Author Topic: oil pumps  (Read 105 times)

Online KiwiGF

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oil pumps
« on: 25.05. 2021 22:17 »
Thank you Bsareg!  I found the CPC brackets online.  They are a brilliant design, and at a reasonable cost.

This almost makes up for the some of the recent setbacks on my project, such as discovering that the original oil pump is completely seized...

It’s not uncommon to find seized pumps if made in mazak, they are fixable at zero cost in most cases given time and patience. It’s good practice to check these pumps rotate freely before running a bike been left standing a while, they might work for a while then strip the gears driving them with horrible results.
New Zealand

1956 A10 Golden Flash (1st finished project)
1949 B31 rigid “400cc” (2nd finished project)
1968 B44 Victor Special (3rd project,in progress)
2001 GL1800 Goldwing, well, the wife likes it
2007 KTM 950 Adventure, cos it’s 100% nuts

Offline Swarfcut

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Re: oil pumps
« Reply #1 on: 26.05. 2021 07:59 »
 Good advice there from Kiwi. Always use caution with a barnfind bike and don't just jump on the kicker. Seized pumps can be dismantled by heating up with a hot air gun or in the oven when SWMBO is away.  The gears and shaft can usually be tapped from the body. Bloated and cracked bodies should be rejected, but if it looks reasonable, well worth playing with. Plenty on the Forum already about the finer aspects of pumps.

 Swarfy.

Offline tomkilde

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Re: oil pumps
« Reply #2 on: 27.05. 2021 15:39 »
Thanks Swarfy.  The pump spins freely if I loosen the four screws on the end plate, but seizes up firmly when I tighten them again.  I've read the threads on how to fix it, but replacement seems the safer bet.  I will be ordering a new SRM oil pump as soon as I recover from the shock of the price.
1958 BSA A10 Super Rocket

Online Rex

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Re: oil pumps
« Reply #3 on: 27.05. 2021 16:14 »
Is the little separate fibre washer in place at the nose of the pump?
Always makes me cringe when I see posts on F-B where someone's showing off his latest barn find, and someone else suggests he "pours in some juice and give it a kick".

Online KiwiGF

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Re: oil pumps
« Reply #4 on: 28.05. 2021 00:41 »
Thanks Swarfy.  The pump spins freely if I loosen the four screws on the end plate, but seizes up firmly when I tighten them again.  I've read the threads on how to fix it, but replacement seems the safer bet.  I will be ordering a new SRM oil pump as soon as I recover from the shock of the price.

On a B44 pump (similar) I found that a tiny bit of corrosion/swelling on the body, under the gears, caused exactly the symptoms you have described, to fix it I measured the width of the gears (the gears next to the plate, the drive end gears were not the cause) and then used wet and dry sandpaper on a piece of glass  to slightly reduce the gear width, by under 002. This fixed it and saved a bundle of $$$ compared to buying a new one.

I have maybe 6 of these pumps, two I have fixed for spares the other 4, I am 99% certain would respond to the same sort of treatment.

To get the extra 35% flow of the srm pump you can just buy a65 gears and fit them in an A10 body, or get a whole a65 pump and fit the a10 drive end into it.

As you can tell I am too mean to buy the SRM  pump!
New Zealand

1956 A10 Golden Flash (1st finished project)
1949 B31 rigid “400cc” (2nd finished project)
1968 B44 Victor Special (3rd project,in progress)
2001 GL1800 Goldwing, well, the wife likes it
2007 KTM 950 Adventure, cos it’s 100% nuts

Offline Swarfcut

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Re: oil pumps
« Reply #5 on: 28.05. 2021 08:26 »
 We're only talking a very small amount of swelling to prevent rotation. A paper gasket under the endplate usually works and gives an idea of the amount of material causing the problem. If its a "bubble" it will show as a high spot in the casting, but this may prove difficult to remedy because of awkward access. A worn end plate will also save the day rather than shortening gears. Not for the purists, but an easy backyard fix. I suppose an aluminium foil gasket and a bit of skill with a modelling knife is also worth a try....

 Swarfy.

Offline edboy

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Re: oil pumps
« Reply #6 on: 28.05. 2021 20:10 »
i have had this fault before and the reason is someones swopped the oil pump gears at some stage. you need to find a drive gear that doesnt bind from another oil pump. they seem to have been crudely manufactured and matched on the bench. bolted together with the drive gear removed the gears should revolve easily.

Online Rex

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Re: oil pumps
« Reply #7 on: 29.05. 2021 08:44 »
Fine grinding paste and a lathe/drill soon sorts out a binding gear.
Velocette even recommended this method many years back. The main thing is to ensure the gears go back in the same places and orientation as they were when the pump was opened up.

Offline muskrat

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Re: oil pumps
« Reply #8 on: 29.05. 2021 09:30 »
Topic split from original.
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'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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