JH600 stalling

[998S]

But I don't agree about trying to block the air inlet to the enging - there will only be an effect with higher rpm and the stalling happens below 2000 rmp...or.....??

Well, I don't completely agree with you :-)
It is surely not the solution, and as indicated, it might result in a power loss or stumble at higher rpm's, but you should be able to notice a richer mixture.
Best is to block a part of the inlet channel (inside the throttle body), if not poassible, then the filter, if not possible then the airbox intake.
For the JH600 the last option seems to be the only one without too much work.

Again, not an solution, just a check if it changes something in the behaviour, after which to remove the tape quickly...
Thanks for your thinking with us though, every suggestion is appreciated, specially if it is some thinking out of the box...

E.