Flap chokes work in half open positions and 3/4 open positions with the throttle getting twisted -- all carbs used to be that way. You learn how far to close it to get it going, then you had a more open partial position you dropped down to for the first block or so on cold days. Then you knocked it open all the way. My Hondas all had Keihin carbs on them and they all did OK for me, gang carbs with linked chokes operated by a lever (like this one looks to have).
Dunno, looks like an accelerator pump there on the side. You can read Keihin on the carb though if you look good at all the pics.
I don't know enough about big Keihin carbs to have all that much of an opinion, but I look at these and think big Hurley jugs as what else is there out there that needs a carb that big? Mebbe a big V-twin Yamaha or Big V-twin something or another?
It is a direct copy of somebody's carb, or they are building them for somebody and simply leaked out a couple of thousand into the wild "accidentally" ..... you know them Chinese will do stuff like that.
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Anyway, the idea is to find a Chinese rip off of a 36-38mm VM carb if such is available. Or find out what is available that could be coaxed to work correctly at a low low purchase cost so as to make buying $140 slides and such unnecessary.
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Anyhow here is your carb and who is actually making it in China and selling it on Amazon for $48 all day long.
http://super-spare-parts.en.alibaba.com/product/614191687-214116286/JingKe_PZ...http://yitonmoto.en.alibaba.com/product/475997476-212685209/Carburetor_PZ30_w...