BSA B25 racing bike

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Re: BSA B25 racing bike

Post by madsundaysurvivor » Mon Aug 20, 2018 11:34 am

tonight I was trying more things.....
thank for your advices, I have reviewed them.
Yes, the cases aren't totally bolted, but they have 3 bolts and base cylinder nuts and I don't see gap.
the timing outter case is bolted and full seat (bearing with circlip).
I don't have in place chain sprocket and nut, because don't let me see the proximity between rear side outrigger plate and top gear pinion sleeve, but I'm sure that the pinion gear is totally seated in the bearing
The outrigger plate matches perfectly with the case and is well seated

I found one woodruff key (think that is from T110 o T120 of my used parts) fit good and I tried assembly the clutch hub, tigthing to 40 Nw/m

the Axial decenterig is 0,27mm, I fit the hub some times and the decentering is allways the same.
10.JPG
The vertical decentering is 0,45mm
11.JPG
All looks good, the gap to 40 Nw/m between outrigger plate and the clutch hub is 1,30mm, and It turns free.
12.JPG
The problem arrived when I tight to 70 Nw/m, then begins to touch, and to 80 Nw/m the hub was blocked against the plate
13.JPG
The mainshaft with the inner timming cover in place (totally seated) with the thrust and distance whaser fits, don't have any gap or slack (side to side). Should be some gap here?
14.JPG
I think that the mainshaft cone base is worn and the hub could be enter too much. I only need about 1 mm for don't touch de plate.

I have to put back the bearing (side transmisión) in place another time, to make sure but I think what I see that this is fit good.

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Re: BSA B25 racing bike

Post by minetymenace » Mon Aug 20, 2018 12:02 pm

Woodruff key: This should not make any difference, the drive is on the taper, not the key, I don't know why it is there unless it is just to aid assembly somehow. Leave it out during test assembly.

The taper shouldn't wear, try some blue on it and make sure you have a good interface.

There is no point measuring the run out on the part that the plates slide onto it is naturally a sloppy fit, measure the runout on the clutch hub itself.

I know you have said, but is it binding because:
a. The clutch hub is locking on the outer of the bearing in the bearing plate
b. The bearings are not in line, so when the shaft nut is tightened the bearings are binding?
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Thu Aug 23, 2018 3:56 pm

Yes, the hub touch aginst the outrigger plate
Following the Tom advices, crankcaes, plate and sprocket nut totally bolted, I have obtain 0,8mm.
Ccm britain tell me push the bearing until top gear pinion and regrind the outrigger plate. And I think laped rear clutch hub 0,5 mm, I can obtain 2mm more, this must be enough.
My cases are 1968, and I have read on internet that in the cases 1969 on, the distance between clutch cover plate and the gearbox bearing is less.
Is this true? perhaps this is my problem... <201

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Re: BSA B25 racing bike

Post by koncretekid » Fri Aug 24, 2018 2:30 am

I did not know that the earlier cases were different, so I can't advise you on that.

It would be helpful to try a different mainshaft, but I know they are probably scarce in your area. Even if you could borrow one just to make sure that yours has not been reground. You could try removing the the new cover plate and mounting the clutch complete with chainwheel as well as the motor sprocket to see if the sprockets line up. Normally, you need to shim the motor sprocket outward to get perfect alignment, but if the clutch hub seats too far onto the mainshaft (if the taper has been reground), the sprocket on the motor may not align with the chain wheel which would be a problem.

Otherwise, it looks like the PES plate may need some work to allow the bearing to seat further into it, and machining off some of the outer surface to clear the hub.

