Motorcycle Repair: hard to start, automobile mechanic, automotive mechanics

Question
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Followup To
Question -
I bought an 03 Yamaha Breeze for my daughter and it ran graet for the first year.  But half-way through this season it became really hard to start, hot or cold.  I tried cleaning all the jets in the carb but that didn't help.  I don't know what else to do.  Please help.
Answer -
Hi John.
 Have you checked the electrical system (wiring, battery, charging system)?  Check the battery with multimeter and hygrometer.  A bad cell would produce voltage, but insufficient amps to start the bike.

 Make sure that you are getting spark at the plug as well.

Start there and let me know what you find.  We can continue from there if need be.
Good luck.
FALCON

I have checked the spark and it is a crisp bright blue.  It will start I just have to crank it for 3 or 4 minutes.  Sometimes I have to use a battery charger but it still has to crank for 3 or 4 minutes.  Any more ideas.  
P.S. I am an automobile mechanic

Answer
Hi John.
 Have you checked the timing and valves?  They could be out of adjustment.  Also, something struck me.  You said that it started giving you troublethis "season".  Did the bike sit in winter storage?  If it did, then the carb needs a thorough cleaning.  It probably is gummed up with varnish from the old fuel.  You will also want to dump any fuel from last year and clean out the tank or reseal it.

 I know that a lot of automotive mechanics are oftentimes stumped by bikes.  I was at first. My initial training was as an automotive mechanic in the Army, so I know where you are coming from on this, but a motorcycle engine is basically the same as a car, with only technical differences that you can find in the repair manual.  The basics don't really change much, if at all.

let me know what happens.
Good luck.
FALCON