Topic: CB550 Pamco ignition cannot reach advance marks at 3500RPM

[akabek]

I have a 1975 CB550F that I installed the Pamco Ultimate ignition system on.  I set the timing at idle to the "F" mark but when I throttle up to 3.5K RPM I do not reach the advance marks.  During the installation I did not find a pin on my advancer mechanism which would need to be removed.  I can twist the rotor freely and it will return to the initial position.  When I twist the rotor the advance mechanism expands to the stops on both sides.  Did I do something incorrectly?

Below are couple of pics showing how I installed the rotor to the advanced mechanism.  The last pic shows the rotor twisted and the advance mechanism hitting the stops

[AJK]

Just a couple of things to check. When you tighten your little nut on the end of the ignition shaft, the whole rotor must be able to rotate freely and not bind against the flat face of the washer-bolt that the little nut holds in place.

If you don't have that pin to remove, then you are probably nearly there.

Have a read through these threads and see if it helps.


http://forums.sohc4.net/index.php?topic=113480.0;all

http://forums.sohc4.net/index.php?topic=122946.0

http://forums.sohc4.net/index.php?topic=137528.0

[akabek]

Just a couple of things to check. When you tighten your little nut on the end of the ignition shaft, the whole rotor must be able to rotate freely and not bind against the flat face of the washer-bolt that the little nut holds in place.

If you don't have that pin to remove, then you are probably nearly there.

Have a read through these threads and see if it helps.


http://forums.sohc4.net/index.php?topic=113480.0;all

http://forums.sohc4.net/index.php?topic=122946.0

http://forums.sohc4.net/index.php?topic=137528.0

I found the first two threads last night but not the last one.  I sounds like my springs are the problem.    Will buying new springs fix the problem or am I better off cutting half a ring off the spring and reshape it?

[pamcopete]

Spring tension is very important. If the springs are too loose, then some of the advance will be used up at idle leaving less for full advance. If the springs are too tight, then full advance will occur at a higher RPM. So, loose or tight springs will result in not achieving full advance at 2500 to 3000 RPM. You will either not achieve full advance, or it will occur at a much higher RPM, like 4,000 to 5,000.

You have to have an accurate tach as well. Typically, the tach on the bike is not accurate at idle speeds.

The coils produce a positive voltage on one of the plug wires and a negative voltage on the other. The timing light works best with the negative wire, but there is no easy way to determine which wire that is, so just try using the opposite wire in each pair of wires.

Take another look at the shaft of the advancer for that little pin. It must be removed and it is more common on the CB550 that the CB750.

[akabek]

Take another look at the shaft of the advancer for that little pin. It must be removed and it is more common on the CB550 that the CB750.

I will take another look for the pin.  When I bought my bike it had the Dyna S ignition so it is possible the pin was there prior to the Dyna installation.  I can twist the rotor freely where the advance mechanism goes right to the stops so I doubt it is a pin issue.

[AJK]

If the rotor is working correctly in that it is advancing as it should from the 'F' to || marks, but you are continuing to experience slight jumping around/jitter at 'F' at idle, then take out your springs, cut the half turn off the end and reshape the end of the spring to make the hook. This will slighty increase spring tension and will make no noticable difference to maximum advance RPM's, but will make significant difference to the idle and low end tractability.
  The pamco is a great system. Once you have a few of the nuances sorted out you will be very happy with it. Your bike will run great, start easy and give good mileage. Just work through those threads, make sure nothing binds and do your springs. If you do all the above, you will have rock solid timing at 'F' with no jump around, this gives you a nice idle & a smooth transition to || as you increase the bikes revs.
 You just need to keep in mind that all these ignition parts work as a whole, so be methodical and get to understand the system of parts. Things like play in the rotor to advancer coupling that i mentioned in those threads are part of that makeup, but once you sort them out, it will run great & then you can completely forget about it.

I have found that my tacho reads about 15% higher, tested against a digital rpm meter. Just bring up your tacho to ~ 4000rpms and time to the || marks, and let it sit where it will at idle, which will be pretty much bang steady on 'F' if you do the above.

[akabek]

My issue is after I set the low idle timing I cannot advance the timing mark to the two advance markers when running at 3500RPM.  Based on the threads I have read it sounds like my tach  is not registering correctly.  Something else I need to consider is my bike is not stock.  I am running with a big bore, CR26 carbs, velocity stacks with ITG sock filters, 4-1 with an open cone engineering muffler.

I have an analog tach and a digital Acewell speedo.  With the Dyna ignition I could not get the Acewell tach to work properly.  The tach is still jumping around with the Pamco ignition but maybe I will move the RPM lead from the spark plug wire back to the coil to see if I can get a steady reading.

