Motorcycle Repair: carburetors, yamaha seca 600, highway speed

Question
  Chris,
    I have a 1992 Yamaha seca 600 and my buddy
cleaned the carbs but it will not run without the
choke being on. It will run at highway speed but
surges and will not idel without choke on.
    Any help you can give will help. I still
think its the carbs.

                            Thank you,
                           Wendell  

Answer
Hi Wendell.
 Start by checking the plugs.  Are they clean or blackened or whitened?  That will tell a lot about whether you are running rich, lean or good.  At least as far as your mixture.  There could be problems with the carbs........worn or torn rubbers internally, synchronization could be off, floats not working correctly, etc.

How did your buddy clean out the carbs?  Did he take them apart and soak them and clean (like with a brush) the internals and blow out and clear the ports or did he just pull them off and spray them out and scrub what was easilly accessible.  The former would indicate that it could be something other than a clog in the carbs, the later would mean that there is still a possibility of something in them being clogged or dirty.

Have you checked the fuel for water?

How about the valves and timing?  Valve gap and setting proceedures are in the repair manual.

Start with those and let me know what you find.

Good luck.
FALCON