A graphite lube made for locks would be a better choice. I doubt it would have any adverse effects if some made it into the fuel, but you don't need to use much for it to work.
WD-40 doesn't last longer as a lube anyhow.
AKA: Tim & 'The Adventure Cycle' VROC #24567, NEVROC, SteelCity VROC
"When life throws you curves,
Aim for the apex."