Changing the cam belts on your 2 valve Ducati is a simple procedure and one that should be done at the required intervals. Belts are inexpensive compared to replacing the valve train: replace the belts as required in the maintenance manual.
Disassembly is the first step in replacing the cam belts. The photographs show the sequence on a M900 motor on a bench. Disassemble enough to allow access to the cam belt covers. Remove the cam belt covers as follows:
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Ducati - D.I.Y - simplified
When the belt tension is complete, reassemble the covers, oil pressure sensor, and sensor lead. Remove the engine rotating tool. Install the spark plugs and leads. Inspect the cover plate o-ring looking for nicks, cracks, or cuts. Replace the o-ring if defects are found. Reinstall the cover plate and snug up the bolts. Complete installing interferences removed. The belt change out is complete.
A properly tensioned belt will display 110 on the meter. The tolerance is plus/minus 5 Hz. Here is an acceptable reading on the meter.
Frequency too low:belt not tight enough.
Outside the meter’s range (too tight)
Belt tensioned correctly)
With the tension on the belts released, remove the belts. Begin with the horizontal cylinder and slide/work/wiggle the belt off the cam gear first, then the crank gear. After the belt is removed from the horizontal cylinder, remove the belt from the vertical cylinder.
Inspect the tensioning roller and the intermediate rollers for wear. Use your fingers and spin the rollers. Check for play and or smoothness in the rolling motion. If there is more than a nominal amount of play or the rolling action isn't smooth, it is time to replace. Clean the rollers and areas around the gears.
Slide the new belt onto the crank gear. Making sure the timing marks stay aligned, slide the belt onto the cam gear for the vertical cylinder. It is a snug fit and may take some patience to get the belt on. In this picture the tensioning rollers have been removed for cleaning and aiding in installation of new belts. DO NOT use a screwdriver or other sharp tool to coax the belt onto the gear.
Slide the belt so it is fully seated on the cam and crank gears.
Reinstall tensioning roller if it was removed.
When looking at the engine from the left side, the engine rotation is counter clockwise. Verify the motorcycle is in neutral and using the engine turning tool, rotate the engine counterclockwise until all three timing marks line up. The horizontal cylinder will be at Top Dead Center when the timing marks align. The timing marks are on the cam belt gears and on the engine case.
REMOVE THE SPARK PLUGS
Remove the cover plate from the left side of the engine and install the engine turning tool. Gently tighten the engine turning tool securing bolt.
Loosen the bolts securing the cam belt covers to the engine.
When both belts are tensioned correctly, use the engine rotating tool to rotate the engine through several revolutions. Align the timing marks and check belt tension again.
If the reading is outside the meter’s range or too low as pictured above; gently loosen the retaining bolt and apply more/less tension to the belt and check again.
Properly tensioned belts give the best assurance of long life and performance for your engine. It is easy to over tighten the belts: The best way to know for certain the tension is correct is to use the cam belt tensioning tool. It is an electronic tool that measures the frequency emitted by a belt under tension (much like a guitar string). Start with the vertical cylinder. Apply tension on the belt using the tensioning pulley and tighten one of the tensioning pulley retaining bolts. Place the probe end of the meter near the flat (outside) side of the belt. The correct location is about midway between the intermediate roller and the cam gear.
Using the thumb or forefinger "pluck" or "strum" the belt: the belt will vibrate and the meter will briefly display the reading. The different types of indications the meter will give are pictured below:
Install the belt on the horizontal cylinder.
Both belts installed and awaiting tensioning.
Once the bearings, gears and surrounding areas have been cleaned and inspected, it is time to install new (or old if they have few miles) belts.
Verify the gears are still in alignment with the timing marks on the engine. Cam gears can move during the belt removal process.
Loosen the nuts securing the cam belt tensioning rollers to release the tension on the belts.
Remove the bolts securing the cam belt covers to reveal the cam belts.
Remove the electrical lead from the oil pressure sensor. Clean the area around the oil pressure sensor. Remove the oil pressure sensor using a 22mm socket or a crescent wrench.