Vertical spikes, or lines on the graph, are electronic "noise". This happens when something other that the sensor induces a flow of electrons into the sensor wire.  The cause of this could be external, such as a electric motor, or a welder running near by; or it could be internal, such as a bad ground in the machine, or power into the machine. If the noise is small, you can use the Smoothing option in preference (F12) to remove it from the display. Always smooth all channels the same and never use more than 5 points of smoothing.

1 - Check for any equipment that might be causing the problem, such as A/C units or even florescent lights. Try running the dyno with other devices turned off.

2 - Try running the dyno with the electronics power supply (small plug) plugged into a different outlet from another part of the building.

3 - Install a ground wire from the dyno frame to conduit or a good ground.

If none of this helps contact REI tech support for assistance.