hi iv been trying to restore a 1980 Honda XL80 weird problem?

[DeVoNXLZ]

the ignition system is set to the f mark on the magneto when the exact moment the points open making correct spark timing it starts works idles as soon as i give it throttle or even leave it idling it looses spark when i try to take the magneto off its always a little stuck only after it looses spark though. the key is good its always lined up with the crank shaft and f corresponding indication on the magneto i dont think its shorting but maby in some weird way the wires look well insulated could it be the condenser shorting its weird OLD Honda's last forever DeVoN