Tom

P.S. I finished rebuilding my TR25 motor and it lives again! I'll be heading to Colorado and on to Bonneville in 2 weeks.
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Fri Aug 24, 2018 8:26 pm

This is my main problem any test I have to do with another piece, I have to buy it outside of my country. My brother and I are the only ones who like the English bikes of the 50-60 in many kilometers around. Around here the classic bikes are Spanish, Italian, German or Japanese from the end of the 70-80. And the English there are very few and almost all pre-war or THUNDERBOLTS or BONNIES of the last years


I like your proposal. Tomorrow before regrind the cover plate, I'll put in place all clutch components (with the oem cover plate) and front engine sprocket and check this.

Another doubt is that I allways in my other bikes thight the gearbox sprocket nut, manually to the maximum that I can tighten. I have read in the manual that the tightening torque is 100 N·m, it seems too much for a nut so thin and not to damage it. How do you do it?

Good luck in Bonneville, you'll tell us ...

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Re: BSA B25 racing bike

Post by koncretekid » Sat Aug 25, 2018 12:16 am

I tighten that nut to 90 ft-lbs which should be 120 newton-meters using a suitable torque wrench and a 1-1/2" socket by wrapping a piece of chain around the sprocket and holding that with vise grips. I also have a 1-1/2" deep socket that I've cut and added a couple more inches to in order to change the nut even with the mainshaft installed which can be done by stopping the sprocket with a chunk of hard plastic, like a screwdriver handle or purpose made block.

You do not need to put any cover plate on, but it may show if you still have interference.
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Sat Aug 25, 2018 6:20 pm

Even if you could borrow one just to make sure that yours has not been reground. You could try removing the the new cover plate and mounting the clutch complete with chainwheel as well as the motor sprocket to see if the sprockets line up. Normally, you need to shim the motor sprocket outward to get perfect alignment, but if the clutch hub seats too far onto the mainshaft (if the taper has been reground), the sprocket on the motor may not align with the chain wheel which would be a problem.
Well, this morning I have done it..... and the result is a perfect aligment clutch and chainwhell (the chain well need a 0,2mm tightnees whaser).
IMG_20180825_132337.jpg
Then the problem is that the outrigger plate it's too wide for my mainshaft.

I have push the bearing 1'5mm until stop with the gearbox nut and grind the plate the same measure. everything seemed good....but no :(

only the thickness of bearing is too much.

And Now I have to options:

1º change de bearing 6005 C3 (12mm tickness) for 6905 C3 sealed (9mm tickness). but different outer diameter 47 VS 42 I'll have to made a spacer for fit in the outrigger plate

2º Can regrind the back side of gearbox sprocket 1mm and regrind and shorten the top gearbox thread 1 mm too ( I think that have enough space to the rear chain yet and for aligment).

<213 <213 <213 <213

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Re: BSA B25 racing bike

Post by beat » Sat Aug 25, 2018 7:14 pm

I vote for 1°
:ok

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Re: BSA B25 racing bike

Post by koncretekid » Sun Aug 26, 2018 11:50 am

"Well, this morning I have done it..... and the result is a perfect aligment clutch and chainwhell (the chain well need a 0,2mm tightnees whaser)."

Hopefully you meant that the engine sprocket will need the .2mm washer.

What is the total thickness of the outrigger bearing plate? Is the bearing recess bored completely thru? If not, can you make the bearing recess deeper by the required amount (1mm)? It needs very little thickness behind it, or none, because there is no thrust on the bearing. So you could bore the bearing plate completely thru and it should still work. If you do this, make sure you don't enlarge the O.D. on which the bearing seats, but it can be slightly larger beyond the original seat - -the bearing should still maintain its shrink fit on the remaining portion of the original O.D.

If the above won't work, your #1 sounds like the best. Maybe Mr. Cook already has another bearing plate made with the narrower bearing?

Tom
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Mon Aug 27, 2018 10:19 am

koncretekid wrote:Hopefully you meant that the engine sprocket will need the .2mm washer.
Yes.

