A10 BSA dual carb head

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A10 BSA dual carb head

Postby HPbyStan » Sat Dec 29, 2007 2:53 am

The often rummored but never seen, by me, dual carb head for the BSA non unit engine is on eBay USA. Auction number, 230206539104. Thing looks brand new in the pics... Stan
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Postby b50root » Sat Dec 29, 2007 10:44 am

nebrer on EBAY
nebrer at skype ( http://www.skype.com )
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Postby minetymenace » Sat Dec 29, 2007 12:25 pm

I thought the twin carb heads had splayed inlets (like the later A65L). This is a parrallel inlet (as the later A65T) to take a two-into-one manifold. This is an aluminium (aluminum) head (used on later machines/Spitfire Scramblers etc) as opposed to a cast iron one. No hard evidence to back this up, just years of observation.....

If there was an A7/10 site of a similar quality to Rickard's B50 site, there would be no arguement!
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Postby Grouty » Sat Dec 29, 2007 12:36 pm

Many many years ago (in my teens !) I had a 650 Road Rocket with an alloy head and twin monoblocs. I cannot remember if they were parallel or not. Just that the bike was a pain, even if you could get it going. No oil leaks when running, but weed all over the floor when stopped. Dad would not let me keep it in the garage :cry:
When it was running it would go like hell. Much quicker than the boys with their Triumphs. Knowing what I know now, I wish I had kept it.
Ahh, if only for hindsight.....
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Postby minetymenace » Sat Dec 29, 2007 12:55 pm

Ah thats it, I think this is a single carb head because the "carb" mounting holes on the head are not horrizontal, but are diagonal thus it is designed for a manifold and single carb. Splayed ports alow for four studs in a row on which to mount the carbs........still just a theory, but I am convincing myself if not others....
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Postby minetymenace » Sat Dec 29, 2007 1:04 pm

OK, I'm wrong... see here, but I have yet to find a twin carb arrangement....
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Postby Costa » Sat Dec 29, 2007 4:19 pm

There never was a "twin-carb" pre-unit head per se. What there was is what you see: an alloy single-carb head, with bolt-on manifold, the removal of which can allow the fitment of twin carbs. Triumph unit 500 twins work(ed) the same way.

Pre-unit Bonnevilles and unit BSA and Triumph sporting 650s got splayed intake ports; nobody else did.

Cheers,

Costa
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Postby minetymenace » Sat Dec 29, 2007 5:09 pm

Yep Costa, basicaly what my link says, it seems there was a speed accessary catalogue in the US only that offered twin carb bits (Carbs and manifold conversion based on the works speed trial bike) for this head, but not in the UK (similar to the Screeming Budgie for your HD)
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