Author Topic: 'Orrible oil pump  (Read 261 times)

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Online chaterlea25

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'Orrible oil pump
« on: December 28, 2018, 11:48:33 pm »
Hi All,
I found this picture of a BSA single oil pump on ebay
It shows how the mazac alloy can and does rot and crumble away
If you oil pump looks like this, its time to look for a better or new one  ::)

John

Online Owen

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Re: 'Orrible oil pump
« Reply #1 on: December 29, 2018, 07:02:43 am »
It's funny that the oil pumps will do that, yet the amal carb bodies which are the same material don't tend to go that bad. Yes the do suffer from creep, but can come up quite good with a good scrub.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Offline timsdad

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Re: 'Orrible oil pump
« Reply #2 on: December 29, 2018, 08:15:47 am »
I think oil pumps suffer the most when the bike is stood up with nasty old oil in it. All the acids, sulphur and the like drift down to the bottom and eat into the oil pump's body when it's dormant. If the oil is changed, and engine fired up for a minute or so to circulate the new oil before hibernation, then the oil pump would probably be as right as rain.

Carbs just evaporate and dry out, leaving a bit of crap to block the jets.


Ray
Just a motorcyclist.

Offline stev60

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Re: 'Orrible oil pump
« Reply #3 on: December 31, 2018, 07:53:27 pm »
I wonder just what material BSA used to make those pumps, its like they searched hi and low to find the crappiest material they could, then in the manual go to great lengths to warn anyone from going near them, when they are probably one of the more simple bits to work on. its like they are made of some cheap die cast porous material

Online Tman

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Re: 'Orrible oil pump
« Reply #4 on: December 31, 2018, 11:20:40 pm »
According to a metallurgist on the A7/10 form you couldn't be further from the truth. Apparently it's far from "crappy" or "porous" but actually an ideal material for an oil pump, and that's why it's still used now 45 years on from BSA going belly-up.
If he agrees I'll copy and paste his extensive and informative posting on here.

Offline stev60

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Re: 'Orrible oil pump
« Reply #5 on: January 01, 2019, 01:15:29 am »
I would be really interested to see it, four pumps that I have had apart are all showing signs of a porous condition, possibly caused by years of oil corrosion, is the pump in the A7 and 10 the same , ive had the pump out of my A7 and that looked fine

Offline timsdad

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Re: 'Orrible oil pump
« Reply #6 on: January 01, 2019, 08:43:53 am »
When they were designing and building these old bikes, they could never have foreseen that folk would be playing with them, and whinging about them, eighty years later. BSA oil pump problems are only caused by lack of use coupled with the additives and crap added to oil after the pumps were made and then owners not taking proper care of them.

Try putting a Honda or Hardly Driveable oil pump in a bit of oily vinegar for a few years and see how it fares. In well over fifty years of messing about with these old bikes, I have never thought these Mazak pumps were a major problem, any more than Amal carbs are.


Ray
Just a motorcyclist.

Online Owen

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Re: 'Orrible oil pump
« Reply #7 on: January 01, 2019, 08:58:36 am »
This is another one of those subjects that has been blown out of proportion rather than take the facts as they are. Yes they do have there problems, but can usually be fettled to get going again given a little time and patients.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Offline timsdad

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Re: 'Orrible oil pump
« Reply #8 on: January 01, 2019, 02:14:51 pm »
All part of the fun, apparently, Owen.

Life is just a series of problem-solving and BSA oil pumps are just the very smallest of problems!


Ray
Just a motorcyclist.

Online Owen

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Re: 'Orrible oil pump
« Reply #9 on: January 01, 2019, 02:30:08 pm »
Like everything nowadays, its the basic things that are being lost into the black arts. Hopefully this site will preserve them for future generations.
1940 C12 (350cc)
1945 C10 & C11
1953 C10 & C11
Anyone want a B20 in need of a lot of tlc

Online Tman

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Re: 'Orrible oil pump
« Reply #10 on: January 07, 2019, 11:03:00 am »
As promised-

Over the last 30 years I have accumulated a few A10's.

I have had two of the original (Mazak) housings fail (crack and break away) in the thinner drive spindle area.

Others have shown signs of the metal crumbling away.

Not surprising that a 70 year old material,that was specified more for cost saving, than metallurgical quality (ie material was cheap), suffers fatigue failure.

I work in the fluid power industry; the only application of this material in a gear pump I have ever seen, is by now defunct manufacturers of British motorcycles.

All of my machines have a replacement high quality pump: some SRM, some cast iron).

Richard

Reply-

Total & utter crap.
The zinc based alloys used were metallurgically  a very sound decision.
The EXACT SAME ALLOY has been used for decades in carbs, injection pumps & turbos.
Even today the tonnage of Zn based alloys is nearly 2/3 the tonnage of Aluminium/\.
Mazark by the way is a trade name for around 20 different zinc based casting alloys, and not a specific metal.
It is the perfect material for pressure tight cast to size high precision castings and is still used for that purpose today.

The simple fact is BSA did not factor in a 70 year service life. THIS IS NOT A MATERIALS FAILURE .
Your A 10's had a 90 day warranty in the USA and 12 months in Australia so the minimum service life of any part was the 12 month warranty period.

BSA knew what the average service life of a motorcycle was back then ( around 25 years from memory ) and so they designed the bikes to go that distance.
Remember that in the day it was new rings & big ends at 30,000 miles for BSA's but 50,000 miles for Triumphs because they used better slipper materials.
However no one puts Schit on the slipper material.

And by the way, MAZARK was not cheap. It was a branded alloy so BSA had to pay royaltities for using it.
It was however easier to machine and suffered substantially fewer machining failures than making them from cast iron.
So if you consider using a material that had a better than 90% acceptance rate over one that had a 30% quality failure rate then yes it was a cheaper option than the cast iron pump.

Oh and by the way just about every automotive oil pump, the one in your car right now is made from the same
DEFECTIVE CHEAP & METALLURGICALLY UNSUITABLE MATERIAL
so you better go out right now rip it out and toss it  in the scrap bin.