But I'm not worried.
The first delay was a simple and understandable mistake -- there are two varieties of the Polini variator kit, and the mechanic ordered variant A, which doesn't fit, instead of variant B, which does.
Yesterday, variant B arrived ... but the results, through various tuning options (springs and weights) either produced no discernible change or negative discernible change, e.g. the RPMs come down but the bike doesn't make the power to get above 45mph. It turns out that in the fine print, that kit is intended for use on a vehicle with a 13-inch wheel. The wheel on the Bulldog is a 12-inch wheel.
So, a couple of things are happening today. One is that another mechanic is going to have a look at things. The other is that a different variator kit will be arriving. It may be done this afternoon.
Why am I not worried? Because this mechanic is dedicated to making the bike do what I'm wanting it to do, rather than just throwing some parts in and calling it "done." I'd hoped to do a 100-mile ride today, but no I'd rather do it tomorrow on a bike that's right than today on a bike that isn't.