MZ/MuZ Riders

mick wrote: Strange if this is from the factory.

It isn't - see also dave47's comment above.
If MZ had used such a resistor they certainly would not have mounted it inside the air box.
What is the resistor connected to, electrically ?

It was not connected to anything, it sat inside the housing without any wires poking through outside of the housing, I found it after talking the housing apart.
I cannot find any description in wiring diagram.

IT CONTROLS CURRENT FLOW USUALLY MAY BE THERE LEFT BEHIND BY A PAST OWNER
LEAVE IT OUT IF NOT FOUND ON ANY DRAWINGS

Thanks for the info on this strange component, I have installed it back in the cover and blocked the two holes up with loctited bolts and used a anaerobic Loctite between the housing halves to seal up the filter housing to give it the best shot at clean air to the engine.