BSA B31 Can't tighten up the oil pump

Started by DGBland, 25 November, 2023, 16:28:19

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DGBland

I have started the rebuild on my B31 and I can't tighten the oil pump up without it nipping up against the worm drive shaft. It says in the manual to not to overtighten it in case it nips up but I can hardly tighten it up at all. I assume this will affect the effectiveness of the pump.
Is there a fix for this?
Thanks
David

Roy

That's very typical of that type of pump , the maisak pump body  distorts and pinches the pump gears ,to put is bluntly old pumps are a nightmare,and if/ when they are tighten and pinching the screw on the crank pinion gear and the upright spindle will strip and you then have no pump ,it's most likely all the old pumps you see on auction site have been taken out for a reason ,the gears and counter bore could be relived but if to much is taken out the pump is next to useless, best suggestion is to buy /save up for a new hepolite brand pump supplied by wassells
I have fitted and used dozens of these for road and race , with no trouble at ALL. Super steel body pump ,

Pete Gill

Quote from: Roy on 25 November, 2023, 17:44:55
That's very typical of that type of pump , the maisak pump body  distorts and pinches the pump gears ,to put is bluntly old pumps are a nightmare,and if/ when they are tighten and pinching the screw on the crank pinion gear and the upright spindle will strip and you then have no pump ,it's most likely all the old pumps you see on auction site have been taken out for a reason ,the gears and counter bore could be relived but if to much is taken out the pump is next to useless, best suggestion is to buy /save up for a new hepolite brand pump supplied by wassells
I have fitted and used dozens of these for road and race , with no trouble at ALL. Super steel body pump ,

I agree i spent ages trying to free up my B31 oil pump, changed body on it even but was still tight on refitting. Paid for a new pump as suggested above - expensive though- but the engine needs oil- there's a reason why its always the first thing in the owners manual.

Pete C

take a look at the WM20 website info  http://www.wdbsa.nl/Oil%20Pump.html

with a little (lot!) of patience you can most likely get the pump to fit and work OK.