Is the accelerator pump leaking? That's odd that it's not working now, but carb sprays are heavy in xylene, which will aggravate a weak rubber part. Even so, it won't make it run bad, only a possible slight off-idle hesitation. You DID use a spray cleaner, yes?

 

Yup, definitely used a spray (http://www.canadiantire.ca/en/pdp/mo...-0380720p.html). The label on the can does not mention it will harm plastics/rubbers. I'm starting to think I may be overthinking this whole thing (like I say, I'm a noob).

I don't think the carb cleaner ruined the accelerator pump diaphragm, but that it was just old (bike is a 2000 WG). It is all cracked. I called HD to check out the price on a replacement, and the first thing the guy said was, "Yup, those dry out an crack all the time when they're old", so I'm guessing its just normal wear and tear.

Funny thing is that the bike was running fine. Maybe it (the diaphragm) was just on its last legs.