use a curved mount
clean helmet with some grease remover
(white spirit or acetone will probably damage/remove the lacquer but sticking the mount straight onto the plastic will make a much stronger bond than sticking it onto the lacquer )
^^you can also take a fine sandpaper and sand the spot down a bit ...
then apply the mount @ room temperature
after applying let it sit for a day before using it ( push it on regularly)
i've been using my gopro for around a year now and i even use it on airbags where you land on your head quite often :D, and it's hanging in fine !
Belgium represent !
"The windows are vertical how am i going to poop on those?"-Killabees
"God isn't black, you fucking moron!"-Shibby
"I shit rainbows and sneeze glitter."-Arabian