In search of reliable B25 oil pressure.

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In search of reliable B25 oil pressure.

Post by lathejack » Sat Nov 07, 2015 9:02 pm

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Soon after recently buying my 1969 B25 Starfire I plumbed in a pressure gauge. With fresh 20/50 oil and a cold engine it produced 20 PSI at a slow idle, 40 PSI at fast idle and 70 PSI while reving away. In comparison the OIF Fleetstar I checked produced 70 PSI at a very slow idle.

Two weeks later the kickstart return spring broke, so i took the opportunity to also remove the inner cover to check the pump, crank end quill and the seal. Slight mushrooming of the crank end was carefully cleaned up and the quill polished, and the tired and slightly damaged end feed seal was replaced.

I noticed the pump spindle seemed tight, when I removed the pump I found the spindle could only just be rotated with considerable effort. The pump top cover bore was found to be half a thou smaller than the spindle shaft in places. So I clamped it to the mill table and reamed the bore to the correct size, this set up ensured the bore remained square to the flat mating face.
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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sat Nov 07, 2015 9:39 pm

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Despite the zinc alloy bodied pumps having a poor reputation, this pump was still in excellent internal condition. There was no detectable wear and still with minimal clearance around the circumference and the side faces of the internal gears.

Bench testing showed not only a good flow of oil but also plenty of resistance when the ports were blocked off. Using a high pressure oil can to pump oil into the feed and scavenge inlet ports failed to force oil past the stationary internal gears and out the other side of the oil pump, a very good sign that all is well.

All these tests are something that a recently purchased ghastly new LF Harris 3 stud cast iron pump failed spectacularly at, what a truly hideous and useless product that proved to be, and was instantly returned to the dealer for a refund.
Last edited by lathejack on Wed Nov 11, 2015 2:58 am, edited 1 time in total.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Sat Nov 07, 2015 9:45 pm

You will be well served by a standard 1971 B25 pump imo. <1011 .. If a '67-'68 case is used a slight relief in the crankcase by the 3ed mounting surface will be needed. It seems that '69 and newer cases do not require that. Were your oil pressure readings with the stock pop off valve in place? When I 1st tried using an oil pressure gauge on the "$75 BSA" I used the port the ball check valve should have been in. To my surprise, whilst it showed 40 lbs @ idle and 70 riding down the road, reving it brought over 100 lbs and I went to a later transmission side cover with a separate port for the pressure gauge and then it popped off and a bit over 50 lbs at high rpm.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sat Nov 07, 2015 10:40 pm

Hi HPbyStan.

Yes I agree, but the problem seems to be getting a good genuine 3 stud iron pump, most descriptions of used pumps for sale simply say they "spin free" which proves nothing of how well they really work. I have three iron pumps and not one of them is as good as any of the three zinc pumps I also have. The original zinc pump from the bike performs faultlessly and produces much more pressure than is required, but apart from the common binding problem, it did have a manufacturing fault which I will show later. But as you suggest, an iron pump is preferable.

New pattern pumps like the LF Harris iron pump I bought can be horrifically badly made. The Harris pump I was sent had a spindle that had been entirely ground and filed by hand where the external gear fits. The third mounting lug was not flush with the pump bodies mating gasket face, but instead was a few millimetres back with its mating face roughly filed by hand, plus the bottom cover edge had been ground flush to the body mating gasket face by hand while in situ, damaging the gasket face. Also, just like the new LF Harris Triumph Trident pump I bought 25 years ago, it's internal clearances around all sides of the pump gears and circumference were enormous, so bad that the gears and both shafts slopped around inside so generating any pressure was impossible. Good job I bench tested them first.

A local dealer has a very large stock of pump parts, a tonne in weight he told me. But of the two quite expensive and supposedly new genuine iron pumps he showed me, one was just another Harris pattern pump with signs of being previously used, and the other had a very large amount of play between the spindle and the bore in the top cover. So ordering one of these "new genuine" pumps may still not get you something that is any good.

It's a tricky hobby, this Unit Single lark!
Last edited by lathejack on Sun Nov 08, 2015 1:26 pm, edited 2 times in total.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sat Nov 07, 2015 11:04 pm

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I hope these pics are clear enough. They show the two scavenge gears that were inside the original pump from my B25. The reworked pump was thoroughly cleaned and rinsed, but when assembled it now turned freely apart from a tight spot, once every revolution.

Watching the two scavenge gears rotate showed that the tiny amount of backlash between them disapeared at the point of the tight spot. Measuring the gears confirmed that their bores were concentric to their circumference.

