QuestionThe bike will not stay in idle once warmed up. I have replaced the petcock and have adjusted the throttle and idle needle. The battery has also been replaced and changed out the oil due to fuel flooding in the air box. Still stuck on what to do next. Thanks!
AnswerHi James,
There are a few things that can cause
this stalling on older Yamahas.
First things to check (as you have been doing) are the basics.
-Clean/soak the carbs and idle jets thoroughly, these gum up easily.
-Check float levels or fuel height in the bowls.
-Use a good battery.
-Check petcock vacuum diaphragm.
-Check carb diaphragms for pinholes.
-Check for vacuum/air leaks on the carb intake tubes.(Use carb spray)
-Try turning the idle mixture screws out another turn from 2.5 to 3.5 turns.
This will richen the idle fuel mixture.
-Check that all cylinders are running, check pipe heat and compression.
-Always use fresh fuel and check your spark plug colors
for clues on what is happening inside the combustion chambers.
http://verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm
Now for the last but not least problem on old XJ and Virago's:
Check the (TCI) transistor ignition box for cold or poor solder joints.
Many of these boxes were either badly soldered or the
heat caused them to break. This causes instant stalling.
Here is a web page link that describes that problem
and what you can do or have an electronics expert do
to solve this:
http://members.tripod.com/dave_jack/id41.htm
Remember to eliminate all the common possibilities first
but many of these transistor boxes are now failing from their
age.
Good luck with it,
Wayne S.
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