Ducati.org forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
Hello there. I have an issue with my 900ss, and I'm uncertain as to how to proceed...


Long story short, the timing belt on my vertical cylinder failed and my piston and valves high-fived each other. Naturally, they bent and needed to be replaced, which I did myself. I'm pretty sure I have everything back together correctly, but I'm at a loss as to how to get the timing correct. The horizontal cylinder is still fine (though that belt is getting replaced when the other one does).


Does anyone have any advice on this? I don't have the multiple hundreds of dollars to take it to a Duc shop, and it's much less fun to sit in my dining room making vroom noises than actually riding...
thanks in advance!
 

·
Registered
Joined
·
240 Posts
Personally, timing is such a critical thing, I'd review the ENTIRE following procedures in this link:
Ducati Suite- Advanced Maintenance


As you are replacing a belt from a cylinder that lunched itself, you'll want to make sure that the timing is spot on. That will mean finding TDC for that cylinder and making sure the cam is correctly set for that cylinder.



This must be done in correlation to, and in conjunction with the undamaged cylinder. This is why I'd review the entire procedure in the link.



Further, I'd also review brad's take on the procedure:
Brad The Bike Boy: Ducati timing belt replacement, factory tool and cam timing ramblings


The gist is that both use the TDC point to adjust the valves which you'll need to use to get your timing set.......sean
 

·
Registered
Joined
·
6,783 Posts
The valve/cam timing is relatively simple to set on these models, being single overhead cams (SOHC). Assuming nothing else was damaged or disturbed with the blow up, simply lining up the three pulleys with the provided marks sets the cams correctly.
So you rotate the engine in its correct direction (the same direction the wheels turn when going forwards) bearing in mind that the cam pulleys rotate in the opposite direction.
You need to line up the dot on the lower (driving) pulley with the mark on the crankcase, at about 7 o'clock.
There are raised 'tits' on the edge of the rubber part that surrounds the upper (head) pulleys, which need to line up with the dots on those pulleys (at about 11 o'clock if checked on the rear head).
You will need the correct socket to hold the rear head's camshaft against the valve spring's detent as you position the belt to the correct teeth. But you will have needed one of these to dismantle the camshaft.
It might take a few attempts to get this correct. Recheck the dots line up after you have set the belt tension.
All pretty straightforward. The tensioning of the belts is less straightforward, and requires some care, or experience. Basically if it is too tight it will whine, and you might break another one! Too loose and there will be rubber dust everywhere next time you look in there...
Once you are happy with the tension on those you should be safe to start it up. Bear in mind that belt tension needs to be checked/retensioned after about 600 miles after new belts have been fitted.
But I have some concerns that you are unclear on these basic operations when you have done this work on the head and piston!
I also have concerns about damage further in following the belt failure - conrod and big-end bearing, for example. Not always economically wise to do these repairs on your own bike without suitable experience.
Hope it works out OK...
 

·
Registered
Joined
·
14 Posts
The other thing that often happens when valves get bent is that the valve guides can crack if they are cast iron. I've never seen rod, piston or bearing failure following an "entanglement" but almost always cracked guides.
 
1 - 5 of 5 Posts
Top