The fault and cause of the tight spot was then traced to just one of the scavenge gears. It was found that, although the circumference of this gear was concentric to its bore, the gear teeth had not been machined and ground concentric to its bore. The faulty gear on its edge in one of the pictures has been turned round in the other picture. The difference in the thickness at the tip of that gears teeth can just be seen when one side of the gear is compared to its opposite side, showing how much off centre the teeth have been formed. They were replaced with another pair.

Despite their reputation, these genuine BSA oil pumps are usually very well made. With quality of machining and essential very small internal clearances and very fine tolerances that most pattern part manufacturers make absolutely no attempt to replicate, but a faulty genuine part does pop up now and then.
Last edited by lathejack on Sun Jul 10, 2016 11:21 pm, edited 5 times in total.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sun Nov 08, 2015 12:22 am

HPbyStan, I have just read your reply again. To get realistic results, my pressure readings were with the standard ball and spring type relief valve in place, more about that little horror to follow. My 1969 inner timing cover has the little oil port blanking plug underneath, so I machined up some fittings on the lathe and the gauge is plugged in there.

I was very surprised to find out that earlier engines do not have this oil port, or anywhere else to check oil pressure. So if a pressure gauge is connected in place of the relief valve, very high pressure can be produced without the valve in place to limit it. But with the relief valve in place the pressure is very different, as you found out. I would not have had the courage to run the engine with a gauge in place of the relief valve.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sun Nov 08, 2015 1:32 am

So, oil pump problems corrected, crank end repaired plus a new seal and O ring . The spring loaded ball bearing type relief valve was reseated with a new ball. All systems go! Well, almost.

The oil pressure readings had doubled from those I mentioned at the beginning, with a maximum of 80 PSI when the relief valve kicked in. So with my new crash helmet, MOT and insurance I hit the road on a motorcycle for the first time in 23 years, and the first time ever on a BSA.

But during three consecutive rides out on different days the oil pressure would take a very sudden drop from a hot 55-60 PSI at medium revs, down to 20 PSI.

The problem was traced to the ball type relief valve. No amount of fiddling, reseating or new balls and springs would keep it working for more than 8-10 miles. The oil was new, with a filter fitted and no contamination was flowing to the pump and relief valve.

So I gave up with it. From 1970 the crankcases are machined to accept the spring loaded piston type relief valves with a 7/8 thread. Cases up to 1969 have a 5/8 thread which is also machined at a different angle to later types which also results in the two oil ways being in different positions than those in later cases. So you can't simply fit a later type valve.

So I designed and machined up my own piston type relief valve to replace the ball type, and fit straight into the earlier crankcase without requiring any modifications to the case. The main body is bronze with a hardened precision ground steel piston.

Excess oil that is exhausted out the valve escapes down the original oil way in the case. The metal to metal seal between the tip of the valve body and the original ball valve seating in the crankcase works perfectly well, it contacts just about where the original ball valve did.

Although it's a bit of a prototype with refinements planned to a small batch of future examples, it works without trouble, maintaining constant pressure of 50-65 PSI when hot. The valve is set to operate at around 80 PSI, on a cold start up the pressure instantly goes slightly beyond that.
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Last edited by lathejack on Sun Jun 12, 2016 8:59 pm, edited 8 times in total.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Sun Nov 08, 2015 1:46 am

Looks good !!!

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sun Nov 08, 2015 1:53 am

This shows the new relief valve body and spring in place, then with the bronze domed nut I made fitted, also the pressure gauge connection to the left. Without the gauge fitted right from the start to tell me what was going on, who knows what catastrophie could have ensued.

Do those ball type relief valves have a habit of playing up? If so, no wonder the earlier B25 engines gained a reputation for big end and rod failure with a combination of that ball valve and no way of knowing what the oil pressure was doing while riding, plus youthful thrashing and neglect.

The ball type valve is very vulnerable to being held open by any particles in the oil, but it seems to have a mind of its own anyway, even with uncontaminated clean oil. The piston type valve does not have this problem, as the seal is formed by the close fit of the piston in the bore, not a seat.
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Last edited by lathejack on Sun Nov 08, 2015 10:55 am, edited 1 time in total.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sun Nov 08, 2015 2:04 am

Thanks HPbyStan, the design and production of the valve was a rush job done overnight and into the morning, ready for a ride to the local small vintage show the same day as soon as it was finished.

There was no time for a thorough test, just a bench test and adjustments in the workshop after fitting to the engine. Thankfully I found a pack of suitable springs in my stock, and fibre sealing washers to make fine adjustments.

It is interesting what you can achieve when under pressure, or should that be low pressure? Well, you know what I mean.
Last edited by lathejack on Mon Nov 09, 2015 3:02 pm, edited 2 times in total.

