I've decided to have a crack at changing the belts on my 916Bip myself, i've had a look at various clips on Youtube and i have the haynes manual, can anyone recommend a decent cam locking tool please, and it may seem a silly question but will i need to lock one set of cams or both?...all the vids i've seen have the tool locking the vertical cylinder only, with that locked can i be sure that the Horizontals won't move? ...first time i've done a Desmoquattro motor, i did my old 750ss years ago and IIRC it was fairly straightforward.
When you have the bottom pulley lined up with the mark on the crankcase the horizontal cylinder is at TDC, all valves are closed and there’s no spring pressure on closing rocker arms. The vertical cylinder however is not at TDC and there’s spring pressure on the intake closers which will cause that cam pulley to move as soon as the belt is removed. Use a tool to lock the vertical cam pulleys and the intake ones can no longer move as soon as the belt is removed. It makes life easier for installing the new belt as you’re not having to hold the intake cam pulley in position whilst simultaneously trying to fit a belt over the pulleys. You shouldn’t need to have to use a holding tool on the horizontal ones as they’re not ‘on cam’ and thus there’s no spring pressure trying to rotate the closers. When you measure tension make sure the respective cylinder is at TDC of its compression stroke and there’ll be no tension exerted on the belt by closing rocker arm springs trying to force the camshaft and it’s associated pulley round. I hope that makes sense.
If you have a 3D printer you can print a tool. There are some on thingverse you can download. You only need to lock the vertical cams.
As mentioned, you only need to lock the vertical cams. The inlet cam is on the nose of the cam when in the timing position. The Desmoquattro is about the easiest Ducati engine to change belts on. No need to count teeth or mark belts with paint. Just make sure the marks on the pulleys are still correct when you've turned the engine over a few times. About the hardest part of the job is removing the centre part of the belt cover around the frame
seconded, also heard this from a guy doing a mates belts, he said things get much more tricky with the testretta engines as partly due to emissions, things are a lot tighter in terms of tolerance etc
Actually, you don't need to lock them. Just be aware that you need to hold in place due to it being on the 'spring' and trying to move. I've got one of those simple locking tools that sits between the cams, holding the offending cam stationary (only one actually tries to move) but I can't use it due to having degreed the cams which puts it marginally out of alignment on the tool, enough to make fitting the belt tricky so I find it easier just to battle with it. You could also mark the pulleys in a different spot where the valves aren't on the cams (before removing the old belts) and then use that as your reference - as long as it all lines up when in the correct position.
@yellowducmaniac Martin is correct but just to clarify if you’ve marked the pulleys AND the belts the marks on the belts will not line up again with the marks on the pulleys after turning the engine over - don’t panic if you see that, it’s normal as a complete revolution of the belt is not an exact multiple of the revolution of the cam pulleys.
Just a further quick question please...got the bike stripped down and ready for new belts, I bought a pair of Gates belts and they have directional arrows on them - see pic, might seem a silly question but which way should the arrows be facing when I fit them?...towards the front or rear of the bike?..no marking visible on old belts although they look OK TBF, still gonna change them. Thanks.
No need for pulley holding tools as has already been said. Also counting teeth, painting marks etc all totally unnecessary. You have 5 marks in total on the belt pulleys, 1 on the lower pulley which drives both belts and then one on each cam pulley. Get all the marks lined up and by all means take photos for later reference. Slacken off the belts and remove them. Simply put the new belts on making sure that the 5 individual marks line up as they did before the old belts were removed, tension up the belts and you're good to go. Keep it simple and it's very straight forwards to do. Done all my belts this way on 748, 916, 998 1098 for last 15 or more years with no problems at all.
As you look at the old belts and cam pulleys in your photo above the belts rotate anti clockwise as the engine turns over so you want those arrows to be facing to the left on the top runs of the belts.
Ok, thanks for the replies, I'm getting conflicting answers though - can someone definitively confirm which way the arrows should face when fitted, I know that when rotating the rear wheel in direction of forward travel the pulleys rotate anti clockwise so the arrows should point to the left on the rear cylinder top run when viewed as in my pics?...sorry if I'm confusing things but better to be safe than sorry etc.
As the overwhelming majority of people on here probably use Ducati genuine or Exact belts you are best to check with the manufacturer although many would say that they would expect the arrows to indicate direction of travel.
Thanks again, and for your patience...another question - looking at my Haynes manual it states that when all marks on the Pulleys are aligned they should correspond with a pointer and line visible through the sight glass on the left side of the motor, looking at mine there doesn't appear to be any line to line up with the pointer, only a dot which isn't lined up with the pointer when all the pulleys are aligned, am i missing something here ?...i really dont want to F@ck this up!
Can you see the dot and the pointer? AFAIR, the pointer/dot is an indication that the piston is at TDC. Got a picture?
Ignore the arrows - they're of no consequence. At the drive pullies the right side of each belt tooth will be loaded, and on the cam pullies the left side of the tooth will be loaded.
I found this guide really helpful when I did my 916: www.tassell.co.uk/belt_change Picture from guide showing pointer and dot not quite lined up:
The way I read the Haynes manual is that when the sight glass pointer/dot lines up it should correspond with the cam pulleys also all being lined up correctly- is this correct?...or have I read it wrong,?
