Carbs were dirty,cleaned carbs,balanced carbs,motor idles ok & runs up to high speed great.Throttling back it will stall.Throttle back slowly it might stay running ok.thanks ahead.
how did you balance the carbs with no manual.
it is adjustable but you MUST follow the correct procedure.
you MUST use a tech mate vacumate or similar 4 channel manometer to sync the carbs.}
did you drill and remove the idle air fuel mixture plugs.
this set up is very very touchy and MUST be adjusted as per the manual or it simply doesnt work well.
buy the correct YAMAHA service manual and follow the steps and it works.
seloc and clymer simply wont work.