OK, absolutely basic stuff then. What is the oil level? Check when warm, engine stopped for a couple of minutes, bike held upright, dipstick resting on the threads NOT screwed in, should be between the marks. What oil is it using? When was it last changed?   Have you checked the battery terminals are tight? Sounds silly but loose terminals can upset the voltage which the system might not like. Probably not this though. Is the bttery in good condition and is the charging