Hi. I’m slowly rebuilding a 1960 Dominator 99. The carb that came with the bike is junk so I’ll be buying a new one from Burlem. My question is whether to replace the carb ‘like for like’ by getting another Monobloc or would it be more sensible to fit a Concentric? Is one ‘better’ than the other (easier to set up, stays in tune better etc). If a Concentric is better, would it be the same bore and jetting as the original Monobloc?
I’m all for keeping things original when it’s sensible to do so, but if there’s a better solution it would seem daft not to take advantage of it.
Concentric is cheaper. That's about it. In theory the slide is better supported in the monobloc, so maybe it might last longer. I'd like to replace my twin concentrics with monobloc because they would then look right.
Concentrics take less space so are more convenient with 2 or 3 carbs. Also less sensitive to sideways forces, so better with a side car. Not your problems I suspect.
Other opinions no doubt exist.
Would not fit a concentric if they were half the price. Cheap nasty and look wrong.
I find the Monobloc easier to work on. Changing the jets (e.g. when optimising the mixture) doesn't involve removing the float chamber first. Also, if you do need to work on the float chamber (e.g. change the float needle to stop flooding) you can assemble everything and then pop on the cover, instead of juggling with the bowl, needle, float, pivot pin in a trough, etc and trying to keep everything in alignment as you feed it back onto the carb, then secure everything with 2 chewed Phillips screws which are difficult to locate.
The Concentric was simpler to manufacture and works better on steep downdraft engines, but is a cheap and nasty device in other respects and seems to wear quicker. .
Hello Mono bloc are far better then any concentic and far easier to tune parts are very go and you get a better throttel response and last longer then any concentric and now Pre Mono bloc is making a come back Yours Anna J
Thanks to all who replied. Looks like the consensus is to go with a Monobloc, so that’s what I’ll be doing.