One cylinder off on Dyna Timing help?

[jjwithers]

I got a /2 hack running again after a LONG slumber.
It has a R90 engine in it and came with a Dyna Ignition.
First start up seems fine, and synced the carbs OK.

Runs fairly smooth but have not ridden it.

I Got my timing light on it and I'm seeing double (sort of).

At idle and high (3500) rpm, I am seeing the timing mark(s) in the perfect locations, but also slightly higher in the timing hole.
This leads me to believe one of the sensor posts on the Dyna timing plate is slightly off.

How do I figure this out... or better question is how do I statically (bench) time and engine with a dyna ignition? I don't have a buzz box or anything like that. Just a multimeter and timing light. I'm thinking that I need to find the ignition post (cylinder side) that is dead on and adjust the other post to advance or retard slightly to lower the timing marks in the window.

If I had to guess, on the flywheel timing window, one revolution shows the timing marks about 1cm higher then the one that is dead on.

[Kurt in S.A.]

I don't remember for sure, but I believe that (when viewed from the front of the bike) the left pickup is the coil for the cylinder on your left (it's the rider's right cylinder but this is when viewed from the front of the bike) and the right pickup is the coil for the right cylinder. You can find the small magnetic dot on the donut attached to the advance unit. Watch as it moves around...when the dot approaches a coil...that will be the one that will fire.

When I've had to adjust the timing on my /7 setup, I just picked one side and made a small adjustment then checked what happened to the timing. It won't take long before you figure out which coil you have change in order to get your cylinder timing where you want it.

Further thinking...you can put a voltmeter with the positive lead attached to the power-in point on the left-hand ignition coil (not the Dyna pickup coil) and put the negative meter lead on ground. When the points are "closed", you should see 12v input to the ignition coils. When the points "open" or the Dyna sensor triggers, the voltage will go to 0v. Check where the timing mark is. So, if you know where the small dot is on the donut, you can figure out which coil to adjust. Make the best adjustments you can statically then start the bike and confirm dynamically.

Kurt in S.A.

[Seth]

I did similar (small adjustments while not running, then restart and check again) when I installed a Dyna on an R90S.
It was tedious, but I got the double image to just about disappear.

I found that a double image at idle would also be a symptom of a loose timing chain, which would get better at higher RPM.

[jjwithers]

Good suggestions. Thanks.
I forgot to mention that due to the R90 engine in a /2 frame, I have a dual green dyna coil, so there is no left/right coil.
And the engine is fully rebuilt so timing chain isn't an issue.