EUROJulian
Husqvarna
A Class
hmmm- I'm not so sure that this is such a great mystery. First of all, these motors (xlites especially) are known for the ADC not working if the valves are on the loose side of the specification. Second of all- they start and run fine at low rpm's with the ADC working... so why not at high rpm's? It's not like the ADC is letting the majority of the compressed mixture pass by... I'd guess (*guess*)...........!
Not a mystery. I was pointing to guy riding 200cc bike or maybe less, for all that time not realizing it.
On the other hand if that was all he knew since bike was new and had no exposure to other motorcycles in this class.... I would expect some other giveaways though....