Single MKII Amal / Atlas

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May 6, 2010
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I'm wondering if anyone has any previous experience with running a single MKII Amal on an Atlas.
I've been running the VM34 Mikuni on it for a while (that's what was mounted when I bought it).
But I've since rebuilt a 34mm MKII Amal that I'm planning to mount.
Basically just wondering if anyone has any experience / advice for me to use as a base line starting point while I start to tune it.
Thanks
Jeff
 
When I was at N-V, there was some testing done on a single Monobloc carb on the 650SS I rode to and from work. IIRC, the end result was that the single carb gave improved low-RPM torque but reduced top-end power a bit. The tests were instigated to deflect criticism from the sidecar community that the new Commando couldn't pull a chair. I think the concept woule apply equally to the Atlas - more bottom-end torque but less top end power.

After coming to the US and finding out about multi-barrel carbs, I couldn't understand the British fetish for multiple carbs. I once had an MG-1100 sedan (an early rendition of what became the Austin America). It had an 1100cc eng9ine with twin SU carbs. The carb throats weren't much bigger than my thumb, and the inter-carb linkage would have warmed Rube Goldberg's heart. I took them off to do some cylinder head work and was very careful to tie them together with bailing wire so as not to lose any parts or have to figure out hoe to reassemble them.
 
Norton did fit a few Military/police Atlas bikes with single monoblock carb, as was mine, when I obtained it, as it was ex-police. There was lower down power enabling the bike to drop/run about 5mph lower in top gear than with the twin carb setup, but top speed felt strangled, when I converted to twin carb setup, I found a port reducing sleeve in each inlet port of the head, this was to speed up the gas flow at low revs.
 
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