Hi, I'm new to the forum as I have just purchased my first street bike, a 1986 Yamaha Radian. I'm having a couple of problems that are really giving me a headache.
First, the bike runs fairly well for the first 10-15 mins or so. When you roll on the power it runs slightly rough up until about 5000 rpm, then it cleans out and pulls hard to redline. It runs like this consistently for 10-15 mins, then all of a sudden it starts running only on cylinders 1 and 4. Cylinders 2 and 3 still have spark, but I can unplug them and it has no effect on how it runs. If I unplug 1 or 4 it dies instantly.
Second problem. Should the starter disengage after the engine fires? Sometimes after I shut the engine off I swear I can hear the starter disengage and spin down? After the motor has run for several minutes if I shut it down I can't restart it. It sounds exactly like a weak battery. Sometimes it just doesn't have the power to turn the motor fast enough, sometimes only the solenoid clicks. I have had the battery load tested at two shops and they both say it tests ok. The previous owner also claims the battery is only a year old. The starter is also burning hot to the touch.
Are these two problems somehow related? Almost seems like a heat issue at times. Anyone run into this or steer me in the right direction? Thanks in advance!!!