My WR450F has over 220 hours on it, but still runs strong, yet now I have starting issues. One year ago I replaced the original YUASA battery 6.3 Ah for another one (also Yuasa 6.3aH). I always connect it to a battery tender but it seemed that the battery lately has lost substantial energy, whic surprised me as the battery was fairly new. The cost for a new one OEM battrey in Brazil is ($300) believe it or not. Friends of mine that ride Honda 450s has successfully changed their batteries for OEM 5Ah, batteries so I followed their advise and bought an OEM Honda battery, that has the same size, but only slightly less power 5.0Ah vs 6.3Ah. The battery was activated yestyerday, but when I connected it, unfortunately the bike continues almost impossible to start (clearly lacking power to turn the cranckshaft at sufficient rpm) not as a result of poor jetting, my bike kickstarts easily. QUESTION: does anyone have experience with a good 5Ah on a WR450F? Does this work? Or are my brushes of the starting engine worn? Please help, I have a race this weekend and would like to get my bike ready.