Thanks for all the info guys. Appreciated.
Kris01:
It was the right bolt & my drain pan got filled with about 1,5l
of old oil. About the brass plug on the idle mix screw, it's still there.
I performed the draining with the bike sitting on the stand though,
maybe I should have tried to lean it in the other direction at some
point.
Dave:
Will try with fresh fuel. Wouldn't have imagined fresh fuel
to make a lot of difference after two months so thanks for the
hint. About the old plug, yeah, I took it out after changing oil/filter
and noticing the bike stalling under the described conditions. This
was also after the 2 months of storage, before that I think I drove
the bike for about 1k km. The deposits in the sparkplug itself though
look quite stiff and solid, like if they were old enough to think the rich
condition has been there for a while. But my ignorance should be
factored on all these conclusions
Few questions for everyone:
Whats TEV and E10?
What kind of external tachometer would I need to adjust the idle
speed if I wanted to be 100% accurate? Are there any other
formulas to perform this without a proper tool in addition to the
10mph idle speed at first gear that serowbot mentioned?
Still thinking about the old filter, has anyone experienced similar
problems with a bad filter? What are the symptoms you'd expect
to see/ear if the filter was the one at fault? Is there any way to test
the filter for correct operation?
Is there any easy way to perform a light cleanup work on the carb
without disassembling it fully?
Thanks again for all your help guys.