Doing multiple hill climbs (400 ft sand mt) and on one attempt the bike stalled. Tried to roll it down hill and bump it and nothing. Will kill over just fine. 1.Checked sparkplug by grounding against engine, no spark. 2. Replaced sparkplug, still no spark. Where else should I be looking? The bike is stock, has not had the flywheel removed. My first thought was a new plug cap or CDI. But is there something else to look for, capacitor...?