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#704356 - 08/08/17 8:30 pm B50 chain length?  
Joined: Sep 2014
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Tigernuts Online content
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Tigernuts  Online Content
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Naarfuk, UK
I'm at the stage with my B50 rebuild where I;m almost ready to put a rear chain on. The one it came with is far too knackered to re-use. It is also long enough to go around the massive 70T rear sprocket the bike came with!

Doe anyone know how many links needed for 17T gearbox and 52T rear sprockets? I've asked this on the B50.org forum but people on there seem to find it an odd question, as if there is no right answer! There obviously is a right answer though, and if anyone on here can let me know what it is, I'd much appreciate it.


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#704376 - 08/09/17 12:11 am Re: B50 chain length? [Re: Tigernuts]  
Joined: Aug 2001
Posts: 6,604
Jon W. Whitley Online content
Jon W. Whitley  Online Content



Joined: Aug 2001
Posts: 6,604
Vermont
17 T front and 52 T rear would require a 106 link chain.


Jon W.


1957 6T Thunderbird 650
1971 TR6R Tiger 650
1955 Tiger 100 - Project
1970 BSA A65F 650 - Project

#704408 - 08/09/17 10:19 am Re: B50 chain length? [Re: Jon W. Whitley]  
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Tigernuts Online content
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Tigernuts  Online Content
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Naarfuk, UK
That's good of you Jon, thanks. I knew there must be an answer!


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#704428 - 08/09/17 2:26 pm Re: B50 chain length? [Re: Tigernuts]  
Joined: Jun 2002
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Peter Quick Online content
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New Hampshire
A likely reason that folks on B50.org didn't have an easy answer for you is that any chain you buy you need to shorten. In the 520 size 120 link chains are the norm as far as what is for sale. One just pulls the chain onto the assembled wheel and motor (wheel in forward position) and mark the chain where to cut. Pull it off cut it and re-assemble. That way no mistakes are made in the length/link calculation. In the time it would take me, or have others, research what length chain I would need based on my sprocket combination I'd have already done the above and already had a mounted chain.

Peter


check out: www.bsaunitsingles.com
2500 BSA part numbers with inventory in stock just for the unit singles!
#704432 - 08/09/17 3:06 pm Re: B50 chain length? [Re: Tigernuts]  
Joined: Aug 2001
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Jon W. Whitley Online content
Jon W. Whitley  Online Content



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Originally Posted by Tigernuts
That's good of you Jon, thanks. I knew there must be an answer!



You are welcome.


Jon W.


1957 6T Thunderbird 650
1971 TR6R Tiger 650
1955 Tiger 100 - Project
1970 BSA A65F 650 - Project

#704446 - 08/09/17 5:39 pm Re: B50 chain length? [Re: Tigernuts]  
Joined: Dec 2004
Posts: 8,825
kommando Online content
kommando  Online Content


Joined: Dec 2004
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Scotland
And the comments at B50.org on the adjuster are valid too.

#704461 - 08/09/17 8:26 pm Re: B50 chain length? [Re: kommando]  
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Tigernuts Online content
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Tigernuts  Online Content
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Naarfuk, UK
I think my comments on there about Triumph chain lengths being much more precise are also valid. I loved my B50 that I had in my youth. Now that I've been rebuilding another one, having done several unit 750 Triumphs, I have to say that I find the engineering almost embarrassingly crude, in comparison. So many vague areas, design problems looking for home made solutions or at least, improvements. They make T140s seem very advanced, and that isn;t something I thought I;d find myself saying!


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#704465 - 08/09/17 8:49 pm Re: B50 chain length? [Re: Tigernuts]  
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Andy Higham Online content
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Andy Higham  Online Content
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Bolton Lancs UK
Originally Posted by Tigernuts
I think my comments on there about Triumph chain lengths being much more precise are also valid. I loved my B50 that I had in my youth. Now that I've been rebuilding another one, having done several unit 750 Triumphs, I have to say that I find the engineering almost embarrassingly crude, in comparison. So many vague areas, design problems looking for home made solutions or at least, improvements. They make T140s seem very advanced, and that isn;t something I thought I;d find myself saying!


B50s are in reality an over bored beefed up tiger cub engine. Mr Turner took the easy way when designing replacements for the C12, B31, B33 etc. In most respects the earlier engines were far superior


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"
#704507 - 08/10/17 10:53 am Re: B50 chain length? [Re: Andy Higham]  
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Tigernuts Online content
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Tigernuts  Online Content
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Joined: Sep 2014
Posts: 408
Naarfuk, UK
Very true. Its amazing that B50s work as well as they do (and when they're good,they really are very good). The T140 is basically a 1937 design so even older in it origins than the BSA unit singles, and they work far better than they should too. I think the reason why the 750 triples are so much faster and more reliable (as racers) is that they were actually designed from scratch in the modern age (1967?). Stretching engines designed to produce a handful of horsepower ever further, until just below the very limits of their capabilities, was something BSA, Triumph and Norton specialised in, with surprising success.


