i have a 2005 yamaha 1200 xlt. yesterday it was running fine and then just sputtered and died at 3/4 throttle. checked compression today. no compression cyl. 1, 2& 3 are ok. any ideas?
on that model, i'd look for a oil line that came off or a clogged fuel filter inside the carb on #1. since the carbs are hard to get to, they often get ignored and its really hard to see the oil lines with the exhaust in place. that model has a 3 separate jugs so you can replace just one jug. figure out the problem before you replace the jug/piston or you'll likely have the same result.
could be anything from bad head gasket, to the piston melted due to a lean condition to a broken connecting rod. pull the plug and look at the plug. if its covered in aluminum, your piston is toast. if you can look down the spark plug holes, you may want to do that too.
