Motorcycle Repair: Spark problem, valve clearances, wiring harness

Question
QUESTION: I know u said u only do certain models but maybe u can help.My bike starts and when the motor is hot it loses spark.Ive changed the battery,rectifier regulator,pick ups,cdi,wiring harness and still experiencing the same problem

ANSWER: Are you sure it loses spark?  Is the length of time it takes always similar, or does it change from when it works to where it stops, and how long does it run for?  If you've changed all the parts above the only things left are the coil and the plug, and the capacitor on the ignition circuit.  Let me know if those have been changed.  Jan

---------- FOLLOW-UP ----------

QUESTION: Hi thanx for your respose.The plugs are newish.The bike had a full service and ran for about 500km before this problem started.I have changed the coils.I will check the cap on the ignition circuit.Will let you know if that worked.Thanx again for your help

Answer
I don't know what type of bike this is, but when things get hot they expand.  Perhaps valves are sitting off when they get hot, resulting in a loss of compression.  Did the valve clearances get checked at the last service?  If so I'd re-check them.  Unless you're sure it's ignition, you did not mention the condenser?

Good luck,  Jan