Bike hard to start when warm??

[Spartiatis]

I have a 1997 Cr250 R. Its starts first or second kick when cold. But yesterday while riding I was having a hell of a time starting it.
What could be the problem?? Spark plug?? :whoa:

 

[Matt90GT]

change the spark plug. Check the compression.

Also clean the carb, especially the pilot jet and set the float level.

 

[truckster225]

Do a compression check while its hot. See if it drops to below 100psi or so. If it does it may be time for new rings.

The same problem happened on my old Suzuki.