Anyone happen to know the carb specs (jets, slide etc) for a 1951 ZB32 350 fitted with a Conc/Premier carb?
Sparking plug refs would be handy too.
I think that some of the dealers (Burlen/Hitchcock's et al will advise you of the type settings.
As I am sure you know the cams (trials, touring or CLubman), compression ratio and inlet port size and whether you have an air filter as well as exhaust type (straight through, Burgess type or GS twitter type will influence choice.
I would suggest a 928 for a 350, assuming it is GS spec (I use a 930 on my ZB34GS Clubmans head with 1 3/16" inlet tract). The book I have for a '51 ZB32GS shows 1 3/32" choke size for a 10TT9.
Basic setting would be 3 1/2 slide, .106 needle jet, two rings on needle and 25 pilot jet, start of with 240 or 250 main.
As an example I had these settings on my 500 with Burgess silencer, but going to a slightly shorter mini-goldie type silencer from Armours I had to go to 35 pilot to get it to run properly at and just coming off idle, the rest did not change and seems to run pretty well up to legal limit, so far (I took it for MOT appointment 12 miles away and have just received my age related plate so can test it more thoroughly now).
Any help?
Quote from: V500 on 20 Aug, 2025, 11:04 Anyone happen to know the carb specs (jets, slide etc) for a 1951 ZB32 350 fitted with a Conc/Premier carb?
Sparking plug refs would be handy too.
Neil has answered your carb questions. If it is an alloy engine spark plug is a Champion N5C or an NGK BE6S. For an iron engine a Champion L82C or an NGK BH6S.
Quote from: neil1964 on 20 Aug, 2025, 21:43 I would suggest a 928 for a 350, assuming it is GS spec (I use a 930 on my ZB34GS Clubmans head with 1 3/16" inlet tract). The book I have for a '51 ZB32GS shows 1 3/32" choke size for a 10TT9.
Basic setting would be 3 1/2 slide, .106 needle jet, two rings on needle and 25 pilot jet, start of with 240 or 250 n.
A riding mate gave me a nearly new Premier which came fitted to his M21(!) and although the bike starts and runs very well, it is clearly running slightly too rich.
I just needed some sort of ball-park (what does that even mean?) figure to check the spec of the carb before making alterations.
I suspect lowering the needle and reducing the main jet would likely be a good start.
Thanks for those figures.
I usually err on the large side for the main jet and don't touch it again till I have all the other variables sorted out. This is contrary to the usual method which starts with the main jet, but the vast majority of running is done between pilot, cutaway and needle / needle jet. Once these are right the main jet is easy.