Timing a 1980 550 LTD

So I realized that the timing on my 550 is advanced too far, and is igniting at an inappropriate moment, backfiring and setting fire inside of my airbox, this is bad.

The bike runs, spudders, but runs. I have no idea how to time this thing it is much different than the points i was dealing with on my 77 650-C, anyone with advice on this matter? I dont have the means to get a hold of a manual at the moment, so pictures if anyone has them, mostly advice, is very much appreciated!

Hey, Man!

Don't forget I've got a running 550 over here that we can look at for a reference.

You can retard the timing by loosening the backer plates and rotating the whole backer clockwise similar to how you would on a 650 even though there's no points there. You should have some marks though, and there's an e-book floating around here for that somewhere, I think.

You also might double check to see that your plug wires are not crossed anywhere.

I think you might want to check the valves also, they may be tight

There isn't really any way to adjust the timing. The timing plate is not slotted for adjustment. It's usually close enough that the timing plate won't make much difference.

However, there could be a problem with the advancer mechanism. Take it apart and clean it. Check the springs. Lightly lube it.

Make sure to note how it comes apart. It can go back together either of two ways. Only one way is correct. If the rotor is installed 180 degrees out, the bike will only backfire and not run.