my sister had a 70's honda civic with the same hondamatic semi auto. it spat the dummy, (literally a big shot of oil hit the house one day , and im sure it was because she just used D all the time. i gave up telling her to use L first..
you COULD start of in d- but it seemed to put alot more stress on the car ..and obviously slower acceleration.
maybe not as noticable on the lighter bike. in my mind its better start in L