Have a 98 Honda 450 foreman - no fire to plug checked coil plug cdi box and switch all are good any ideas what could be wrong?

It really sounds like a kill switch or safety interlock issue.

When the kill switch is malfunctioning the coil is grounded and will not generate a spark.

Do a continuity test on the switch contacts or wires, if there is continuity with the switch in the run position the switch is not functioning, or the wire has gone to ground somewhere.