SRM oil pump - yes or no

[David Tinsley]

I put one in mine when I rebuilt the engine just make sure the pump has been primed before starting, SRM recommend using the kick start but it was easier on my knees to do it with a speed wrench before I put the head on .
I had an air lock in the line on  suction side of the pump had to tilt the motor a bit on the stand to release it .
heading to Wales next week , you wont regret your decision if you dont tell the wife how much it cost .

Thanks for the tip with the head off and speed wrench, I will do that. The " boss" is OK with me spending money on the bike, about the only thing I spend money on. It is a chunk of change though and I got the PRV on order as well!

[JulianS]

When fitting the pump I leave the pump to crankcase screws sligthly loose, connect the oil pipes and allow the oil to seep from the joint, when that happens any airlock has been removed. Tighten the fixings, check for oil return on the kickstart then replace the outer timing cover. Saves all the frantic kicking to try to break the airlock.

With an end feed crank engine oil will emerge from the oil pipe in the inner cover in a few kicks.

[Swarfcut]

 An alternative new pump is the Cast Iron bodied version marketed by Wassell/Hepolite.  BSA switched to a cast body later on for the A65, and so this mirrors later development.

 Taking a chance, a good output pump can be built up with A65 body and its larger capacity gears, along with the A10 nose and drive spindle.

 Purists may wince, but unless you are spending big time on an almost every part new rebuild, in my world the cost of a new SRM pump cannot be justified for the low mileage my bike covers.

 Swarfy.

[Colsbeeza]

Dave, A yes from me too. I stripped and faced the old pump, but the body was a bit distorted and evidence of Mazak cracking up. There is no guarantee that an SRM pump will stop wet-sumping, but a good anti-drain ball seat will. I refitted the anti-drain ball valve in the crankcase, lapped in a ball (araldited to the end of a thin hollow tube), tapped a new ball to get a good seat (use a proper hardened punch) and fitted a third new ball and a spring approx double the force of a standard BSA spring (I have the data for the spring). When running, it idled cold at 60psig, hot at 50mph at 20psig and about zero psi at hot idle. (I have a pressure gauge). I don't think that zero hot idle alone is a big worry as the crankshaft centrifugal force ensures some pressure within the bigend. Old advice was not to worry - no gauge no worries!! I was not confident with the old pump, so then fitted an SRM pump and PRV. I bolted on the SRM pump without gasket and used a 1.5 thou feeler gauge to look for any gaps between the pump and mounting base, and made sure there would be a good gasket seal. It now idles cold at 60psig, runs hot at 35 psig at 50mph and idles hot (very) at 15 psig. I use Penrite 20W-60 with added zinc and run a Norton-type spin-on oil filter. Very happy with all that. The other advantage of an SRM pump is you don't need a special gasket (washer?) under the small end of the pump - use the SRM gasket.
If you still have the crankcases separated, lay the RHS crankcase down horizontal with oil entry hole upright. I filled the oil entry hole with oils of several viscosities to see how long it took for the oil level to drop. Finished with diesel fuel and no leakage at all. Now it does not wet sump at all, even after several months of no riding.
Another tip given to me by Richard Orabanda was to immerse the crankcase half under water and inject compressed air into the oil gallery to check that there are no leaks around the outside of the Timing side bush. After that ramble I am off for a couple of beers - been hot here over the past few days.
Col

[Catz]

After reading all the positive comments, i've just shelled out. 
After yesterdays ride to a BSAOC meeting made me think how much i like riding the old A10 and would like to continue without that nagging feeling of impending doom.

[Rex]

Makes you wonder how these old bikes have travelled all those miles day-in day-out without self-destructing.

[Triton Thrasher]

Makes you wonder how these old bikes have travelled all those miles day-in day-out without self-destructing.

Keep it travelling day-in etc. and the oil won’t end up in the crankcase.

[Sakura]

Makes you wonder how these old bikes have travelled all those miles day-in day-out without self-destructing.

Oh they did, they did. Frequently! Knocked out main bushes, rods through crankcases etc. But then, no-one with half a brain revs the guts out of them like we did then. They weren't cherished classics then, just bikes for leary boys.  😀

[Rex]

Keep it travelling day-in etc. and the oil won’t end up in the crankcase.

Of course, but then oil draining down isn't the prime consideration when contemplating buying a new pump.

[Swarfcut]

 Often overlooked, it does not matter how good the pump is......if the PRV is blowing off at a low pressure all the expense is in vain. So add a new ball and spring at the very least.

 But keeping in mind the amount of oil mist flying around, there is almost a belt and braces approach to the lubrication system and the survival rate for bikes treated gently is probably more down to this, even with a weaker pump. The killer, of course, is that crankshaft design with a timing bush subject to wear and leakage, along with the ever crap collecting blocker to the drive side big end.

 No excuses, no if's or but's. Make it your first job of any engine renovation. The rest is easy.

 Swarfy.

[Triton Thrasher]

Keep it travelling day-in etc. and the oil won’t end up in the crankcase.

Of course, but then oil draining down isn't the prime consideration when contemplating buying a new pump.

Yes it is, according to contributors above.

[Rex]

Is it? Most (understandably) seem more concerned about having a new reliable pump to go with their expensive engine rebuild.

[Catz]

Just fired the old A10 up, not been up the road yet, and one thing i've noticed with the new SRM oil pump is that the oil return back to the oil tank is now like a stream instead of a bit of a trickle.
I reckon that's a result.

[muskrat]

G'day Fellas.
With the plunger rebuild I wanted to see oil circulating straight away. I primed the crankcase with a cup of oil and used a clear hose from the engine to the oil filter. It didn't take 1 second to show flow and about 20 seconds to show bubbles. At the tank the spits and spurts are almost a continuous stream.
Cheers

[Colsbeeza]

Catz, Success. But be aware that as the scavenge side of the pump has greater capacity than the supply side, that bubbles should occur as soon as the sump has pumped out. Mine takes about 5 seconds as mine doesn't wet-sump.