static timing

[Killer Canary]

Hello!
I just bought a '78 gs 750 that I am trying to get running. Compression, 1-4, is 150,150,55 and 150. So far, I've thoroughly cleaned the carbs, installed new plugs and points, set gaps, checked for and found 12V at coils; the starter clutch only engages every now and then( fix it when I figure out how to get the rotor off),but when the engine turns over, all I get is the occasional back-fire. I can tell it's been ****ed around with plenty by PO, so can anyone tell me how to static set the timing?
Thanks in advance.

 

[earlfor]

I had just posted this in a tech thread a couple threads previous to your question.

Here's a copy.

To adjust timing with the bike running, you need a dynamic timing light. to set the static timing (bike is NOT running) all you need is a 12 volt lightbulb and two wires so you can connect it.

Here's the proceedure for timing the 750. The points are located under
the round cover on the right end of the crankcase/crankshaft.

The round 6" plate that both sets of points are mounted on (breaker
plate) is held in place by three screws located at 12, 4 and 8 oclock.
Loosen the 3 screws on the breaker plate. Note that the screw at 12
oclock is in a slot. Rotate the breaker plate until the 12 oclock screw
is centered in the slot. Tighten the three screws.

We will replace the left side set of points first (located at 9 oclock
position) These are the points for cylinders 1 and 4.

Take a 19 mm wrench and rotate crankshaft until points are at widest
gap. Unscrew hold down screw on pointset and remove points. Note the
white wire that goes to the pointset and the placement of the insulator.
The insulator must be correct or the points will be grounded out and
will not work. Put the new points onto the breaker plate, set the gap to
14 thousandths, and lightly tighten the hold down screw. Install white wire.
Rotate crankshaft once again with 19mm wrench until points are at widest
gap. Check that widest gap remains at 14 thousandths. Adjust and
retighten holddown screw if needed.

Rotate crankshaft until rightside points are at widest gap (for
cylinders 2 and 3) Remove old points and install new points and set gap
at 14 thousandths. Note insulators on black wire installation. Rotate
crankshaft with 19 mm wrench again stopping at widest gap. Recheck gap
as you did with the left pointset. Adjust and retighten hold down screw
on points if needed.

THE ABOVE COVERS SETTING THE POINTS GAPS




Next is the timing:

Timing for cylinders 1 and 4 (the left set of points)....................
With 19 mm wrench, rotate crankshaft while looking through the timing
window and align the mark that looks like |F1 with the timing mark on
the engine case.
(the line (|) preceeding F1 is the mark |F1

note: some bikes will have a stationary timing mark on the engine case
and some will have a mark on a stationary timing plate that can be seen
through the timing window)

Connect a continuity lights wire lead/clip to the white wire clip on the
left pointset. Clamp continuity light probe tip to ground on the bike or
battery negative terminal.

Turn ignition switch to on (do not attempt to start bike, just switch
ignition to on)

The continuity light should be on.

Loosen the three screws on the breaker plate located at 12, 4 and 8
oclock. Rotate breaker plate until continuity light just flickers out.
Retighten the 12, 4, and 8 oclock screws on the breaker plate.

Unclip continuity lead from left pointset.



For the Right pointset
Rotate crankshaft with wrench until you see the timing mark F2| become
aligned with the stationary timing mark on the engine case.
Connect continuity light lead to black wire on right pointset.
The ignition should be switched on and the continuity light should be on.

The right pointset is mounted to a breaker half plate.
You will see that you can loosen the mounting screws on this breaker
half plate and this will allow you to move the right pointset. This will
adjust the timing without changing the points gap. When you rotated the
complete breaker plate for the left pointset to get the continuity light
to flicker out, thats what you did. You adjusted the timing on cylinders
1 and 4 without changing the gap on their pointset.
Unfortunately, the whole breaker plate being rotated moves BOTH sets of
points, so that is why you must set the left side first and that is why
the right side is mounted on its own independent half breaker plate.
SOoooooo.... Smile Loosen the breaker half plate on the right side and
rotate as needed to cause the continuity light to just flicker out.
Tighten the half plate back down when satisfied with the adjustment. Smile

Remove continuity light and HOPEFULLY, start bike.

Earl

 

[KEITH KRAUSE]

You can also do as Earl says without a light. Just use the ignition spark instead of the light.
I'd still time it with a gun though. More accurate in my opinion.

 

[rustybronco]

150,150,(55) and 150 compression? hope it was a typo.