Amal Concentric swap 1960 GF

[morris]

In my experience it's a fit, adjust and forget.
I installed a brand new 389/45 early 2013 on the '58 SA. Since then more than 4000 troublefree miles.
In the beginning there was a slight fuel weep at the bottom where the jets screw in, but that cured itself.
Regarding the polishing, I wouldn't do anything. It will develop a lovely greyish patina if left alone.
OTOH, the concentric 900 that came with the '52 plunger is also behaving flawlessly though, so

[tlmark]

I have decided not to polish it.
 
there are two reason for to swap back to mono first is the carburetion doesn't seem right looking at the plugs
plus it returns it to the stock look. 

[edboy]

my plunger a10 has a concentric 928 and i m having a similar problem with richness. it starts and runs lovely but really needs a smaller pilot jet. i wondered if a different slide size would affect the pilot setting or whether to buy a premier carb instead. yes all jets are clear.

[muskrat]

G'day Ed.
Does your 928 have the pressed in pilot jet or the removable one in the body above the float chamber? The later carbs with the pressed in pilot still have the thread for the replaceable ones so you can drill the pressed in one and use replaceables to richen or leave it and screw in a smaller leaner one in the bowl. Don't try to rectify the problem with the slide cut away.
Cheers

[edboy]

hi muskrat,
yes to all you mention i will give it a go .

[RDfella]

Agree with what Rocket Racer says.
I never liked concentrics - found them fragile and prone to leaks. The Mk 1 1/2 was marginally better, but the Mk2 was another pigs ear (in my view). Something cheap and nasty about them and obviously built down to a price. Although (in theory at least) the float chamber was better situated, in reality that only made a difference for those with sidecars. I always preferred monoblocs, and when they didn't go big enough, I used Bing.
A point often overlooked by people considering carb sizes, is that the overall capacity of the engine is not the criteria - it is rather the capacity of each cylinder. Same goes for the exhaust. If a 500 single has a 1 3/4" exhaust, then a 1,000cc twin will be the same (or maybe 1/8" bigger). So let's not forget we're feeding 325cc on an A10 / A65 etc. and, unless we're holding 6,000 rpm most of the time, an 1 1/8" carb is plenty big enough. 1 1/16" would actually give better pickup / acceleration.