I’m not a carb expert. I can strip, clean and tune my own carbs fine but if I was relying on my powers of fine tuning for a living I’d be in trouble. It’s just as well the original CV carbs are fairly straight forward.
Many of their problems are related to dirty tanks leading to blocked Pilot circuits, float valve, float level setting, airleaks in vacuum barbs, boots, butterfly shaft or air filter.
Good discussions of these have come out of the Garage.
Mikuni_BS-CV_Carburetor_Rebuild_Tutorial … a nice pictorial guide
Here is a Mikuni VM manual
Interesting read on CV carb setting up
jet crossover
2 types of original carbs, both CV, see the Oz site too
- BS38 – early types were not linked and bolted perpendicular to the head, later models were linked and the boots were angled to the head
- BS34 – linked and angled to the head
Basic CV carb ID pics
US XS650 carb guide
pilot jets
float setting
CV cut-away
CV schematic … BS34 pilot jets are fed directly from the main so must be plugged
VM dimensions
Goran Perssons vacuum port mod
This is handy for providing vacuum points to balance your carbs if using boots without vacuum barbs, simply plug when not being used.
thexscafe 
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