Advance

[steve carty]

Hi members,
I need a bit of advice, I have a 1979 ss special but my bike won't advance and just revs at the F mark? Pampco ignition, cam chain adjusted, valves adjusted, carbies seem to be in sync. The advanced weights are moving quite easy on rotation. I put new sparks in and can only get a timing light read on left pot? I have checked the stator and rotor with multimeter and are ok. I have a solid state regulator/ rectifier. Any ideas?

 

[DogBunny]

Timing light on only one side indicates that only that side is firing. Are both headers getting hot?

My only guess regarding your advance, is that maybe the advance weights are moving TOO easily? Like maybe that are immediately fully advancing the motor? I think that if you point your timing light at the advance weights that you will "freeze" them so that you can see where the weights are. See if they are in or out (advanced) while at idle.

 

[Jan_P]

Hi
My first thought ..First to check if the weight movement it is actually also moving the advance axle
10.45 in that video

Then inspect the other side I don't know Pamco but there are some kind of pickup
With wires ...Inspect Please post pictures or what type of pamco. Someone will most likely know
I assume it is running on both cylinders and running properly.

 

[XSLeo]

With the Pamco it uses a dual output coil that fires both plugs at the same time.
This makes one plug positive polarity, the other negative polarity . This means the spark on one plug jumps from the center electrode to the ground strap. The other jumps from the strap to the center.
A lot of timing lights work best positive polarity but not so well with negative polarity. On the clamp that goes around the plug wire there is an arrow that should point to the plug. Try it both pointing at the plug and away. You may find it reads differently.
Using the timing light to look at the advance weights to determine if they move or not is a good way to see that.
If they move out at idle you have to clip the loop of one spring the turn up the next run for a loop. Mark this spring with a Sharpie. Thus way if it's not enough you can tell which is which so you can trim the other spring.
If they don't move at all they are to tight. You might try stretching the springs.
Are the springs on the advance the stock spring or replacements? The springs Mike's sell are often a bit loose andneed the trimming.
If you replaced the springs try te old ones.
Leo

 

[steve carty]

Thanks for all the replies, I now have something to start with, is there a chance that maybe the dual coil could be faulty?

Cheers

 

[XSLeo]

On the 79 with points it has two single coils. One for the right side, one for the left. And the coils if faulty may cause timing issues because the spark will be weak and not trigger the timing light.
Pull the plug on one side, hook the plug wire to it, hold plug against the engine and crank the engine and watch the plug. If it has a good spark then that coil is ok. Now do the other side. If it has good spark then the coils are ok.
Leo

 

[steve carty]

Thanks for all the assistance guys, it turns out the coils were ok so I checked the atu and XS Leo was on the money. I set the timing light on the bob weights and the springs were too tight. I stretched them a little and away she went. Happy days. Thanks again