Last time I changed belts I used a weird method I saw. It worked but it was too complicated (I over think shit). Watched two recent videos that appear to show the correct way. Here's my question that they don't answer. Once I take the belts off, I can spin the three shafts 100 ways back and forth, and as long as I have the 3 marks on their spots, that's all I need for it to be in the correct time? Am I making a lick of sense?
That's been my thought as well. As long as when the belts go back on all the marks line up you should be good. When I've done it in the past it seems like one of the cam gears (usually the vertical one) has to have a bit of tension on it to get it at the right spot which can be a little awkward if you're doing it by yourself. Once the belts are on, I just use a 5mm hex wrench to check the tightness. Just don't loosen those three hex bolt at the end of the cams and you should be good. There are some good pics on this page showing the alignment of the marks: https://www.ducatimonster.org/threads/how-to-belt-change.138982/page-2
That's exactly how I saw it. It almost seems too simple to be correct. And I saw the 5 should pass but 6 shouldn't. Is it really this easy?
Ha! Yeah I was worried the first time I changed a set but it all worked out. I'm old school and my Ducs are all older 2Vs so I've always just used the 5mm wrench method to set tension. I think another common way to check it is with an audio frequency meter ($$$) or even a guitar tuner (I think they should be "tuned" to 110hz or basically "A") ... I've heard it works, but I've never tried it.
i've done the tension on new belts with the Gates app. from what i can tell, it works, engine hasn't blown up yet (4V). what i also do is before removing the belts is marking the old belts according to the gears, then transferring the marks to the new belts just to be sure...
That's exactly how I did my last change. Don't remember where I saw the video, but that's what they showed me. Then I saw a new video showing what I described above and it seemed too simple.
Belt tension apps are free...probably a good idea to use them vs trying a wrench fit/no fit. There's no way to determine how much force each person is applying to said wrench etc. Also yes, just line the marks back up - layshaft, cams and toss the belts back on. Easy peasy. People generally make too much of it.
Interestingly enough, I tossed this question over on the Ducati.ms forum and there is now a discussion that while the cam gears don't matter as long as they're lined up, the crank gear does matter...it needs to be at TDC on the compression stroke. There's an argument now as to whether that's correct. Or is it automatically at TDC when it's on the mark?
The crank doesn't know the difference between strokes, it only knows TDC, BDC, etc. It's the cams that determine if it's the compression stroke or not.
Because the camshafts spin at half the speed of the crank, the TDC mark on the layshaft/cases means TDC of the horizontal cylinder or one revolution off. But the horizontal piston is always at TDC if the layshaft mark is lined up. In the most basic terms, if the layshaft mark lines up at TDC AND the cams are in the correct position - that's it. There's nothing else to check.