The thickness of outrigger plate is about 12,3 mm, the bearing 12mm. the bearing can move foward and rear. I have push the bearing 1,5mm rear and regrind the front plate the same measure. Now the bearing is excels 1,2 mm on the rear side. Now no problem int the front, but the bearing touch before the top gear pinion and it doesn't tet seat the plate. Definitely 12mm bearing is too much for my engine.

I think too that the first option is best, a thin bearing with a Bush (1,5 Wall)

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Re: BSA B25 racing bike

Post by madsundaysurvivor » Sat Sep 01, 2018 11:22 am

Well the problem is solved, the solution was a thin bearing (16005 2rsr), it support less kg/ but I think will be enough.
Thank you all by your support.
Now my oil pump is dead. I have cleaned several times and plain the surfaces, but no turns freely.
I need buy one.
Wich is the best option?
-SRM pump (really is beter? Is much expensive)
-new oil pump three holes
-new oil pump two holes

Sorry for my lenguage, its very difficult for me... :oops:

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Re: BSA B25 racing bike

Post by koncretekid » Mon Sep 03, 2018 1:10 am

Excellent solution!

The 3 hole cast iron late model ('71-'72) oil pump is excellent, if you can find one. Make sure if you find one that it has an "S" stamped into the body which indicates B25. The B50 one has a "V" stamped on it and has narrower feed gears.

I have never tried an SRM so I can't comment on it.

Tom
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Mon Sep 03, 2018 8:53 am

then the best would be "cast iron three holes, S stamped"

There are some in internet that sell them as "new old stock".(some are LF Harris) I read in this forum some bad experiencies with old stock pumps, and about pumps that sell them like good condition and then don't work.

For this I had thougt in SRM pump, if my first purschase was a failure, with the second I would have already reached the Price of SRM

If I buy the three hole pump, I know that in my 68 case I have make a modificatión in the crankcase and in the timing inner cover.

But, Do you also make the third hole and put the stud? or Do you let them work with two studs?

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Re: BSA B25 racing bike

Post by Ian Hingley » Tue Sep 04, 2018 10:37 pm

I ran a 3-hole pump in a 2-stud Victor for many years. Just left the new top hole without a stud to engage with and used the existing 2 original studs.
No problem at all.
You have to take a file to the inner timing cover to make room the unused third boss, but I can't remember making any changes to the crankcase.

Good luck

Ian
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Thu Sep 13, 2018 11:26 am

Thank you ver y much. Already I have bought the NOS pump. I hope have good luck
The project goes ver y solwly. Now I am injuried and wait For my brother to help me

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Re: BSA B25 racing bike

Post by minetymenace » Thu Sep 13, 2018 3:26 pm

madsundaysurvivor wrote:Now I am injuried
OMG, what happened?
There is no evidence to support the notion that life is serious.
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Thu Sep 13, 2018 3:51 pm

My dear back, I'm already used to the afermath of an accident in a race years ago. Every few months my back has to remind me...

Thanks

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Re: BSA B25 racing bike

Post by madsundaysurvivor » Tue Sep 25, 2018 7:39 am

All ready I have the pump, complete clean and works nicely. I have been lucky.
IMG_20180921_104204.jpg
Now I am triying the Ed V shopevengineering oil conducts mods. But my English is very bad and don't understant completely

He says dril the oil port feed and the "A" hole to 0,1875"
And drill "C" , oil return port and sump conduct "G" to 0,220"
But what happen with "B", "D", "E" and "F"?

carter derecho bsa b25.JPG

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Re: BSA B25 racing bike

Post by madsundaysurvivor » Wed Nov 28, 2018 7:27 pm

Hello
I'm thinking about cranckcase breather for my B25 1968. I know that there is written a lot about this topic (I think I have read all and don't invent anything new)
I like the Stan Millard mod, using the primary chain cover like expansion chamber

But I can't make the tube weld for internal conexion. Then I've decided make an external conexion, with a 3/8 pipe from timing side to primary chain cover, and long oulet pipe of 1" from primary cover to the rear wheel. At the same time make three holes (1/8 bore) in the cranckcase primary side wall (same as in my T120s) just above the clutch oil level line, for return the oil possible excess in primary to the sump. I hope this will enough.
Think the B25 moves much less air volume that the B50.
In my racing bikes allways use free breather, I think that pcv valves will come into resonace and allways will be open. I don't have experience with reed valves.

