The 17mm Bing came in the mail today. I did a comparison between it and the 14mm spare I had handy.
The exterior differences are, the obvious 60mm ID air intake, the slightly larger "conning tower", and the clamp to the intake manifold is 3mm larger ID.
Also the fuel port is straight, and they're mirror image. I took them both apart to compare the innards.
The float bowls appear identical and interchangeable. As do the float and valves. The float pin on the 17 seems thinner though.
Although the fuel ports are different, they appear interchangeable as well. The 17 didn't come with the fuel strainer, but one will fit without restricting flow.
The idle screws are different sizes. The jet and atomizer on the 17 did not come with markings. Though they appear to be interchangeable with the regular Bing parts.
The slide needles are the same diameter, but the 17 is 3mm longer. The 17 slide is also slightly larger in OD than the 14.
The choke plates are also different sizes. The push rods for the choke plates appear to be the same diameter, although, the 17 is actually shorter.
The slider spring on the 17 is the same diameter as on the 14, but is slightly shorter with more coils. I can't measure specifically, but the 17 spring seems a bit beefier.
The cover, screws,and gasket are also slightly larger on the 17.
Well, that's probably more info than anyone wanted to know, but here it is anyway.
This 17mm carb will definitely not work with the 15mm intake I have. The OD of the intake is 3mm too small.
I suppose I could shim it, but I think I'll look for one of those larger intakes that bend away from the engine and see if I can find one that will fit better.