timing between 1/4 and 2/3 is way off

[petrolhead]

Hi fellows,
I have a ? 77 750 with a timing issue
With the points set i had to redrill the bolthole for the points-set because it was to far off to be able to set correctly.
When i switched to Dyna S i still had to make adjustmemts wich was hardly possible with these pick-ups.

What can be the reason for the differences ?
Everything;from the advancer to the the groundplate spacings should be 180degrees devided.
What can effect the 50% interval between both top ends ?

 

[unfocused]

77 GS750 w/ Dyna S

I had to adjust the timing on 2/3 pickup with my Dyna S. You don't need much movement to adjust these to get your timing right.
Set 1/4 first and then went after 2/3. 2/3 was off. Went back and checked 1/4, moved pickup on 2/3 and everything came around. My timing is set.

As for the reason for the difference, ??? However, it's a mechanical device from the 70's. Manufacturing wasn't as good back then LOL

 

[petrolhead]

Thanks for the reply Unfocused,
If it was a small adjustment i would not have bothered writing a post.
I guess i have to examine the governor assembly for accuracy and 180degree spacing.
I am surprised; it seems like a solid part with some slight clearance between the weights and the rotor.
No play or wear between rotor and stem, weight bushings etc.
Anyone else have experienced a governor assembly wich does not devide 180 degrees ?
Or is there still another option ?

 

[Grimly]

I recently discovered my timing on 2/3 had drifted a couple of degrees advanced. 1/4 were still bang-on.
Because it's a retro-fitted electronic system it normally takes no servicing input and for years I'd just assumed it was hunky-dory. Turned out not to be the case, as I found out.
The difference is immediately noticeable, much smoother overall. *
Not that it was rough before, but the change had happened gradually and hadn't actually reached the point where it was causing a problem.
Last time I checked it with a timing light was when I rebuilt the top end and repaired a burnt pickup wire from the crank sensors to the ignitor (it had fallen on to the exhaust pipe). I'm utterly sure it was bang-on then.
However, the current ignition system is a 40 year old Piranha ignitor with opto-electronic pickups, and it might be starting to show its age by now.
I have a cheapo China Dyna system sitting ready to go on at some point.

* I also found a couple of crusty connectors on the feeds to the coils and ignitor, which weren't helping things.