Monday, October 18, 2010

Desmoquattro (4 valve) belts and valves service

This is a short description of how to change the timing belts and how to check the valve clearances. Particularly I will share tips and tricks you need to know.
First, get yourself the following (must have IMHO:

  • 1) guitar tuning or audio analyzer software for your laptop. You will need it to check the tension of the new belts
  • 2) paint marker
  • 3) torque wrench
  • 4) mechanic gloves, several of the tasks require handling or working around objects with sharp edges
  • 5) engine rotating tool
  • 6) belt timing lock for the vertical cylinder. Get the original or, even better, get the after market part for around $20. I used it, it works beautifully.
  • 7) watch the three videos on the topic by California Cycle Work http://www.youtube.com/user/cacycleworksdotcom this will prepare you for the work ahead

Replace belts
I am going to skip the basic and focus on what you need to know. Start by removing the fuel tank and pay attention to the fast disconnect lines and where they go. Once you have the tank out of the way, remove the battery. The battery tray slides right out, just make sure you pull the draining hose gently. You need to remove all of the above so you can remove the screws holding the frame that hold battery, ECU and all electronic.
Note: you do not need to remove everything, just enough so that you can move the battery frame out of the way. I did remove the ECU to give me more free play with the rest of the wiring. I also loosened some of the electronics components for the same reason but I did that without actually unplug anything other than the ECU.

Now you can remove the coil (hold in place with one nut) and remove the spark plug of the vertical cylinder. The horizontal cylinder is a lot easier, just carefully undo the coil and remove the spark plug. Now you can rotate the engine to the TDC of the horizontal cylinder. This is marked on the timing gear on the engine axle (as opposed to the ones on the cams's heads). Just align the markings and you will see that the inside of the timing gears on the head of the vertical cylinder align, they look like two T laying to the side pointing aft. See photo.

Now mark the belts. I suggest you watch the video from California Cycle Work on Youtube for this step. The link again http://www.youtube.com/user/cacycleworksdotcom

Note: the vertical belt is the tricky one, I suggest you make marking on the first visible tooth on both sides of the belt at the engine shaft gear. This will come in handy as you may want to move the engine back and forth a little to allow the new (and stiff) belt to bite where you want them. I aligned those markings first and then I applied tension on the belt as I worked my way to the head.

Note: to install the belt I recommend replacing the movable belt tensioner, install and align all markings on the belt and then put the movable tensioner back. I did this for both belts and it worked like a charm.

Now you are ready to tension the belts, follow the procedure in the video and, for good measure, rotate the engine several times by hands once you are done to make sure everything runs smoothly. Check the TDC of the horizontal cylinder by using the marking on the engine gear axle and the alignment of the T shaped inside of the heads gears.


Check the valves clearances
Remove the head covers. I would do one at the time. Note that once you remove all screws, the head will sit tight. Use a long flat screwdriver and a rubber mullet and gently (I mean gently!) tap the head covers upwards sticking the screwdriver between the head gears. Once the seal is loose, pry the head off by hands carefully. Now the four valves and the two desmodromic cams are visible (see photo). Use a feeler to check the clearances of the opening rockets and the closing rockets. Ducati recommends that you check the opening rocker right where the shim meet the rocker and the closing where the rocker meets the cam.

NOTE: Obviously you have to put the cylinder you are working on on TDC!!!

If the clearances are off, you will need to do the unthinkable, you need to remove the four bolts that hold the cam in place and remove the cam. This will give you access to the shims.

Note: my engine was within tolerances so I actually did not had to do this step. If you do have to do this, obviously you need to remove the belts. Before you do so, do make sure you mark the belt. You need not to worry about the cams rotating since there is not pressure on them when the piston is at TDC.

Note: to remove the horizontal cylinder head cover, you will need to remove the radiator. Simply empty the system, loosen the hoses that connects to it and carefully locate the electrical plug for each fan. They are located one per side and rather hidden. I am showing the left one in the photo, check it out. Once you disconnect the fans and disconnects the hoses, there is only one screw holding the radiator in place. Remove it. Now very carefully remove the radiator. I suggest to remove the air scoop under the lower triple clamp to prevent from scratching the radiator or cutting yourself on it! Not that the radiator is remarkably delicate!!!! I did manage to bent one of the supports just by laying down in a cradle.

1 comment:

  1. That isn't a Desmoquattro motor, it's a Testastretta.

    ReplyDelete