Dyna S & Timing question

[dardoonk]

Okay gurus.. I need some advice on setting the timing on my GS750B. I have new Dyna coils (green), wires, & Dyna S ingition. Per their website instructions, I'll have no problem following them, so my question is more about where to set the timing rather than how to set it.

Starting with the 1-4 pickup, the Dyna website says to use 2500 rpm in order to set them at full advance, now here's where I have a question:

1] According to my service manual, that should be 37 degrees BTDC. In other words, it is a total advance of 20 degrees because my timing at idle should work out to be 17 degrees BTDC. Do I have this correct??

2] Is this the best place to set the timing, or will I benefit by setting it a little further advanced?? If so, where should I put it??

Thanks.
Kurt

[earlfor]

Looking through the timing window in the breaker plate, you will see the advance counterweights. The timing marks are stamped to be viewed through the timing window. You will see two sets of marks that are spaced 180 deg apart. The first set will appear as
| T ........|F1 ....|F4. (I used the periods between because the bulletin board will not let me use spaces and drops them from my post)

The mark before T is top dead center. The mark before F1 is for timing at idle rpm before the advance mechanism has become active and engine rpm should be between 1k and 1300 rpm when setting advance at the |F1. The mark before F4 is the full advance mark which is normally only used with a strobe timing light and the engine running 3500 rpm or so.

180 deg away, you will see |F2 |F3. The mark F2 is the idle timing mark for the #2 and #3 cylinders.
The mark F3 is the full advance mark.

There is no reason to change the timing from stock with the addition of a Dyna S system. Besides that, full stock advance is about all the engine can use without the timing causing pre ignition. Pre ignition will burn a hole in a piston in nothing flat. Not good.

On every GS model I have owned and thats most of them :-), full advance is 32 deg BTDC.

Earl

[SPARKSS]

Okay gurus.. I need some advice on setting the timing on my GS750B. I have new Dyna coils (green), wires, & Dyna S ingition. Per their website instructions, I'll have no problem following them, so my question is more about where to set the timing rather than how to set it.

Starting with the 1-4 pickup, the Dyna website says to use 2500 rpm in order to set them at full advance, now here's where I have a question:

1] According to my service manual, that should be 37 degrees BTDC. In other words, it is a total advance of 20 degrees because my timing at idle should work out to be 17 degrees BTDC. Do I have this correct??

2] Is this the best place to set the timing, or will I benefit by setting it a little further advanced?? If so, where should I put it??

Thanks.
Kurt

Hi there Kurt. Earl has good advice. BTW your base timing would be 17 degrees, your centrifugal advance 20 degrees and your TOTAL advance 37 degrees (in your description). If you have stock compression and, like most of us run typical pump gasoline, then 32 degrees would be a safe figure if it doesn't rise to that too fast (this is your ignition curve). Overadvancing timing (with nothing else changed) will cause pre-ignition as mentioned.....and will be more prevalent as the engine warms up and/or on a hot day/hot ride etc. I find it nearly impossible to hear pre-ignition happening on a bike engine with the ambient noise level (and at the point where you HEAR it, it's gotten quite bad!).

[AOD]

As mentioned above, you can use the timing window and light to adjust the base timing by making gross adjustments with the three large screws on the outside of the timing plate.

To make fine adjustments for cylinders 1-4, 2-3 you need to use the small allen wrench provided and adjust the actual pickup on the timing plate.

~Adam

[dardoonk]

Okay, I know what understand what I need to do now. I was just thrown off a bit because the Dyna website says to FIRST set the ingition timing to 37BTDC with the engine running over 2500rpm (full advance). I was expecting to set the timing at idle to 17BTDC before checking to see where I am at when fully advanced. Either way, it should work out as long as my ingition advance is functioning correctly. Right?

[earlfor]

Set the ignition advance to the |F1 at 1200 rpm for the 1,4 cylinders (left set on the breaker plate) Rotate the breaker plate if need be to do this. Then put the timing light on the 2,3 side and check that it is on the |F2. If it is not, then you will need to adjust the right side trigger on the breaker plate. Once you have both sides on the marks, the centrifugal advance weights will open as rpm is increased. They will be wide open (max advance at aproximately 33-3500 rpm. (it will vary somewhat due to spring age, etc)
With the advance wide open, if the springs are within spec's, you should automatically have full advance showing on the timing light on the |F4 for the 1,4 side and the |F3 for the 2,3 side. If you do not, then you rotate the breaker plate to make the max advance align with the |F4 and |F3. The idle mark setting is not critical, but the advance mark setting is.

For what its worth, I have bought and installed 10 or so Dyna S systems and I have not received a one that had the modules out of alignment on the breaker plate. I have never needed to change the factory setting. They have all been dead on, 180 deg apart, perfect.

As I said, standard advance is 32 deg on GS models and that amount of advance does not come in until about 33-3500 rpm. You do not want 37 deg at 2500 rpm. On my 1150, I ran 34 degrees, but I was also running a Dyna 2000 system with programmable ignition curves. To run 34 degrees without preignition, I found I needed to delay the curve and retain 32 deg until 4500 rpm was reached, and at that point, the system went to the full 34.

Also, if you do find you need to move the crank triggers/modules, be sure to retain the correct gap while changing the timing alignment. The system will not function reliably (if at all) if you do not.

Earl

Okay, I know what understand what I need to do now. I was just thrown off a bit because the Dyna website says to FIRST set the ingition timing to 37BTDC with the engine running over 2500rpm (full advance). I was expecting to set the timing at idle to 17BTDC before checking to see where I am at when fully advanced. Either way, it should work out as long as my ingition advance is functioning correctly. Right?