Update Timing Chain? issues left cylinder Tonti Big Block

[80CX100]

I've gradually sorted through the electrical issues on my '80 CX100, and am finally at the stage of doing a final tune/set up,,, this engine has the dual point system.

When I try to set the static timing, I am unable to retard the left cylinder far enough. I really like the idea of the reliability of points and keeping the original stock Marelli points(which didn't look bad (24K miles), but thinking it was a possible "wear issue", I threw in a new set of "Chinese" replacement points I had on hand,,It didn't help,,.

I was up all night trying various solutions,,, I've read through the many posts describing Greg Bender's "point's plate modifications"(filing the left point plate mounting holes,,,done) and also the many posts describing "cheating the gap",,,done,,, all to no avail.

I've gone as far as,,, filing all mounting holes and obstructions in the left point mounting plate&base plate, as far as possible,,, cheating the gap as much as .02 point gap for the right cylinder and .012 point gap for left,,, turning the distributer all the way clockwise, retarding the right cylinder points opening as much as 5 flywheel teeth after the static timing line,,,, but after all that my left cylinder points still are still about 12-13 flywheel teeth too advanced,,,wtf!.

I think it's at this point that Dave Richardson in Guzziology recommends being a good time to install the Dyna 111 electronic ignition,,,but I am very reluctant to go down this road,,, I've read most of the good/bad pros/cons posts concerning points vs Dyna,,, speaking from personal experience,,, the only time in my life that a bike went completely dead and I was unable to fix it and get it going,, was when the CDI black box on my old '72 H2 Kawi triple died, so I am a little leary of magical black boxes, although I'm sure they've improved over 40 yrs.

Is there something that I'm overlooking(screwed up?) with my points installation/modifications? I would really like to stay with the reliable dual point system,,, but if I can't get it set up properly and have to make the transition to an electronic ignition,, what is the best/most reliable system out there?

In 2015 terms,, have the Dyna issues from the past been sorted?

I've read up on the C5 Ignitions, (comes with it's own coils),,, but included in my work on the bike,,, I worked very hard to fit in a pair of Bosch Blue coils under the tank,, so I'm hoping that if I'm reluctantly forced to go down the electronic igniton road,,,that whatever ignition system I go with,, will be compatible with those coils.

Any and all suggestions and comments are appreciated.

tks in advance
Kelly

[rodekyll]

Within reason you can change the points gaps to make the angle.  Point gap is not as critical on a guzzi as a chevvy.

[Vasco DG]

Yup, just juggle the gap/dwell. Time it right, make sure it doesn't break down at higher rpm and then just re-adjust by re-gapping in future. Make sure the points heels are lubricated.

Pete

[80CX100]

Yup, just juggle the gap/dwell. Time it right, make sure it doesn't break down at higher rpm and then just re-adjust by re-gapping in future. Make sure the points heels are lubricated.

Pete

Pete,    I appreciate your advice,,, the point cam appears good(was lubed well),,, I've read the recommendation, of juggling the point gap to .018 for the right side and .013 for the left,, I've gone past that to .02 right/.012 left,,, if I go much more than that,,, it appears to me that the right points would never make contact(dwell), and the left wouldn't open far enough(possibility of arcing?),,, it just seems to me that,,, I'm not even close,,, I've got almost a 20 tooth difference on the flywheel to make up,,,,

How would I determine if the point cam was neglected in the past and possibly toast now?

Changing the points was a pita,,, but I'm wondering if the Marelli's might be worth trying again, with the plate mods and gap cheating,,, are the chinese points known to be more problematic?


"Within reason you can change the points gaps to make the angle.  Point gap is not as critical on a guzzi as a chevvy. ,,,Rodekyll"

    Rodekyll, I agree with you, and understand how understressed/overdesigned the dual point system is,,, but see my comments above,,, I haven't been able to make up that much difference, and I still have a long way to go.

Tks Kelly