I don't know as much as CBRD obviously sounds like he does but when I bought mine, whilst it seemed to run ok (bearing in mind I was still wary of letting it fly) I came to the conclusion that my carbs had been tampered with and probably Dyno jetted.
My main problem was fuel consumption, I was only getting 7m/litre. This also showed itself by 'sooting up' the rear face of the exhaust pipe.
As I had read that as part of the Dyno jetting process involved drilling something, then that was probably irreversible, I bought a second hand set off fleabay. Instantly 8.5m/litre.
You put your location down as UK, is there nobody local that you could coerce into letting you try theirs on yours for an hour?