Worst case I will look for another tach to use for ignition timing.  Tonight I will time the ignition to the advance marks and see where the timing marks lands at idle.  I will see if I can drop the idle down to line up the timing mark to the F mark.  Maybe I will need to do the spring mod as well.

[AJK]

My issue is after I set the low idle timing I cannot advance the timing mark to the two advance markers when running at 3500RPM.  Based on the threads I have read it sounds like my tach  is not registering correctly.  Something else I need to consider is my bike is not stock.  I am running with a big bore, CR26 carbs, velocity stacks with ITG sock filters, 4-1 with an open cone engineering muffler.

I have an analog tach and a digital Acewell speedo.  With the Dyna ignition I could not get the Acewell tach to work properly.  The tach is still jumping around with the Pamco ignition but maybe I will move the RPM lead from the spark plug wire back to the coil to see if I can get a steady reading.

Worst case I will look for another tach to use for ignition timing.  Tonight I will time the ignition to the advance marks and see where the timing marks lands at idle.  I will see if I can drop the idle down to line up the timing mark to the F mark.  Maybe I will need to do the spring mod as well.

If thats the case, then you are not getting full advancer travel. This is odd because you say there is no pin. Either way, get a protractor and check that you are getting full swing. You should be getting about 25 degrees swing in your advancer. Meaning that you statically time it at 'F' which is 10 degrees advance, and with the 25 deg you just checked, lands you at 35 degrees at the ||. These are settings for the 750 advancer, but should be somewhat similar to yours. Its real important to have this sorted out, but strange that you have reported this problem with no pin present.

Dont worry about all the non-stock stuff for now. Just get the advancer working as it should, then you can tweak the advancer start and stop positions with differing spring tension to suit your mod optimisations. This is a separate project, so leave it for now.

If you can't get decent tach readings, then give the bike some revs that seem uncomforable to hold at idle, without ringing its neck out. That should be a seat of the pants ballpark (pardon the pun).

If you have steady firing at 'F' or around it, then dont worry about the spring mod. If you having timing jitter/jump-around, then consider the spring mod and items from the other threads.

[akabek]

If thats the case, then you are not getting full advancer travel. This is odd because you say there is no pin. Either way, get a protractor and check that you are getting full swing. You should be getting about 25 degrees swing in your advancer. Meaning that you statically time it at 'F' which is 10 degrees advance, and with the 25 deg you just checked, lands you at 35 degrees at the ||. These are settings for the 750 advancer, but should be somewhat similar to yours. Its real important to have this sorted out, but strange that you have reported this problem with no pin present.

I will double check to see if there is a pin.  In an previous thread someone did not remove the pin during their installation and their ignition was permanently advanced.  If you look at my pictures my advance mechanism has full range from point 0 to twisting the rotor and the mechanism touching the end stops.  Based on the full range in movement there can't be a pin blocking movement.  Something else to consider is that I have new carbs and I have been workong my jetting.  The carbs came with 55 pilots and I currently using 70s.  This may be effecting my idle as well.  My gut feeling is that the advance mechanism is working fine.  I need to sort out my idle...possible smaller pilot jets and get an accurate tach.

[AJK]

If thats the case, then you are not getting full advancer travel. This is odd because you say there is no pin. Either way, get a protractor and check that you are getting full swing. You should be getting about 25 degrees swing in your advancer. Meaning that you statically time it at 'F' which is 10 degrees advance, and with the 25 deg you just checked, lands you at 35 degrees at the ||. These are settings for the 750 advancer, but should be somewhat similar to yours. Its real important to have this sorted out, but strange that you have reported this problem with no pin present.

I will double check to see if there is a pin.  In an previous thread someone did not remove the pin during their installation and their ignition was permanently advanced.  If you look at my pictures my advance mechanism has full range from point 0 to twisting the rotor and the mechanism touching the end stops.  Based on the full range in movement there can't be a pin blocking movement.  Something else to consider is that I have new carbs and I have been workong my jetting.  The carbs came with 55 pilots and I currently using 70s.  This may be effecting my idle as well.  My gut feeling is that the advance mechanism is working fine.  I need to sort out my idle...possible smaller pilot jets and get an accurate tach.

Ok, then it looks like you are probably getting full travel based on that.

If the pin were in place, then what happens is that it prevents the rotor from advancing all the way. PamcoPete recommends to file it off it its present. I left mine on but modified my rotor once i figured out what was going on. From what your saying, you have nothing to worry about and its working full swing.

If you have a timing light, all the above is dead easy to check.

[akabek]

Tonight I had some success.  I dropped my pilot jet from 70s to 60s and I was able to get the bike to idle lower and I could reach the advance timing markers.  I need to get my jetting sorted and then I will be able to do a better job on timing and syncing the carbs.  Thanks for the assistance.