While assembling the rear of my 750ss ie I thought I would try and find what the correct chain tension should be. With bike supported and no rear shock absorber fitted I lifted the swinging arm until the sprockets were aligned in a straight line and then tensioned the chain until there was just some slack at it's tightest point. I replaced the shock absorber and measured the chain tension with the bike on a rear stand which was 35mm up/down mid point of swinging arm. I have a 45t rear sprocket fitted but not sure if this had an effect on the result. Does this mean that 25mm is way too tight? I appreciate the swinging arm may never reach the straight line position in normal use but should you plan for the worst case scenario?
You need to work out the swing arm angle at full suspension travel as that is the only way to work out where to check for maximum tension. What you have done is make a wild guess and try to extrapolate the answer from that. Should we accept Ducati just made it up or that perhaps they knew the answer to calculating maximum tension and worked from there.
If you had taken the trouble to read my post you will see that i have worked out the point where the swinging arm position gives the maximum chain tension. I have not made as you say a wild guess but with a tension of 25-30mm the chain will be too tight when the swinging arm is in a position to give maximum tension. Instead of speculating about wild guesses why not try the experiment yourself, you might learn something.
The workshop manual agrees with you, stating 38mm slack. That is also in line with my own experience with my 900ss that there needs to be mid 30’s mm slack to avoid overtension under real load (annual short discussion with my local friendly MOT mechanic “chain is a bit slack” “not when I am sitting on it it isn’t” “uh… ok.”). 25mm might be reasonable if the bike was loaded with rider weight when checked, but it then becomes a 2 man job. I would say - Ignore the sticker. Edit: I noticed that the workshop manual is describing a different way to measure slack (distance to swingarm on deflection) so disregard that comparison, but I stick with my comment about 25mm being too tight.
