'78 CB550 -correct firing position at full advance?

The previous owner of my CB550 installed a full Dyna 2000 ignition on it. The one that not only replaces the points but also get's rid of the advance mechanism and controls ignition electronically. It also has a few spark advance curve settings. Maybe over kill for this little bike but hey, it's already there.

I've got it on the advance curve setting it recommends, 25 degrees of span and full advance at 3,500 RPM, and it seems to run just fine. The manual for this thing is written in a kind of general way as it will work on several different bikes and recommends about a 40 degree BTDC firing position at full advance. My question is is this the correct setting for a 550?

'About 40 degrees' is a bit of a general term and a couple of degrees one way or the other probably won't hurt anything but I'd like to get it as close to right as possible.

Thanks for any input.

what are you using for timing marks to set it ? you would need to use a timing strobe light and check it with a timing light at an rpm above the full advance in the box, above 3500

The crank trigger has timing marks on it. It's only marked between 30 and 40 degrees. The way the thing works is you set the total, full advance timing that you want. Then based on the advance curve setting selected it sets up the idle firing position and then advances spark as RPM increases. It's working, it runs good. I'm just curious if there's an exact position the 550 is supposed to run at full advance.

I've got a timing light. At full advance it's right at about 40 degrees. Maybe 41 or 42 but pretty damn close.

well each engine is different and also load temp and fuel grade makes a difference as well as many other factors
going to far advanced runs into the danger of creating too much heat and even destruction
if it can handle 40 degrees it may be the best setting, a dyno would be best way to verify
just keep your ear tuned for any engine knock when under a load this would indicate the bneed to back off the timing a skosh