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

[Swarfcut]

BB...Here's me thinking you know nothing about these motors... turns out you are well experienced and with what looks like a choice when it comes to replacement parts. Apologies if I have stated the obvious, but it is always difficult to know what knowledge, experience and skills the fella with the problem has. Looks as if despite your engine building skill, it has defeated you (and a good few others) for the time being.

 Stick with the KiWi....a re visit of the oil lines and tank is quick and easy.....a good pressure on the return side of the pump would indicate  reasonable pick up and a good pump.



KiWi....Working OK without the pipe is possible on the S/A engine, the oilway is just above sump plate level. The plunger pipe works its way from the sump, hugging the inner crankcase wall, so the oil would need to be up to the main bearing bush, and higher, by which time all the oil is out of the tank and being spread over the road.

 Swarfy.

[bikerboy]

Swarfy

No problem got my first A10 (and still got it) back in 1972 when I was 16 and have had so many to bits over the years I have lost count :)

But as you know that does not mean somebody has all the answers nor does it mean that sometimes we overlook the obvious so I am always grateful for advice particularly as some people on this forum make me look like a total newbie with their technical knowledge.

I would still pit myself against anybody at fitting the rocker box tho, I definitely have that down to a fine art and can fit one in minutes :)

Probably because of the amount of times I have messed up a rebuild and needed to have the rocker box on and off 150 times lol

[Minto]

“”I would still pit myself against anybody at fitting the rocker box tho, I definitely have that down to a fine art and can fit one in minutes””

If you fancy posting some tips on this subject, or a “how to” video, I would not be offended!!!

[Gerry]

Hi Minto, If I were to pay your fare to Adelaide Australia plus accomodation and meals due you think you would be able to fit my rocker box on my 59 A10......:-) Cheers Gerry

[Minto]

Hey Gerry
That sounds great, I’ll pack my case later. I’ll see if I can talk BikerBoy into coming as well, he can show us both how it’s done. 👍😁

[paulmbsa]

I had the same problem turned out to be the pressure release valve makes no sence but changed it and hey presto

[RDfella]

Of all the different engines I've worked on in the last 55 + years, from lawnmowers to race cars plus marine, I've never come across an engine model with more oil issues (most of which are plain weird) than the A series. The singles use a similar system without problems, so why are the twins less reliable lubrication-wise than the weather? And let's not pretend that isn't the case, as the posts on this forum prove otherwise.

[ironhead]

Of all the different engines I've worked on in the last 55 + years, from lawnmowers to race cars plus marine, I've never come across an engine model with more oil issues (most of which are plain weird) than the A series. The singles use a similar system without problems, so why are the twins less reliable lubrication-wise than the weather? And let's not pretend that isn't the case, as the posts on this forum prove otherwise.

I recon you can point the finger directly at the R/H main bush  with oil trying to be forced through a rotating shaft with a small hole drilled in it. Most other reliable systems have a centre fed crank. Once the crank starts spinning it acts like a centrifugal pump in itself. maybe if BSA had fitted a pump with twice the volume it may have worked properly (eg auto crank & pump style). Other engines with Right hand main bush oil systems suffer as well, one that comes to mind are the AMC singles. ( try finding one without a shot bigend bearing). the difference between these & BSA singles are chalk & cheese, yet they both use roller bearings, in fact at a quick glance the AMC looks beefier.

[bikerboy]

Minto

I can give you 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. Make sure its one of the inlet pushrods that is high so the two exhaust rods are at at the same height.

Loosen the adjuster nuts on the tappets but do not slacken the actually tappets at all. Slip the box on and all those little rods will drop straight into those cups perfectly every time

[bikerboy]

Well so far no joy. Oil pipes off and all clear, return to the tank clear as a bell.

Sump off and there was too much oil in there but as the pump is tried and tested a bit confused as to why.

Scavenge pipe not blocked in any way (no magnetic bolt on it)

The only parts on this bike I have not run relatively recently are the crankcases so to me I am still thinking scavenge pipe but god knows why.

[Swarfcut]

   As an indication of the oil return, try a transparent plastic pipe fitted onto the scavenge pipe dipped into oil in an oil drain pan under the open sump. A bit messy, but shows the relative balance between feed and return.  Poor pick up is a combination of obstruction, air leaks, poor seal between pump and crankcase, or just a poorly performing pump.

  Here look for a  worn, cracked body, sheared off  drive tab on scavenge gear, really badly worn or loose end plate.  Not all or any may apply to your pump. Long shot, but substituting another pump would be well worth another try before  a full strip down to change the cases.
 The PRV is an enigma, as open or shut the total volume of oil delivered is the same, whether blown off or fed under pressure to the crank bush and bearings. But experience would indicate changing the PRV can sometimes effect a cure for mysterious oil problems.

 Swarfy.

[Rex]

On Tr*umph twins it's possible to test the scavenge pipe by slipping a piece of tubing over the scavenge pipe and gently sucking while blocking the oilway on the engine with your thumb.
It's a good definitive test of the pipe, so maybe it could be used here too?

[bikerboy]

Well I have changed everything except the PRV which looks fine.

Oil circulates perfectly but its still throwing it out of the breather when it does more than about 15 miles

Looks like another strip down after swapping the PRV with one of my working A10's which I dont think will cure it

[edboy]

i would say the prv is very important and worth a good examine of the ball and seat. if the ball doesnt seat after the oil warms [ spring ] oil will be dumped into your crankcase and out the breather. it will ruin your big ends quickly as  they lose oil pressure.

[berger]

I once found a nasty split in a BSA prv where the ball seats. I was looking to use one on the beezer until I thought sod it your messing with the engines heart and bought srm pump and prv. I had a few and even converted one when I wanted to play about with something to test oil pressure before and after relief to cam etc. The springs and seat can never be as good as when they left the factory I couldn't believe a hard ball bearing could have such a wear mark in it but then again its getting attacked by all sorts of impurities , after all i'me bu**ered at 60  and some of them are even older than me, the pump and prv should be pensioned off unless put to a test and proven to be able to provide a good service