It is recommended that you change the cam/timing belts on the Ducati 748/916/996 every 2 years or 12,000 miles. Some will say 6,000 miles just to be safe. The 2-year interval is important, as the belts can go slack just from sitting. While you would then only have to adjust the belts in that case, belts aren’t expensive compared to the amount of work required to change them, so it seems worth it to just use new belts.
After doing much research on the subject, I decided to tackle this bit of maintenance myself. I followed the procedure outlined here and here (same writeup, different sites–in case one disappears) up to step 19. For setting the tension, I used the acoustic tuning method described here.
Give yourself time. Make sure the bike is in a place where you can leave it in pieces overnight if you encounter any unexpected issues. Here is a summary of my experience, with a few additional pieces of info:
- Right electrical bundle: 5mm allen
- Unclip rectifier
- Battery clip: 8mm
- Battery box bolts: (2) 8mm
- Uncork rubber left bundle
Getting to the Motor
- Don’t fill the gas tank. You need to completely remove it from the bike, and it will be much easier with as little fuel as possible.
- Removing the seat will give you some wiggle room, but know that the hinge is delicate. I left mine on.
- Tank bolt (under seat): 5mm allen
- I’ve read the in/out fuel tubes are interchangeable. They stay in place pretty well, either way, and will line up when reinstalling the tank. If you want to be sure that all the tubes will return to their original partner, label them with masking tape.
- Airbox: (6) 6mm allen (2 rubber in front, four regular), (4) clips
- Front fairing: (2) 8mm
- Spark plugs: (2) 5/8″ – OEM is Champion RA59GC. There is no NGK equivalent. Turning the front wheel helps to access the horizontal cylinder plug. It can be hard to get at due to clearance issues. I had to install my socket and extension on the plug first, then attach my socket wrench to the extension.
- Belt tensioners: 22mm (box wrench helps) for adjuster, 12mm for locking flange nut (to prevent the adjuster from moving). I don’t believe the lock nuts are special, you can probably grab any 6mm (M8) locking flange nut from a fasteners retailer. That said, the Ducati part number is 74940081A and an equivalent Honda part number is 90309-428-731.
- After the belts have been removed, the right cam wheel on the vertical cylinder will be twisted (unless you used the handy cam wheel holding tool). It is difficult to hold in place while installing the belts. This is what I did: Line up the bottom marks (cam wheel, case, and belt) line up the right marks, then twist the right cam and belt as one until you are able to hook the belt onto the left cam wheel with the marks lined up. I read about another (possibly simpler method) here: “Turn the engine so the crank pulley moves in the CCW direction about 5 teeth. I then rotate both head cam pulleys the same amount and then put the belts on. I then rotate the engine 5 teeth to make sure all the dots line up.” Make sure the cam wheels don’t make any full revolutions.
- The horizontal cylinder is at Top Dead Center (TDC) of the compression stroke when the marks on the cam wheels are lined up with the marks on the engine case (the belt marks may not be aligned if the motor has been turned). In any event, the TDC and flywheel window stuff can be ignored; the effect on belt tension is negligible.
- When tensioning a belt, always end on a tension stroke. In other words, if your tension is too tight, loosen it a bit more than you need to, then tighten back up (like a guitar string). This isn’t crucial, as you’ll be turning the engine over a few times to test that the tension remains consistently in spec, but it’s a good practice.
- Belt tension should be within 5 Hz of 110 Hz. Err on the loose side.
- To measure the frequency of the belts, I used a Windows XP laptop, free software, a preamp, and a mic. A lot of things will work (certain guitar tuners, possibly an iPhone), you just want to be sure you’re getting an accurate reading. My equipment returned strong and consistent frequency measurements when I plucked the belt.
- Rotate the motor around and test again. Tension should remain consistent.