Timing Light

[dwaynemcfarlane]

hey guys.
So i have just finished reassembled my 77 xs 650 engine. Wauw what a ride and when i got the engine fired up, i was as happy as can be!
Anyways - the timing.
I run with a Boyer Bransden Electronic ignition and a Vape Power Dynamo generator and about to buy a timing gun.
Please walk me through this in steps, how do i use the timing gun and what should i be aware of.

Sincerly D

 

[Paul Sutton]

The timing gun will have a means to connect to the spark plug or the HT lead. Then the ignition fires a signal from either the spark plug or the HT Lead is used to fire the light on the timing gun. When this light is directed at the alternator rotor the light will strobe and make the rotor appear to be stationary.

On the XS alternator with points ignition there are three marks on the stator: TDC, Idle and Full advance. On the Rotor is a mark which lines up with the stator TDC mark when the pistons are at TDC.

If the engine is running from about 3500 rpm and higher the engine timing should be at full advance. When the timing gun flashes this will strobe the alternator and make the rotor mark line up with the Full advance mark on the stator. If the timing is out these marks will not line up so you must adjust the timing.

Adjusting the timing on a points engine involves physically moving/rotating the points to make the ignition fire sooner or later. You make this adjustment with the engine running at 3500 rpm or higher and attempt to get the rotor mark to align with the stator full advance mark. On the Boyer instead of adjusting points you physically rotate the circuit board with the pickup coils on it.

I do not want to go into too much detail here, just give you a basic idea. You should view some UTube videos to see what my description means in practice.

Have fun.

 

[Paul Sutton]

I suggest you have a look at the following video made by TwoManyXS1Bs. Although he is using an onboard DIY LED timing light you will find the video interesting as it shows the timing marks and how the rotor mark in white moves towards the Full Advance mark on the stator as the engine revs up:

You may notice that the full advance mark never lined up fully with the rotor mark. This is not an error but a deliberate alteration to the timing made by Twomany for his own riding requirements. But, usually this misalignment would indicate the points need adjusting.

 

[dwaynemcfarlane]

Thx guys!!!