What do you think about this? Please I accept any criticism.

Will I have a problem with the metal shaving of the chain and cluth returnig to crank?, I don't like remove the crank bearing seal.
Will I need another hole in the left crankcase wall?

Thank you for your attention.
tubo primaria.png
agujeros primaria.png

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Re: BSA B25 racing bike

Post by koncretekid » Thu Nov 29, 2018 11:43 pm

For sure, the B25 has only half as much "pumping effect" as the B50. I just added a breather attached to the tachometer port, as I am using a Scitsu tach. I didn't use a reed valve or any other one way valve. With the addition of the primary case to the crankcase volume as you are talking about, the change in pressure will be smaller than a similar arrangement for the B50, so is the one-way valve necessary? Following is a photo of my crankcase breather, fitting for low oil pressure light and for line up to the oil pressure gauge, and the A/F sensor in the exhaust pipe.
TR25 breather, etc..jpg
Breather and oil pressure fittings
Tom
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Re: BSA B25 racing bike

Post by minetymenace » Fri Nov 30, 2018 12:13 am

I was considering mounting a pressure gauge like that, if the instrument is on the yokes (triple Ts) have you got a flexible pipe round the steering head? Any breaks in that pipe will drop the big end oil pressure to somewhere around nasty.
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Re: BSA B25 racing bike

Post by koncretekid » Fri Nov 30, 2018 12:19 pm

minetymenace wrote:
Fri Nov 30, 2018 12:13 am
I was considering mounting a pressure gauge like that, if the instrument is on the yokes (triple Ts) have you got a flexible pipe round the steering head? Any breaks in that pipe will drop the big end oil pressure to somewhere around nasty.
The loop in the copper tube is what the old timers call a "service loop" thought to take the strain off the tube due to vibrations. I have a union in the line which connects to a nylon tube which continues up to the gauge on the yokes. However, so far, the gauge is the weak point, not that it developed a leak, but I have blown the needles off 3 of them. So I will look into using an electric sending unit at the front of the motor connected to an electric gauge on the yokes which should eliminate that possibility of a broken tube.

Tom
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Fri Nov 30, 2018 3:47 pm

Thanks for you answer.
Yes, it's my purpose. Do youh have any holes on the left crankcase to primary? And any to return the possible oil excess in primary chain?
About the gauge Prefer the threated fittings (hose rigid or flexible). The long and thin brained hoses with clamp to the gauge, by the use /vibrations can be lossen in the worst moment. Once in a triumph the pipe came out the gauge and I realized late when the rear wheel started to slide and my leg was an oil Bath.

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Re: BSA B25 racing bike

Post by koncretekid » Fri Nov 30, 2018 10:02 pm

madsundaysurvivor wrote:Thanks for you answer.
Yes, it's my purpose. Do youh have any holes on the left crankcase to primary? And any to return the possible oil excess in primary chain?
No, the primary cover is stock and I have not drilled the holes through to the crankcase. So oil is separate from the motor oil.

Tom

P.S. Has anyone tried an electric sending unit and gauge in place of the mechanical ones?
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Re: BSA B25 racing bike

Post by madsundaysurvivor » Tue Dec 04, 2018 1:22 pm

Hi
I haven't expirence with electronic presure gauges, but yes in electronic temp gauges, no problem,if you have a battery wiring they will work ok.
In europe a good trade for this instruments is "veglia" (for tachometer, temp, presure......) they are a good sensor. For motorcycles by the vibrations (no necessary for cars) a ¿gliceline? Instruments .
Regards
Ram'on

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