Hi, The tachometer cable on my 750ss 1998 broke, so I bought new one. I installed it to discover that the engine is not turning the cable. What is the problem?
Thanks Viv.........:Kiss: This could be the worst case scenario.......... But it might just be the silly nut on the end of the camshaft needs tightening; however, I would certainly pull the drive pinion out to have a look at it.........if it looks like mine, then get yourself a very small torch and a small mirror. Remove the allen bolt that holds the pinion boss in the head, then have a real good look down the hole.......you will just about be able to see the edge of the worm gear teeth (about three of them IIRC).
See the pic below...........I assume you are working on the arrowed item........ignore the black knurled cap......I used that to stop oil from coming out after I had removed the faulty drive pinion. If you have removed the allen bolt, you could try tapping the lug of the boss in a rotary direction to loosen it......use something like a wooden dowel because the boss is brass (I have a spare boss if you bugger it up, though). If you can budge it, try twisting it around as you remove it, because you have to disengage the pinion teeth from the worm drive as you pull upwards. NB, when you put it back in, don't knock it in.......rotate it again. Depending what you find, I can give you an indication of how to deal with it......however, if you need to employ a local garage to get the boss out, you might find you need some help doing a repair........it all depends if it is damaged or not.
The one you can't see in my photo above because I have already removed it.......... When you have the belt cover off it will be apparent.........but you will need to buy or make a socket to be able to turn it, plus something to stop the cam from turning while you do it. See pic below....
Ok managed to remove the allen bolt on the brass boss. It also moves but I'm unable to extract it. If I twist it, it catches on the housing of the timing belt.
Can you get anything thin (like a sharp chisel) under the lug of the boss to get it moving upwards/out?.......There is an O ring around the boss which might be enough to be holding it in......see pic.....
Hi, Quite pround of myself. (not being a mechanic). Got the brass boss out to find that 2 teeth are missing. I assume that they have ended up in the oil filter? The cog does not turn. That can't be correct can it?
If mine was pushed right into the boss there wouldn't be a gap.........so the two are identical. I suggest you now enlist the help of a friend. Stick the bike on a rear paddock stand. Take the spark plugs out. Take the belt covers off (so you can check the silly nut and give you a bit more room) Get the small mirror and a small torch. Put the bike on second gear (or if you can turn the drive pulley for both cams and get your helper to gently turn the engine while you are looking in the mirror using the torch for light...........you should be able to just see the central worm gear teeth down the hole where the boss is fitted.........the teeth will be right at the bottom rearside of the hole. If that gear looks as though it is damaged, then you will need to change both the pinion and the worm gear. Available from Ducati as a kit (and now fairly expensive I reckon, although it wasn't too bad when I got mine five years ago (£40)). If you can get a good secondhand pinion, you still need to find out why the other one broke......The silly nut being too loose is my best guess. If you fit the pinion, do not knock it in..........that's one way of breaking them. Turn the engine over by hand to see if it rotates as it should. You may be lucky with the broken bits and find them in the lower valve cover if you take that off........there could be other particles they will most likely be on the magnetic sump plug, so change the oil anyway. If you have to change the worm gear, I can give you instructions if you think you can do it yourself.
Thanks for the reply, will probably take a while. Need to buy paddock stand and mirror. Really appreciate all the help. I'll let you know something in a few days.
Very funny....looks like I'll have to steal Mrs Woodbine's. Couple more questions: Where do you order you Ducati parts? What is the name of the kit for the pinion and worm gear? If I'm going second hand with the pinion, what would be the key word/name of the part?
When I want genuine Ducati new parts, I use MotoRapido in Winchester (speak to Craig). They will make sure you get the right ones. Tacho drive gear kit. Second hand: Be careful........not all the pinion drives available are the right ratio. You need one specific to your bike, although I think the 600 and 900 will fit as well. Try asking on the Wanted forum if anyone has a spare. The image below is for a 1996 - 1997 750SS (I suspect yours is the same)...........It should give you a clue as to how it works etc.
PS......Bearing in mind you appear to be in France, you could always get your parts from: Stein-Dinse GmbH Online-Shop And if you feel that changing the worm gear is too hard a job, you could fit an electronic tacho..........the cost might be about the same overall. It seems the 900 drive kit is 191 Euros........(I think it is the same part). If you have to replace the worm gear, what you will need at least, is the following: Silly nut socket (make one instead of buying it??) Tool to hold cam pulley still while you are loosening or tightening the silly nut. Tacho drive gear kit (both Items 41) Oil seal (Item 42) Bearing (Item 40…….I doubt if you can remove this without damage) Gaskets (Item 19 x 2) Gasket (Item 35……….you will need to remove the cam to get the bearing 40 out) Silly nut (Item 3)
