In search of reliable B25 oil pressure.

[HPbyStan]

Despite an early problem with lathe cut threads which was cured by running a die over them, this thing is a nice piece of work that should totally cure the '67-'70 B25 oiling problem. Good on ya mate.

[hwan]

After the dramatic drop off in oil pressure with my 'newly' rebuilt engine and cancellation of this weekends Enduro - i think i'll pay more attention to the oil-pressure valve as well ....

Any chance of 'pinning' this thread to the HP Stans reply, please ?

Edit by MM: Done, see above.

[jbmccandless]

Subscribed. In case another run of these valves is done, I'd be interested in one for my 67 B25.

After a seizure, I just found my oil pressure relief vale was missing the ball entirely. Maybe this caused the seized piston and the bottom end knock.

Looking for all oiling advantages for my rebuild...

-Jason

[minetymenace]

Bit of forum maintenance:

jbmccandless and lathejack, would you update your profiles please and let everyone know roughly where on the planet you are?

bit of oil gadget coveting:
lathejack, got any more PR valves going begging?

[jbmccandless]

Got it, updated. Thanks!

[lathejack]

Yes I have a few more relief valves almost finished, with another larger batch planned.

Also have other BSA related items on the go, such as a small batch of new lozenge silencers, side stands and the small front chain guard. Maybe also some of the small and large silencer heat shields.

So along with my day job, domestic duties and working on the B50 my time is spread quite thinly. But it's all good fun here in my small portion of Small Heath production.

[jbmccandless]

Yes I have a few more relief valves almost finished, with another larger batch planned.

Glad to hear that lathejack, I'll send a private msg to get on the waitlist. No rush on my end,

Best, Jason

[B44Claus]

Hi Lathejack,

Any chance that you still have a few of your improved pressure relief valves in stock?

I'm rebuilding my 69 starfire engine and would like to avoid big end disasters.

Brgds,
Claus

[lathejack]

Hi Lathejack,

Any chance that you still have a few of your improved pressure relief valves in stock?

I'm rebuilding my 69 starfire engine and would like to avoid big end disasters.

Brgds,
Claus

Hello Claus.

Yes, I have just one pressure relief valve left at the moment. The latest ones have a redesigned outer cover made from alluminium alloy, with a short boss on the end for fitting a lockwire if required.

Sorry for the delay in replying, I have only just found your message.

[B44Claus]

Hi Lathejack,

PM send.

Brgds,
Claus-Bo

[webby16]

Very interesting do you have any left for sale?
Thanks David

[lathejack]

Very interesting do you have any left for sale?
Thanks David

I don't have any left at the moment, just posted the last one off to Denmark.
I have stocked up on materials, and will be making another batch as soon as possible. I'll let you know when some more are available.

[minetymenace]

Bump! Its raining, how about some spinning something up in the shed?

[Blakey]

Hi,

Im very new here with a 68 B25 in pieces.

Are you still making your super douper relief valves?

I suspect the demise of the motor could be due to low oil pressure.

Cheers
Ian

[minetymenace]

To the forum Blakey.

Would you update your profile and let everyone know roughly where in the world you are please?

Low oil pressure on a B25 could be the pressure relief valve, but is more likely to be the end feed quill not sealing (for a number of reasons), big end failure due to lack of oil changes (or some other cause) or a knackered oil pump. The low oil pressure light is for deaf people to tell them when the big end is shot. The pressure switch is one of the truly unreliable thing about these bikes. I think your engine's demise was probably the cause of the low oil pressure rather than the other way round.

But yes, I too would like a new relief valve or two!

[Blakey]

Profile updated.

Initial failure was top end.
Now rebored.
looks like a previous seize. no play on the big end.

Now the confusing bit.

Oil is constantly draining back through the scavenge valve. I've reseated the drain back valve by giving it a couple of taps. Im thinking that the relief valve may be knackered?
Lots of signs of poor maintenance. Soooo.......
I have decided to strip the engine completely and check everything. I am a complete novice to this so Ill be asking lots of daft questions!

[kommando]

New ball and spring are mandatory every time you maintain that non return valve, the ball gets a set for the seat and the seat distorts and spring loses tension. Even with a new ball, tapping it onto the seat and new spring will not fully work but at least slows it down. The relief valve is after the non return so bad or good has no effect on the static wet sumping only the running oil pressure.

[Blakey]

Ah.

I was misunderstanding the lubrication and scavenge schematics I was looking at.

So the oil draining from the scavenge non return valve [which is obviously not doing its job] is coming from the anti drain valve which is not doing its job?

[kommando]

The scavenge non return in the sump drain only holds back the oil in the pipe, nothing more and just keeps the pump scavenge gears full of oil, the feedside non return in the inner timing cover stops the oil tank contents from draining into the engine when it not running.

[Blakey]

Got it thanks.

[Blakey]

Ok. Scratching my head now.
Oil is still draining out of the scavenge valve. I've had a drip tray underneath and it's slowly but surely filling up. Bout 500ml do far. Surely can't be that much oil in the pipe?
Also found some later cases and thinking of rebuilding around them. Any pitfalls? Any nastys to look for on the cases?

[kommando]

What is the oil level in the frame, if its too high and has reached the return pipe outlet then it will siphon the excess oil out. Or someone has added a longer tube to G to stop the returning oil from short circuiting to the oil outlet and its too long and is below the oil level.

[minetymenace]

You got your flow and return pipes the right way round?

[Blakey]

Pipes are crossed over. Inside pipe on the union to flow. Outside pipe with rockerbox feed return.

[Blakey]

Well it's stopped dripping!
The tank is empty.
Time to look at the oil pump methinks.

[Barry Creary]

On my B50 I had wet sumping about 100 mm over night and it was the oil pump shaft housing worn so I got it machined and bushed now I can leave it for months without having a sump full of oil

[kommando]

Your pump is leaking from the feedside to the scavenge side through the shafts and both non return valves are not working.

[Blakey]

Thanks chaps.
Soooooo.
Refurb existing one, find later cast iron one or sell a kidney and give the money to SRM?

Love those guys and they are in gods own country.

[kommando]

On Norton pumps the shaft leak is fixed by fitting O rings to the body where the shafts run. Should be easy enough to replicate on a Unit Single pump.

Here is a Norton one I did but substituted X rings.



You need a vertical mill to do it properly.

[Blakey]

Neat job but Ive not got a milling machine.
Mind you I have a birthday coming up!
What are your thoughts on the SRM pump?

[kommando]

Too much money compared to a refresh of a pump.

[Blakey]

Same thoughts.
Ive got a couple of good light engineering firms close by.
My local adult ed has a milling and turning course running soon. Maybe Ill enrol.

[Keefe]

Local college's running milling and turning courses seem to be very much a rarity nowadays. I just wish there was one near me.

I would definitely enroll on the course if it was me.

Good luck with it.

Keith

[Barry Creary]

I have a B50 iron pump that would need bushing but otherwise pumped oil good.

[Blakey]

Ill strip the pump when I get back off me hols, see whats going on.
Just got the top end back.
Rebored. +20
Head and barrel refaced.
Aquablasting brought everything up lovely.
Big thankyou to Hargreaves Engineering. Johnstown.