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Re: In search of reliable B25 oil pressure.

Post by midgie » Sun Nov 08, 2015 10:13 am

lathejack wrote:This shows the new relief valve body and spring in place, then with the bronze domed nut I made fitted, also the pressure gauge connection to the left. Without the gauge fitted right from the start to tell me what was going on, who knows what catastrophie could have ensued.

Do those ball type relief valves have a habit of playing up? If so, no wonder the earlier B25 engines gained a reputation for big end and rod failure with a combination of that ball valve and no way of knowing what the oil pressure was doing while riding, plus youthful thrashing and neglect.
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you are spot on there, with 'the youthful thrashing' I would like a £ for every b25 that 'burst' under the over enthusiastic young jockey trying to keep up with the Japanese machines. great job on the pressure release valve looks fantastic :thumb

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Re: In search of reliable B25 oil pressure.

Post by Mr Mike » Sun Nov 08, 2015 4:40 pm

lathejack,
I had the problems you describe on my A65 twin. I made my own oil pressure relief system that relieves directly to the tank and I also installed a gauge. The result was 50-55 psi going down the road hot and 20-25psi at idle. That's what you need on a plain bearing motor. If you are interested I can send you a writeup. It is quite simple and there are no permanent modifications to the engine.
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Re: In search of reliable B25 oil pressure.

Post by lathejack » Mon Nov 09, 2015 2:50 pm

Midgie.
I was hoping that the B25's reputation was undeserved, but from what you say, I see maybe it really isn't.
If all the broken B25 rods were laid end to end, I wonder how far they would stretch. By the sound of it, probably further than the distance a Barracuda could travel while doing 80 MPH.

Mr Mike.
Your modification sounds interesting, and your offer of a write up would be welcome. Do some of the A65 engines also have a ball type relief valve?
Your bike seems to have healthy oil pressure now, so does your engine still retain the plain bush timing side crank bearing?
Last edited by lathejack on Wed Feb 10, 2016 9:35 pm, edited 1 time in total.

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Re: In search of reliable B25 oil pressure.

Post by kommando » Mon Nov 09, 2015 3:58 pm

The A65 follows similar development pattern to the Unit singles except the timing side was always a bush, why they retained the bush on the largest bike they did until the Rocket 3 is odd but no doubt typical BSA. As was the odd decision to use whitemetal on the big ends of the B25 and A65, both highly stressed engines when Norton and Triumph were using Tri metal Copper/lead which is a stronger bearing by a huge amount.

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Re: In search of reliable B25 oil pressure.

Post by Jeff K » Mon Nov 09, 2015 4:13 pm

kommando wrote:The A65 follows similar development pattern to the Unit singles except the timing side was always a bush, why they retained the bush on the largest bike they did until the Rocket 3 is odd but no doubt typical BSA. As was the odd decision to use whitemetal on the big ends of the B25 and A65, both highly stressed engines when Norton and Triumph were using Tri metal Copper/lead which is a stronger bearing by a huge amount.
Interesting that they used different materials. I always would order and use the T100 rod bearings for the B25/TR25. Not because I knew better, but only because for a couple of dollars more I would get two sets. :ok Dumb luck, I was doing the right thing and not knowing it. :thumb
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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Mon Nov 09, 2015 4:52 pm

lathejack wrote:
Although it's a bit of a prototype with refinements planned to a small batch of future examples, it works without trouble, maintaining constant pressure of 50-65 PSI when hot. The valve is set to operate at around 80 PSI, on a cold start up the pressure instantly goes slightly beyond that
I'm interested when you get ready to sell them... Stan

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Tue Nov 10, 2015 12:16 am

Hi Stan.

Gosh! I hadn't given any serious thought to selling any. So I better get a move on and make a small batch with any refinements and improvements nessesary, and give them a thorough testing to prove the design.

Me, a manufacturer and international exporter of BSA motorcycle components! To think that just four months ago bikes were just a faint memory rattling around in my distant, youthful past. I blame my return on that Rupert Ratio book I bought at the beginning of the year.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Tue Nov 10, 2015 1:50 am

Yeah, that dude is a bad influence on all of us... <1011

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Re: In search of reliable B25 oil pressure.

