If the check engine light comes on switch the bike off and then turn the ignition on and do not start the bike, after a few seconds the check engine light should flash. Count the flashes and then look for the trouble code listed. Mine turned out to be a crank position sensor. There are long flashes and short flashes each correspond to a number and a code along with a brief description of what is causing the trouble. I dont remember if the codes remain if the engine runs ok but its worth a try. Slow starting is something worth worrying about since the likely hood of getting stranded is small, its nice to to make sure.
This article should be the correct flash codes.
http://www.awingaway.co.uk/GL1800%20FI%20Codes.pdf