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#704514 - 08/10/17 12:17 pm Re: B50 chain length? [Re: Tigernuts]  
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Andy Higham Online content
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Andy Higham  Online Content
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Bolton Lancs UK
Triples were not designed from scratch. The engine is essentially one and a half daytona T100 engines with a T120 gearbox behind and an Austin mini clutch


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"
#704567 - 08/10/17 10:00 pm Re: B50 chain length? [Re: Andy Higham]  
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Tigernuts Online content
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Tigernuts  Online Content
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Naarfuk, UK
Have you ever owned one and rebuilt one from scratch? I can assure you there is a lot more to a BSA/Triumph triple engine than that! But I'm not here to argue, so I'll say no more on the subject unless there's some point.

Last edited by Tigernuts; 08/10/17 10:00 pm.

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#704606 - 08/11/17 10:22 am Re: B50 chain length? [Re: Tigernuts]  
Joined: May 2004
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BSA_WM20 Online content
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BSA_WM20  Online Content
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Sydney Australia
Well according to the bigraphies of the designers of the time Andy is correct.
In fact they claim the prototypes were actually made by cutting up engines & joining them together .
The diagrams in the parts books were definately cut & paste Triumph parts books and if you need proof, have a very close look a the cam shaft or where the oil pump sits.
And yes production models had to be re-engineered a bit in order to make them almost reliable and to facility manufacture.
Without checking & I am sure those who love the 2 redundant cylinders will correct me if I am wrong, but Triumph was ready to put it ito production back in 63 but the board would not have a bar of it till Turner did his tour of Japan and realized the H4 was going to kill the USA big bike market.
HE may have been a garbage engineer but he was a good stylist and highly in tune with motorcycling trends.

In the days of desk top dynos we easily forget just how difficult it iwas to design an engine back in the slide rule days
If you look at the bore & stroke ratios you can see that BSA lucked it in with some good ones early on then kept reguritating them year in year out.
The A65 was the closest thing to a new engine that came out of Small Heath which actually worked.
Brand new designs all failed miserably
The scooter range
The Dandy
The Pixie
The Bandit /Fury

Last edited by BSA_WM20; 08/11/17 10:24 am.

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#704607 - 08/11/17 10:28 am Re: B50 chain length? [Re: Tigernuts]  
Joined: Aug 2015
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Andy Higham Online content
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Andy Higham  Online Content
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Posts: 885
Bolton Lancs UK
The Bandit/Fury wasn't really a failure, it was stillborn. BSA/Triumph ran out of money before it could get off the ground


1955 BSA B31 400cc "Stargazer"
1962 Greeves 200cc "Blue Meanie"
1962/67 Greeves 350cc
1967 Greeves 360cc Challenger
1984 Suzuki GSX1100 EFE "Sorcerers Apprentice"
Modified Nu-Trak GM500cc sprint/LSR bike "Deofol"
2003 Aprilia RSV Mille "Lo Stregone"
#704662 - 08/11/17 8:40 pm Re: B50 chain length? [Re: Tigernuts]  
Joined: Sep 2014
Posts: 408
Tigernuts Online content
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Tigernuts  Online Content
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Posts: 408
Naarfuk, UK
OK, have it your way (from experience on this and other forums, I know how pointless it is to bother arguing - not sure why I;m wasting virtual ink typing this actually!). But if either of you have actually seen the insides of a T150/T160/A75 engine, well you wouldn't have written what you have. So obviously you haven't!

106 links is all I need to take away from this discussion, so thanks again to Jon.


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#704700 - 08/12/17 8:28 am Re: B50 chain length? [Re: Andy Higham]  
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BSA_WM20 Online content
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BSA_WM20  Online Content
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Sydney Australia
I have had a very long chat to the owner of a working one down here.
There was not much in the engine that actually worked properly he remade an aweful lot of bits to get the bike to run.
Had they gone into full production BSA would have been bankrupted by the warrany claims.
As mentioned earlier Turner was a brilliant stylist but a garbage engineer.
From memory the published reason was a delay in the sub standard Spanish electrics causing it to miss the USA selling season, but if that was true it would have been relaunched or sent down here where if they all blew up no one would ever know.
But BSA did not do that, they scrapped an entire model after building a production line for it assembling qute a few machines , tooling up to make parts and ordering in thousands of parts.
If you think tha BSA board would throw away all that money when they had captive markets like India, Hong Hong, New Zealand & Australia where they could dump disasters, you have the board very wrong.
All the engineers involved in the project had no faith in the machine, and they say so in their memoirs , money was getting tight and the board took a conservative approach and a massive up front loss.
As for seeing the insides of an A75, why do you think I specifically mentioned the oil pump and the difficulties in preventing it internally hemoraging ?
Don't own one because it is a Triumph in drag but have been inside one or two in my time.

Last edited by BSA_WM20; 08/12/17 8:33 am.

Bike Beesa
Trevor

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