Well, I'm fairly sure it has improved things. Quite noticeably.

The main improvement so far seems to be when it's cold. Previously, changes on a cold box were klonky at best. Now cold changes are good enough that I don't even think about them

Hot changes haven't improved to the same degree, but they have improved. Upward changes are now good enough that I don't think much about them, just change like on a normal gearbox.Second to third was always worst, and still is, but I have to get things quite badly wrong to get more than a snick - felt but not heard.

Down changes are still not so good. Fifth to fourth was always fine. Fourth to third which used to be problematic is now usually fine, and at worst a mild gronnnk. But it's not good enough that I can change without thinking about it.

Third to second is quite good now , though this is usually only a "traffic stop" change (pretty flat torque curve) . Second to first is such a big jump that I think it will always need to be carefully timed, this is more of a factor of the gear ratios than anything else.

I won't make a final judgement until I've tried fanging it on some decently twisty roads, with a few hairpins (which won't be until there is some decent weather). But at this stage I'd say it has been worthwhile

I found the Blackwoods-Paykel part info . I got mine from the Wiri branch but any Blackwoods-Paykel branch should be able to get it. They'll have to order it in specially from the NZ distributors, who will claim that it doesn't exist, so they'll have to argue that through. The NZ distributors will probably have to indent it from Australia who in turn will need to indent it from the USA, takes a couple of months.

B-P part no is 04224352. Description "LUBRICANT MOLYKOTE M-55 PLUS 1LT 2194923". Vendor is 1BEA15. List price is $69.14 + GST, I got a 30% discount which I think anyone can get (the "list price" is a fake for dealers to mark up), = $48.40 + GST = $54.45 for 1 litre.

Which is pricey, but you only need 5% to 10% (10% for extreme situations, they say, I used 10% which was probably overkill) so it goes a long way. About $5 per gearbox + final drive change, which is not big deal.

NB They may try to sell you Molykote M55 . THIS IS THE WRONG THING. It is an Oring grease, comes in a tube . WRONG You need Molykote M-55 PLUS . Which comes in a 1 litre can, looks like very dirty oil. (Yes, it is a damn confusing part numbering system. That's Yanks for you) .

I'd still have to say it's the worst gearbox I've ever used, by far. But it is an improvement. And upward changes are now good enough that I'd say they were (just) acceptable.

If anyone want's to try it, PM me and I'll send you 50ml which would be enough for a gearbox oil change (I'm assuming airhead gearbox oil capacity is about the same as the K series, which is 850cc)

[Incidentally, how come there is a "Tweaking and Tuning" thread for cruisers, sportsbikes, and off roaders, but not for ordinary bikes ?. Oh well, never mind]