Timing gun

I have an old Snap On (80s) timing gun, and tri spark electronic ignition which I want to check.
The timing gun has a dial on it to dial in 28 degrees.
Should I dial in the 28 degrees on the gun or set it at zero.
I have set the timing statically and the bike runs.
Thanks in advance.

Ratboiler said:

Should I dial in the 28 degrees on the gun or set it at zero.

Click to expand...

= Zero.

Ive just bought an "advanced" gun with a similar adjustment. The way these work is they introduce a delay in the flash rate according to what you set them at. So if you had gun set at 28 deg, the timing flash will be going off 28 degrees later than ign triggering point. This has the affect of getting timing mark on alt to appear at zero deg, ie TDC, on the primary cover scale. Yet spark is actually timed to 28 deg. This is useful to allow accurate readings where the bike or cars scale does not extend to. You only need to have the TDC mark on the scale. Then set gun to what advance you want and adjust ign timing until flash shows TDC on scale. You can also determine what current timing is by adjust gun to bring flash to read TDC mark. Then you get reading off gun dial.