QuestionMark, I bought a suzuki katana 600 which will drive for a few blocks or so and then it begins to spit and sputter and evetually dies and is extremly hard to start back up. I have replaced all of the basics. I have pulled the plugs several; times and they seem to be running rich with black carbon build up. dont have any history on the bike. Im sure it ran good at some point. it has 14667 miles. I am stuck. is it the carbs or coils. when its cold it runs ok but idles funny, hesitation on take off and then after warming up it begins to die. Please help if you can.
AnswerHi Scott,
You've read the spark plugs; black/sooty indicates an excessively rich air-fuel mixture. Check for intake air restrictions.
Check cylinder compression to learn the sealing properties of the combustion chambers (condition of the engine). Perform a leak down test if necessary.
Check valve clearances and adjust accordingly.
Compression and valve clearances must be within specifications for the carburetors to work properly.
Check carburetor synchronization.
Depending upon the above results, I would remove the carburetors, partially disassemble and inspect.
Measure float heights/fuel service limits.
Check for evidence of fuel contamination and varnishing.
Check carb and fuel tank ventilation hoses and vents.
Check fuel and vacuum hoses for varnishing and pinching or collapsing.
Check petcock for varnishing.
Perform electrical diagnosis to verify the integrity of the ignition coil windings. Check secondary coil leads and plug caps.
Lots of things to check to learn the source of the problem.
Keep me advised on your progress. I return tech information files by email. Remember to include your email address with question as requested.
Respectfully,
Mark Shively
