Possibly going off topic here tho 

https://www.a7a10.net/forum/index.php?topic=5829.msg92030#msg92030

[ironhead]

Hi.
Iv'e been following this post with interest & don't think Iv'e seen mentioned the anti- siphon ball & spring & cap screw thats fitted from the inside of the crankcase.  Is It there?  If not, this could explain a massive over feed of oil. The engine won't seize as the crankshaft will have plenty of "splash' lube. 
Just a thought.

[bikerboy]

Yes its there, it still wet sumps mind but for the minute I have fitted a tap in the oil line to avoid that happening while I sort this problem out. I have prodded that from the oil pump end in case the spring had broken or something else bizzare and its in there and springing back even if its not much of a seal. I would do the A65 type mod if I knew how long the spring should be but I have never seen anybody that knows for sure so will not risk starving the crank of oil by guessing at a spring length.

I did have an anti wet sumping valve in but suspected that might be effecting it so temporarily I fitted a standard tap, if I manage to fix the problem I will invest in one of those taps that stops it starting if its not switched on but I am not willing to spend another £50 on it yet in case I do decide to set the damned thing alight :)

[ironhead]

Maybe time to 'bite the bullet'  & strip the cases to check the pick-up tube as others have suggested. You seem to have covered
 & re-covered everything else in the oil system.  You've mentioned a couple of times there was too much oil in the sump when drained after a ride but have a healthy return flow. ( How much ? 1/2 liter , 1 liter? ) Tends to indicate the sump is filling to a higher level than its supposed to.

[RDfella]

This posting now runs to 6 pages with a member tearing his hair out trying to diagnose a BSA A series lubrication problem. And how many similar posts have there been? Wasn’t that long ago I was in a similar situation with my own GF (for the 2nd time). I just don’t get why this model’s lubrication system should be so uniquely unreliable. The singles aren’t, nor indeed any other engine I can recall – and I’ve worked on a few over the last 55+yrs – and a wide range too. Only failure I remember was on a TE20 Ferguson, where the oil pump gear fell off. Stupid design, a gear of around 3” dia just pressed onto the pump’s ½” shaft. Next one I pinned and it’s still going 50yrs later. Certainly takes the shine off owning a BSA twin.

[bikerboy]

You've mentioned a couple of times there was too much oil in the sump when drained after a ride

Thats only been after leaving it a while I have never ridden it let it cool and then taken the sump off its always been a few days/weeks later

[chaterlea25]

Hi bikerboy,

I would do the A65 type mod if I knew how long the spring should be but I have never seen anybody that knows for sure so will not risk starving the crank of oil by guessing at a spring length.

I posted the information and photos of the mod a while ago

https://www.a7a10.net/forum/index.php?topic=13668.msg111568;topicseen#msg111568

John

[bikerboy]

John

Thanks very much for that info if I have to strip the cases down I will do that for sure :)

[berger]

john very good!! the berger build is getting the conversion as well as an oil drilling for a pressure gauge, it might end up with a dashboard like a mk1 capri gtlxr

[groily]

. . . . one tip I sometimes use

Bend the pushrod comb so that it comes down to sit on the top fin of the cylinder head. Use one of those spring steel chassis clips to slide over the fin and the comb holding it nicely in place.

Thought I'd try this, modded a comb so it could be clamped firmly to the top fin on LH side of head - and the whole caboodle went on first time, no messing. Easiest ever reassembly.
Will find out if it works twice when I check-tighten the head  in a bit  . . . !
So - a very good tip - thanks!

[bikerboy]

You are very welcome 

[BSAmoto]

When the return is too slow and engine fills up and blows the oil through the breather, remove the sump plate. Push a rubber hose over the pick-up tube and insert your airgun. When blowing air into this contraption look and hear for leaks. Check that the ball is free moving and has still its upper stop in the pick-up tube - otherwise it might seal the tube enough to reduce/stop the return. The possible outside leak is the aluminium pin that is inserted into the return bore right above the frame tube, the inside leaks can only be at the oilpump gasket or where the pick-up tube is inserted into the crankcase or the tube is cracked somewhere, allowing air to be sucked instead of oil. If this is all good, there is only a damaged return pump or a problem in the hose or tube and connector going into the oiltank.
cheers

[Rocket Racer]

This engine sounds like it is wet sumping when in use, when the pump is running. Not a leaving it standing issue. Ball valves will cure a parked non running wet sump but an engine that is pumping oil both ways should by definition return more than it feeds. So the scavenge balance is compromised, could be anywhere from the rocker feed taking all the return (if lines obstructed), or a leak in the scavenge pipe or loose pump. Its not PRV or pressure related, any excess oil in a crank will end up blowing out the breather, nothing to do with crankcase pressure or breather timing. Presumably you're not running a return filter which can obstruct the return feed.

[bikerboy]

BSAmoto

Great idea when I get around to looking at the plunger again I will do exactly that thank you.

Rocket Racer

Thanks for the input and altho I know the pipes are clear yours are good observations

[stev60]

Watching this  thread,  there are a lot more capable of giving advice than me, a question after a run and giving bike an hour to drain, how much oil would be expected to drain from sump, Ive  got 100mm after a run, give a few days its more ,  which I allow for and drain again or run, 51 A7, just lets the oil  go down