Post by Mr Mike » Tue Nov 10, 2015 7:19 am

Lathejack,
A65's first used a ball spring relief and later a piston/spring relief. The design of the A65 pressure relief cavity is highly suspect. I plugged the return port in the relief cavity and made an adapter bushing for the cavity. Into the bushing I threaded a tee with one side going to my gauge and the other side to a very small spring/ball relief which in turn tees into the return to the tank. I will be honest the small relief valve could not handle the flow on cold startups using 20w50 oil. It pegged my new oil filled gage at 120 psi. The small relief just was too small to relieve cold oil but it worked fine once up to temp. So I switched to 10w30 and it relieved just fine. About 75 psi at cold idle and even revving it doesn't get much higher. 20-25 psi at hot idle and 50-55psi at speed. There is some hysteresis but it is small. I suspect that the pressure relief on the A65 has several problems: (1) Leak by in the cavity, (2) Vibration may cause chatter of ball on the seat, (3) hysteresis. My system cures all three: (1) the leaking cavity return is sealed, (2) no vibration, the relieve valve is isolated by rubber hose, (3) Valve is low hysteresis.
I go to the britbike site and I made a set of parts of one guy that does high mileage on A65's. He wants me to send him two more kits for his other A65's. But other than that I have had little interest but they are always complaining about low oil pressure on a65/50's and B25's. Hell, BSA knew that too. The changed the relief valve, upgraded their pumps and even changed their ignition as they thought that was causing bottom end failures. IMO it was always poor oil pressure. Also a lot of rebuilders did not (and still don't) align bore their bush on rebuild. Even misalignment of .001" will wear out a bush in a few thousand miles and the oil pressure fall off and then kerboom.

I'll find you my writeup tomorrow on the mod and maybe a pic.

Mr Mike

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Re: In search of reliable B25 oil pressure.

Post by minetymenace » Tue Nov 10, 2015 8:36 am

Mr Mike wrote:bore their bush
Are you talking about the timing side main here? Us single riders have to make do with polishing our quills.
There is no evidence to support the notion that life is serious.
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Re: In search of reliable B25 oil pressure.

Post by Mr Mike » Wed Nov 11, 2015 1:05 am

MM,
For sure. A common problem with A65's. I never had to redo my bottom end on my B25. It was quite reliable for a daily rider for two years. I sold the B25 and got a B44 which could do everything a B25 did with a whole lot less effort. Never looked back but I can't knock the b25. It served me well.
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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Mon Dec 14, 2015 2:30 am

lathejack wrote:Hi Stan.

Gosh! I hadn't given any serious thought to selling any. So I better get a move on and make a small batch with any refinements and improvements nessesary, and give them a thorough testing to prove the design.

Me, a manufacturer and international exporter of BSA motorcycle components! To think that just four months ago bikes were just a faint memory rattling around in my distant, youthful past. I blame my return on that Rupert Ratio book I bought at the beginning of the year.
Any update on your world wide marketing of this needed valve?

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Tue Dec 15, 2015 8:12 pm

Hello Stan.

I have made a few small alterations to the design of the valve body, and made a small start on machining one up. Spare time to spend tinkering in the workshop can be a bit limited.

I will try and get a bit of a move on. If I get the modified valve finished soon, then after some testing on and off the bike I may have some ready early in the new year.

I have been running the bike with the first valve I made since September. Although I haven't done a high milage with it, it has been totally reliable so far. Which is something that could not be said of the ball type valve on my bike.

I cruised the Starfire along at 70 MPH for a few miles the othe day. Ok, not exactly mega speed, but it is revving fairly high for an old Brit bike at that speed, and it did stay in one piece and actually smoothed out at around 60 MPH after a slight rough patch at 50.

I will keep you posted on progress.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Wed Jan 20, 2016 7:55 am

Time for my monthly question. When will mine be arriving at 1401 Barham Av. ?

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Re: In search of reliable B25 oil pressure.

Post by Jeff K » Wed Jan 20, 2016 5:45 pm

I also would be interest in one. Sounds like the start of a pattern part production run? :mrgreen:
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Re: In search of reliable B25 oil pressure.

Post by David S » Fri Jan 22, 2016 1:31 am

Count me in too! I need one for my 71 Triumph T25SS.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Fri Jan 22, 2016 4:49 am

David, your '71 should already have the upgraded design with a piston instead of a ball and spring flopping around in there.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Sat Jan 23, 2016 3:42 pm

I will be trying to get on with these valves during this week and next, other commitments permitting.

As Stan says, a 71 bike already uses a piston type relief valve, so does not require the valve that I am producing. If you need a new relief valve for one of these engines, then simply replace it with a new original type which are readily available. As long as the bike has the correct type cases.

My valves are only designed for pre 1970 cases that are originally fitted with the ball type relief valves, and they won't fit or work in later cases anyway.

