Ducati Sporting Club UK > Model Specific - Discussion, Technical Problems and Help > Monsters > Cambelt replacement

[Jools]

I've just changed the belts on my ST. They cost about £32 apiece from John Hacketts who will post them out for next day delivery.

Fitting them is really easy. All you do is take the belt covers off, get the bike on a paddock stand so you can turn the back wheel by hand, whip the plugs out so that there is no compression and put the bike in gear. Then you just turn the back wheel by hand until the timing mark on the crank pulley lines up with the mark on the engine casing - the other timing marks on the camshaft pulleys should line up with their respective marks on the casings and the horizontal cylinder will then be at TDC. Then slacken both the bolts on the adjuster pulley and take the old belts off.

Feed the new belts on and the only mildly fiddly bit is fitting the vertical belt. It has a helper spring on the camshaft so that the pulley will want to flick up or down away from it's timing mark, so you need to make sure that you hold it in line with the mark while you put the belt on. Keep holding the marks in alignment while you roughly tension the belt and just nip the adjuster bolts up. Repeat for the horizontal belt which is easy because the timing marks stay put.

Now the new belts are on, start with the horizontal cylinder and squeeze the adjuster to take up the slack until a 5mm allen key will snick between the belt and the fixed idler pulley reasonably easily but a 6mm allen key will be a struggle, then torque both the adjuster bolts on that adjuster to 25nm (I think from memory) you might have to repeat this process a couple of times until you are happy that the allen key test is repeatable once everything is torqued down.

Once you've done the horizontal cylinder, turn the engine over with the back wheel again through 90 degrees so that the vertical pot is now at TDC and repeat the adjustment for the vertical belt - it's a good idea to leave a little more slack in the vertical belt because the back pot runs hotter and you can allow for a little more expansion so I make sure a 6mm allen key will snick through and a 7mm wont - it's better to run the belts a tad slack than too tight.

Torque it all up then turn the engine over a few times to make sure that nothing is fouling and pop the covers back on.

It's easier to do than describe and there's a good video of it here http://www.youtube.com/watch?v=9vzPZ84ZRjU

[NBs996]

It's easier than that on the 620 Jools, no need to mess around with timing marks and tdc unless you think it's all got misaligned somehow.

near the camshaft sprockets there's a M5(?) threaded hole which you wind a bolt through to lock down onto the cam sprocket. Then just slacken the adjuster and slide the belts off.

New belts on, remove M5 bolts, tension pulley, fit covers, job done. Half hour job.

(edit - assembly sequence, how silly of me!)

[nelly]

Nick, remove the M5 bolt before you tension...... it's locking the pulley so you are effectively only checking tension on one side of the belt, not the assembly.

[Jools]

Originally Posted by NBs996

It's easier than that on the 620 Jools, no need to mess around with timing marks and tdc unless you think it's all got misaligned somehow.

near the camshaft sprockets there's a M5(?) threaded hole which you wind a bolt through to lock down onto the cam sprocket. Then just slacken the adjuster and slide the belts off.

New belts on, tension pulley, remove bolts, fit covers, job done. Half hour job.

Blimey...it was easy enough on the old ones to start with...never mind all this simplicity...where's the fun in that

[sarasark]

I have an S4R 996. I,ll bet its not that simple on mine.They need doing though as I wouldnt like to see the mess if they broke.I have a 900 2 valve as well so I think I,ll do that one first to break me in slowly.

[skidlids]

Originally Posted by sarasark

I have an S4R 996. I,ll bet its not that simple on mine.They need doing though as I wouldnt like to see the mess if they broke.I have a 900 2 valve as well so I think I,ll do that one first to break me in slowly.

For the S4R it may be worth you investing in one of the tools that hold the cams in line

http://cgi.ebay.com/ebaymotors/Ducat...Q5fAccessories

[Shazaam!]

Just as a reminder: one of the common causes of belt failures is a tensioner pulley bearing failure. These bearings should be inspected at every belt change.

[ducatiparts.110mb]

Asking about the risk is only half of the issue. If you are asking about the risk, as in probability, then its quite low.

The consequences,on the other hand, are off the scale.

The result is that for your age of bike, then you should change them NOW.

I have an S4R 996. I,ll bet its not that simple on mine.They need doing though as I wouldnt like to see the mess if they broke.I have a 900 2 valve as well so I think I,ll do that one first to break me in slowly.

The 4 valvers are not really any more difficult than the 2V bikes. You can make yourself one of those tools with a bit of MDF and some old bits of belt tacked on to it.
Mark