Electromagnet interference with motorcycle
You are assuming that the sensor in the road detects a magnet (it doesn't), or that it detects ferrous metals like iron (also, negative).

A 20 kg electromagnet might make it easier for your bike to trigger the sensor, but not because it is an electromagnet-- because you have added 20 kg of metal to your bike.

Here is a nice web page that talks about road sensor designs and how you might get your bike to be more easily sensed.  Essentially, you place your bike in strategic locations on the sensor or buy a car.  One note about that page:  it talks about mounting permanent or electro-magnets to your bike, but that won't work well if at all.  Positioning your bike is much more effective.