The later standard fitment piston type relief valves usualy work perfectly well in my experience. The only trouble I have ever had with one was a new pattern item that looked like it was made from extruded steel tubing. It's bore had been formed with a die, with a very shallow and badly formed relief groove that leads from the back of the piston to one of the oil exhaust ports.
The result on cold start up when fitted to my T140 was oil pressure rocketing up to 150 PSI and beyond at idle, before I managed to kill the engine. Refitting the old original valve restored correct operation with 80 - 85 PSI.

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Re: In search of reliable B25 oil pressure.

Post by TR250 » Sat Jan 23, 2016 7:38 pm

HPbyStan wrote:David, your '71 should already have the upgraded design with a piston instead of a ball and spring flopping around in there.
Hello,
very good job, but it raises a question, do I need it on my '69 Triumph TR 25? It has the stock pump and relief valve. I will never know until something goes wrong :shock:

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Re: In search of reliable B25 oil pressure.

Post by kommando » Sat Jan 23, 2016 7:43 pm

Its needed for 66 to 70 Starfires and rebadges TR25W's.

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Re: In search of reliable B25 oil pressure.

Post by hwan » Thu Jan 28, 2016 12:43 pm

interesting stuff from HPstan - better check what cam cover i am about to fit - i presumed it was a later type as it has a pressure switch.

Heads up on CI oil pumps is that the B50 pump is different from the B25 pump - the gear teeth are visably different and i think the widths are different giving a different suction/feed ratio.

I had three CI punps - two of which were the B25 type, one of which was supposed to come out of a B44 ?

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Thu Feb 11, 2016 1:09 am

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Well I have finaly been making a bit more progress with a small batch of my pre 1970 B25 pressure relief valves. I have been working on the valve bodies at the moment, but ran out of material at this point, but still enough for eight valves.

I visited the Newark Classic Bike Show in December, and there was a trader there selling a range of metal stock. He had some bronze and brass bar I needed, but I noticed him being slow to respond and rather unfriendly to a visitor who was asking for his web address and contact details. So I thought he can get stuffed, I won't buy from unpleasant twats like him.


Anyway, must keep at it and get these completed soon.

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Re: In search of reliable B25 oil pressure.

Post by David S » Thu Feb 11, 2016 1:35 am

Thanks for letting me know about the 71 T25/B25 having the piston style relief valve.I will check to see that it is correct.

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Re: In search of reliable B25 oil pressure.

Post by WeirdTim » Thu Feb 25, 2016 2:57 am

Been really educational reading this thread. Like a few, I may be interested in one or two of your valves if they are within my play budget!!

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Thu Feb 25, 2016 9:38 pm

Well I am making progress slowly, I have the valve bodies finished and need to make a start on the pistons and domed nuts.

I don't have CNC machines, they are produced on good old fashion manual machine tools, so each one takes quite a bit of time to make.

I did not originally intended to sell any, but whenever I make something I usually make several. But a few people seem interested and the valve does seem to work fine. As for price, well I thought a similar figure to the cost of a good quality later piston type relief valve that is used on the engines from 1970 onward.

Maybe I ought to see if I can patent the design, it could just end up being copied and then Ebay might be swamped with them.

Now, where did I put that fag packet with the drawing on it?
Last edited by lathejack on Thu Feb 25, 2016 10:20 pm, edited 1 time in total.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Thu Feb 25, 2016 10:02 pm

Mr Mike.

I have just been re reading your interesting post regarding your relief valve for BSA twins. It never occurred to me that vibration could be one of the causes of problems with the original ball type valve.

I am surprised you have not had much interest in your new relief valve. Anything that makes an important improvement such as this is worth having, especially as it is relatively inexpensive.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Fri Feb 26, 2016 12:18 am

well, I need one for the '68 B25 I'm working on and would like two of them.

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Fri Feb 26, 2016 1:42 am

Ok, I did start out with eight valve bodies, but made an irreversible error on one of them, so a swift and very heavy hammer blow eliminated that one.

I am off to the Newark Autojumble on Sunday, so may pick up some more material to make several more. I am taking the van, and hope to fill it with a B50, a B44 and a mass of associated parts, you just never know what's going to turn up there.

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Re: In search of reliable B25 oil pressure.

Post by HPbyStan » Tue Mar 29, 2016 3:00 am

As this saga started in early November I didn't look for a plan B. It's spring now and time to be testing. Are you my guy or do I need to rebuild the engine with newer cases?... Stan

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Re: In search of reliable B25 oil pressure.

Post by lathejack » Wed Mar 30, 2016 8:59 am

I'm sorry I have failed miserably on the time scale, they are finished and packed. I am off work on Friday so will be heading into town to the post office.

I am hoping that posting them to the U.S. is more straightforward than I have imagined.

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