BSA + Rotax. So far = This

Honeysucklekisser
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BSA + Rotax. So far = This

Post by Honeysucklekisser » Sat Nov 21, 2015 9:23 pm

Hi All.
Slowly making progress with this but need to decide on front sprocket size before I can go much further. 1971 BSA B25 frame with 500 motor. Engine will go to sportax for rebuild and leccy start once all the welding is done. Engine is a 500 with flowed head, 670 cam and should get a HC piston in the rebuild. Front end is only temp as brake is rubbish so will use Betor front fork and brake from a Can Am. Can anybody help with any thoughts on a starting point for the front sprocket? Thanks HSK
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deadgrass.
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Re: BSA + Rotax. So far = This

Post by deadgrass. » Sat Nov 21, 2015 10:35 pm

depends on what you intend to use the bike for .
also what back sprocket you intend to use.
also what sise back wheel in use .
also rear tyre section.
do you want response [off roading] or relaxed [touring on road]?
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thank god for atheism.
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Honeysucklekisser
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Joined: Sat Jul 11, 2015 12:19 pm
Location: Bedfordshire

Re: BSA + Rotax. So far = This

Post by Honeysucklekisser » Sun Nov 22, 2015 8:47 am

Thanks for the response. The bike will be a road bike and have a choice of 47 or 52 for the rear sprocket. Rear wheel is 18" inch and tyre 4.00 x 18 trials type. Before the motor is finally welded in just want to make sure chain run and sprocket height is right. The bike is very light and I have no experience of the 500 rotax motor in a lightweight chassis. Thanks HSK
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sparky
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Re: BSA + Rotax. So far = This

Post by sparky » Sun Nov 22, 2015 11:06 am

Perhaps have a look at the Harris Matchless specs here:
http://www.motorbikespecs.net/index.dyn ... =Matchless

Similar engine and weight, uses 20T front and 46T rear with 18" rear wheel. Looks an interesting project! Hope you keep us up to date with photos.
Cheers Dave
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1994 MT350
1960 AJS model 20
1960 Matchless 650 CSR
1999 BMW F650ST

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frenchy3
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Location: snetterton,norfolk

Re: BSA + Rotax. So far = This

Post by frenchy3 » Sun Nov 22, 2015 11:22 am

Nice concept,the style of an old British bike with the reliability and indestructible nature of the Rotax engine.The Rotax still looks dated and like it should be in an old bike. I have lost count of the times i have been asked if my MT350 is world war two vintage!
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MT 350 1996 The Albatross

mick

Re: BSA + Rotax. So far = This

Post by mick » Sun Nov 22, 2015 8:26 pm

Excellent project and not as divorced from potential historical reality (if you see what I mean!) in that it was, as we all know, the 500cc BSA single motor that Alan Clews used to build his first CCm moto X bikes as power for. Bore and stroke are different in that the BSA was 84 x 90mm and Rotax is 89 x 77.4mm.

it makes you wonder if this is what BSA would have been making 10 years after their demise.....

Look forward to hearing more about progress and it's final completion.

Mick
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gegdonnell
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Location: North East Wales

Re: BSA + Rotax. So far = This

Post by gegdonnell » Wed Dec 02, 2015 10:26 pm

Nice project, have been looking at the BSA B40 and toying with the idea of getting one or something bigger. I remember the BSA Victor and the Cheney BSA in my youth, and dreamt of owning one. Good luck with your project.
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Minter
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Re: BSA + Rotax. So far = This

Post by Minter » Sun Dec 06, 2015 11:20 am

Great looking project, cant wiat to see it!

Id go for either 16 47 or 17 47 on the gearing...

HTH

:D :D
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Honeysucklekisser
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Joined: Sat Jul 11, 2015 12:19 pm
Location: Bedfordshire

Re: BSA + Rotax. So far = This

Post by Honeysucklekisser » Sun Dec 06, 2015 8:51 pm

Good evening and thanks for the comments and encouragement.
I will go with the 17/47 option and see from there. More pics to follow. Regards HSK
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Honeysucklekisser
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Location: Bedfordshire

Re: BSA + Rotax. So far = This

Post by Honeysucklekisser » Tue Dec 22, 2015 10:37 am

Hi Gents.

Starting to look like a bike now. Not sure about the colour though.

HSK
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