I got my Ducati with 3000+ miles on it. Nothing had been changed. The bike was barely ridden in the 5 years the owner had it. Even the oil in the bike, was the same oil from the 600 mile service. You could imagine my distress.
After thinking about it for a while longer, I realized that the rubber belts (Kevlar re-inforced belts hadnt come out yet) we're also five years old. Then I actually thought about what it would be like to have a belt break. Pistons.. slamming into valves. Sounds all sorts of expensive. I guess I should probrobly replace them quickly. Off to California Cycleworks for parts, YET again.
First off, you want to remove the sparkplugs. This is pretty simple. Pull off the wires to the spark-plugs (they will go "plunk!") and unscrew the sparkplugs. I was a little paranoid, so I gently pulled them out. Look at the color of the plugs while you have them out. Remember that white is bad (lean), black is bad too (rich) but the poo-brown color, is juuuust right. Also, its important to note that when your re-installing the sparkplugs make sure that you use some anti-size compound on the threads of the sparkplugs. Whenever steel and alumninum meet, there is always the chance that they can "mate" together. Especially in high-temperatures. (Which you will get on a air-cooled 2V motor. Remember you only need about 15 ft/lbs torque re-installing the sparkplugs. So dont go crazy.
Next, take off the belt covers from the left side. (You will need to move the oil-cooler down to finangle the lower belt cover off.) This will expose the belts, and cam-wheels in all their glory. Looks simple right? Guess what. It is!
Since you have both sparkplugs out, you will be able to rotate the engine via the back-wheel. So shift your bike into 5th gear (dont try to start it, you removed the sparkplugs, remember?). With it in fifth gear, you will be to spin the rear wheel forward, to move the engine forward. Look closely on the cam-wheels. You'll notice little marks on the wheels and the belt covers. Line up the marks like the image to the left. This serves as a reference point when putting on the new belts. This could be the difference between a successful belt change, and a catastrophe.
Now with the belt-covers off, the timing marks lined up, and the spark-plugs out, its time to get these old belts OFF. Simply loosen the belt tensioners you see in the picture to the right. (They are indicated with arrows, clic for a larger view). Dont take the bolts out, just enough for the tensioners to slide outwards, and release the tension on the belts. Now belts will be loose enough for you to pull them off. Start with the horizontal belt first . This is actually the easiest belt to get on and off. Carefully slide the belt off the teeth in the cam gear, then slide it off the teeth from the crankshaft. The vertical belt is a little trickier, but not nearly as bad as you'd expect.
For the vertical belt, you need to gently wiggle the belt off the upper cam-wheel, then move it off the teeth on the crankshaft. After the belt is off, the cam wheel will spring to the forward or backward, and the dots wont line up anymore! Dont worry about it. Otherwise you'll be like me, and spend 15 minutes trying to get the cam-wheel to stay lined up. When we put the new belts on, we will move the cam-wheel back into position while putting on the new belts.
IMPORTANT NOTE: Make SURE to check your tensioner and idler rollers. Use your fingers and actually rotate them. Feel for any resistance or "gritty" movement. These are exposed bearings and can go. If they do seize up, or drag, then the lifetime of your belts will be severely reduced. If they break, your not gonna be happy!
To install the new belts, start with the vertical cylinder first. Loop the belt around the crankshaft spline. Now, move the vertical cam-wheel back into position with the timing marks lined up. Like I said before, it will want to spring right or left, so your going to have to hold it while you put the vertical belt on it. Make sure the belts are properly routed through the idler and the tensioner pulleys. The belt will either fit on correctly or it wont. From the pictures it might look like there is some "grey area" that could allow you to be off a tooth or so. But in reality, it'll be all sorts of easy to see if you've bunged something up. The horizontal belt is the same process, only much easier. Since the cam-wheel doesnt have the tension on it, you dont have to worry about holding the wheel into place. To the left is a picture of the belts installed correctly. (But not tensioned).
Now that the belts are correctly installed, you need to tension them properly. There are tools you can buy from ducati to do this, but those cost money. Here is the simple way to do it. Take a 5mm allen key, and put it between the idler roller (the one that cannot be adjusted). With one hand holding the allen key in place between the idler wheel and the belt, use your other hand to push the tensioner against the belt, as tight as you can. Here's where you have to play twister with yourself to make it happen: While holding the tensioner in place, take your hand off the allen key (the tension on the belt will hold it in place), and tighten down the tensioner bolts. To check tension, push down on the belt (hard, but with one finger) and see if you can pass the 5mm allen key underneath the IDLER roller and the belt. You shouldnt have to force it, it should sweep underneath with a bit of resistance. 9 times out of 10, this method works well. The belts are tightened juuuust right, when a 5mm allen key will sweep, but a 6mm allen key can't. Just repeat for the vertical cylinder, and presto.. your belts are on and tightened.
Here we show both belts on, and properly tightened. With the sparkplugs out, make sure to rotate your rear wheel in 5th gear a couple times just to make sure that nothing is rubbing on the belts, and that nothing looks out of the ordinary. When your satisfied, put those spark plugs back in (remember to use the anti-seize compound!) and with the covers off, fire up the bike! Just watch the belts for a few minutes, make sure everything looks right. I took a short video of my 900SS running without the clutch-cover, or belt covers. Damn, that clutch is loud!