Timing question....79GS750L

[ToddB3]

I read Earlfor's directions on timing and points gap for the GS750 and followed it to the "T" yet I have what may be a stupid question, when you align the F1 mark with the stationary mark,which mark do you use? My bikes f1 mark for example looks like this: ! F1-4 ! Do I use the left or right line or do I center it? Also when timing I dont have a continuity light so I used a multi-meter and rotated the timing plate all the way left to right and the voltage never changed much. I hate to sound so ignorant but this is the oldest tech bike I've ever worked on.

[SqDancerLynn1]

The timing mark should line up with the line on the left side of the F1 mark thats TDC

[Anonymous]

Connect your VOM (multimeter) across the points in the lowest OHMS range with the bike battery disconnected and the ignition off. Set the points to open and close right at the timing mark so that as you move the crank back and forth the needle swings just as the timing marks line up. Once you have this adjustment made for the 1-4 cylinders move the smaller plate to adjust the 2-3 cylinder timing.
GET A MANUAL!
Also stop at Pep Boys and get an inexpensive timing light so you can check the timing dynamically and check the advance to make sure it is advancing enough. A timig light can be used as a diagnostic tool to help detirmine if you have spark without removing the plugs.

Harrison

[Dink]

the reason the mark says "f1-4" is that it is the set that ignites both #1 &#4m as the ignition fires both plugs of the one coil each time, one coil fires 1 & 4 the other 2& 3.
Dink

[ToddB3]

Thanks for the advice, I know the process of the ignition but I didnt know which mark to align, I ordered a Haynes manual for the bike but I doubt it will be here for another week and I'm growing impatient. I think I've decided to start polishing the bike while I wait for more parts to come in and the manual.

Thanks again!

[earlfor]

You will see |F1 the mark (|) is the alignment mark. |F1 is for static timing of the 1 or 4 cylinder and is the left set of points. |F2 is for static timing the right set of points and applies to the 2 or 3 cylinder.

|F4 is the dynamic (32 deg's advance mark) for the left set of points and the 1 or 4 cylinders. |F3 is the dynamic (32 deg's advance mark) for the 2 or 3 cylinder and is the right set of points.

Advance timing may be set static if the centrifugal timing weights behind the breaker plate are in the extended position. Otherwise, a dynamic timing/stobe light must be used.

Earl

Thanks for the advice, I know the process of the ignition but I didnt know which mark to align, I ordered a Haynes manual for the bike but I doubt it will be here for another week and I'm growing impatient. I think I've decided to start polishing the bike while I wait for more parts to come in and the manual.

Thanks again!

[ToddB3]

Thanks for all the advice guys, my main question is which line do I align with the stationary mark, mine looks like this lf1-4l I'm assuming you align the stationary mark with the mark to the left of the F in F1? or is it the one right of the 4?

[Dink]

The one to the left, the one to the right is for the advance and you require a timing light to use it.
Dink

[earlfor]

Use the mark |F1
The mark on the left side of the F

|F1
^
^
^

Earl

Thanks for all the advice guys, my main question is which line do I align with the stationary mark, mine looks like this lf1-4l I'm assuming you align the stationary mark with the mark to the left of the F in F1? or is it the one right of the 4?

[ToddB3]

Earlfor,

I'm a dumbass, I re-read your previous post about f1 f2 f3 f4 and I missed the what you were trying to tell me, I consider myself somewhat mechanical but timing is something I've never really had to deal with. My other bikes have electronic ignitions with fixed rotors so the only time I've used the timing marks is to find TDC. This bike will be an education! I'm sticking to cleaning and polishing until my manual gets here and I'll go buy a timing light.

[earlfor]

I'll try again..........:-) :-)

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.

Earlfor,

I'm a dumbass, I re-read your previous post about f1 f2 f3 f4 and I missed the what you were trying to tell me, I consider myself somewhat mechanical but timing is something I've never really had to deal with. My other bikes have electronic ignitions with fixed rotors so the only time I've used the timing marks is to find TDC. This bike will be an education! I'm sticking to cleaning and polishing until my manual gets here and I'll go buy a timing light.

[ToddB3]

Earl,

Got my manual in yesterday and I fully understand the timing process, I appreciate you patience while trying to explain it to me. During the wait for the manual it did give me time to sand and paint the frame and polish the case covers. I'll post pictures when I'm done!

[earlfor]

:-)

E.

Earl,

Got my manual in yesterday and I fully understand the timing process, I appreciate you patience while trying to explain it to me. During the wait for the manual it did give me time to sand and paint the frame and polish the case covers. I'll post pictures when I'm done!