King Quad 300 hard to start

[CACRWLR]

I took my '99 King Quad 300 out this weekend for a shakedown run.  It ran well, except I found that it was a little hard to start.  I've found that for the first, early morning starts, sometimes it fires right up and other times it takes some cranking and then sputters to life (choking it and using the same starting methods each time).  During the day, after running it for a few hours, shutting it down for a couple of hours, and then coming back to it, it was a little bit of a struggle to start it.  Again, it was more of a stumble and sputter to life.  Once it was running, it ran fine though.  One odd thing I did notice that sometimes the cranking sounds a little labored and other times it spins over normally.  Almost like there's some sort of resistance that isn't there sometimes.  Any ideas on what intermittent hard starts might be?  The quad has about 5,500 miles on it.  Do you think a valve adjustment might help?

Thanks.

[Ajmboy]

Have you changed the spark plug and checked your air filter?

[CACRWLR]

The air filter is clean.  I haven't checked the plug, but I'll take a look at it.