Motorcycle Repair: idle and engine heat, yamaha 650 special, wyoming winters

Question
chris, i have a 1980 yamaha 650 special - lent it to my
brother, he left it out for a couple of wyoming winters! I've
got it running again, the carbs took a major cleaning. the
questions i have are: 1- the bike won't idle unless the choke
is on. what do i need to check to fix this? 2- one side of the
engine is running hotter than the other i.e. the one exhaust
pipe and engine is very hot and the other is just warm after
letting it run for a few minutes. is this normal? what can i
do to fix it if it's not normal? thanks

Answer
Hi Rowdy.

What you have described is not normal.

1) The cleaning that you did probably did not get the jets clean enough.  That could be a problem, since it requires a complete disassembly cleaning.  Very delicate work and requires you to have the carbs rejetted properly.  A thorough soaking in carb cleaner may do the trick as well.  There could also be an issue with leaks in the connections to the manifolds from the carbs or to the heads.

2) You could have an issue with the fuel flow to the affected carb or you could have an electrical issue on that side.  possibly a bad coil or a short in that circuit. in addition, you should check the compression as well as the exhaust connection.  Make sure that it is tight.

Start with those and see what you find.
Good luck and ride safe.
FALCON