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Cam profiles BSA unit singles #226
01/10/05 7:52 pm
01/10/05 7:52 pm
Joined: Nov 2001
Posts: 98
Netherlands
J
Jacco van D. Offline OP
BritBike Forum member
Jacco van D.  Offline OP
BritBike Forum member
J
Joined: Nov 2001
Posts: 98
Netherlands
I recently bought an incomplete and dismantled 1971 B25SS engine. In the box with spares, I found 8 camshafts. I measured them and found roughly 3 different profiles. Who can help to identify the correct camshaft for the B25SS engine.

Regards, Jacco


Triumph T100T 1969
Triumph TR6R 1972
Triumph T25T 1971
BSA B25 Fleetstar 1968
Laverda 750SF 1971
TWN Boss 1954
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Re: Cam profiles BSA unit singles #227
01/10/05 11:56 pm
01/10/05 11:56 pm
Joined: Aug 2001
Posts: 1,839
British Columbia
hh Offline
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hh  Offline
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Joined: Aug 2001
Posts: 1,839
British Columbia
They are possibly a C15/B40, SS80/90, a B25/B44/B50, and a B44GP/B50MX cam. If you throw up a picture end on of the cam, I'll compare them to a known TR25W/B25 cam that I have handy. The MX is pretty obvious next to the B25 since it has much rounder lobes. The B25 looks quite pointy. If you're going to get into the singles at all, you should get the book: The Rupert Ratio. It has actual size cam profiles in it.


"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
Re: Cam profiles BSA unit singles #228
01/11/05 8:13 pm
01/11/05 8:13 pm
Joined: Nov 2001
Posts: 98
Netherlands
J
Jacco van D. Offline OP
BritBike Forum member
Jacco van D.  Offline OP
BritBike Forum member
J
Joined: Nov 2001
Posts: 98
Netherlands
Sorry, no photo's yet, but I have measured the profiles .
1. Total height of lobe 29,8 and 29,8. Base circle 22,25. No marks on cam.
2. Total height of lobe 28,1 en 28,1. Base circle 20,6. Mark S on cam.
3. Total height of lobe 28,0 en 28,35. Base circle 19,9. Mark 40-478 on cam.
4. Total height of lobe 27,7 en 27,7. Base circle 20,0. No marks on cam.
5. As 4
6. Total height of lobe 28,1 en 28,4. Base circle 19,9. Mark Y on cam.
7. Total height of lobe 26,7 en 26,7. Base circle 20,0. No marks on cam.
8. Total height of lobe 25,75 en 25,75. Base circle 18,35. Mark 7 on cam.

Cams 4, 5, 7, 8 have a slim profile.
Cams 2, 3, 6 have a fat profile.
Cam 1 has a very fat profile.


Triumph T100T 1969
Triumph TR6R 1972
Triumph T25T 1971
BSA B25 Fleetstar 1968
Laverda 750SF 1971
TWN Boss 1954
Re: Cam profiles BSA unit singles #229
01/12/05 1:08 pm
01/12/05 1:08 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

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Joined: Sep 2002
Posts: 7,813
Seattle
Jacco,

As hh said, the Rupert Ratio book has a pretty good description of these cams. The 20 mm base circle should be for the distributor engines (C-15 and B-40) and should only be used with the curved type cam followers. These come in two varieties, standard (4, 5, 7) and SS80/90(2, 3, 6). The larger base circles are for the B25, B44, and B50. There are also two varieties of these as well, a standard one and a sports cam for the B44 GP and the B50 MX (1). These should only be used with flat cam followers. The other difference between the early and late cams is that the bearing ourboard of the gear is, I believe, smaller on the early cams. Your cam no. 8 looks like it's an early one that's had the bejeezys ground out of it and no. 7 has either been worn like nobody's business, is an oddball, a custom grind, or maybe a tiger cub cam, since the lift is way off. Incidentally, according to all the info I've been able to scrape up, all of the cams made by BSA should have the same lift: 8.76 mm (.345").

Remember, the advice is free - weigh it accordingly.

-alex


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: Cam profiles BSA unit singles #230
01/14/05 7:00 pm
01/14/05 7:00 pm
Joined: Nov 2001
Posts: 98
Netherlands
J
Jacco van D. Offline OP
BritBike Forum member
Jacco van D.  Offline OP
BritBike Forum member
J
Joined: Nov 2001
Posts: 98
Netherlands
Thanks for the info.

I noticed that none of the cams have a taper for an advance-unit. So they all are for a pre 65 bike (C15/SS80/B40?SS90).

Regards, Jacco


Triumph T100T 1969
Triumph TR6R 1972
Triumph T25T 1971
BSA B25 Fleetstar 1968
Laverda 750SF 1971
TWN Boss 1954
Re: Cam profiles BSA unit singles #231
01/17/05 4:29 pm
01/17/05 4:29 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

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Alex  Offline

BritBike Forum member
Joined: Sep 2002
Posts: 7,813
Seattle
Unit singles do not use a taper to mount the advance unit. It sounds like all but one is for the early models. The other way to tell the difference is that the outboard bearing journal is smaller for the early models and the gear is dished as opposed to solid.

Cheers


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.
Re: Cam profiles BSA unit singles #232
01/17/05 6:16 pm
01/17/05 6:16 pm
Joined: Aug 2001
Posts: 1,839
British Columbia
hh Offline
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hh  Offline
BritBike Forum member
Joined: Aug 2001
Posts: 1,839
British Columbia
Alex, all the unit singles I have have a taper to mount the advance unit, and I have a Boyer specifically designed for the unit single that has the same tapered rotor as the unit for the twins. They don't have a location pin like Triumphs though.


"Beer is proof that God loves us and wants us to be happy" - Benjamin Franklin
Re: Cam profiles BSA unit singles #233
01/18/05 3:15 pm
01/18/05 3:15 pm
Joined: Sep 2002
Posts: 7,813
Seattle
Alex Offline

BritBike Forum member
Alex  Offline

BritBike Forum member
Joined: Sep 2002
Posts: 7,813
Seattle
hh, after you mentioned this, I went back and looked at all the stuff I had. I had mistakenly looked at what appears to be some oddball cam, maybe an F-engine or something, that appears to be a later one with no taper. I went and looked at the WD (sidepoints) engine that I have and it DOES have a taper on it. So, it appears that I jumped the gun, here. It does look like the sidepoints cams have a taper in them. Funny, there is no reference to tapers in the Haynes manuals or the Rupert Ratio book. So, the upshot appears to be:

-distributor engine cams: no taper
-sidepoints engine cams: taper

Thanks for keeping me honest, hh.


A smattering:
'53 Gold Flash
'67 Royal Star
'71 Rickman Metisse
'40 Silver Star
'37 Rudge Special
sixtyseventy Lightboltrocket road racer...and many more.

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