The starter motor on my 81 XS400 is screwy. Pressing the ignition button (which is on the original but some Radio Shack job a previous owner installed), sometimes the starter motor will activate, sometimes it won´t. The previous owner told me that the starter was never good at starting the engine. It turns the engine over but never fast enough/hard enough to get it going. I had it rebuilt: the guy at the shop said a busted seal was what was causing it to drag. Well, the rebuilding didn´t do any good and the starter motor (when it turns on) still isn´t enough to start the bike.