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Discussion Starter · #1 ·
I'm at TDC as shown by the mark on the crank through the window and I put a hanger in the plug hole to see where it is at it's highest point... but the marks on the cam pulleys are both at the 2 o'clock position relative to the mark on the case... What would cause this???

As a side question... could this explain why I'm having flaking rockers at only 3200 miles? Also zero valve clearance for my opening intake valves... The bike is a '02 748 with 3200 miles...
 

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Discussion Starter · #3 ·
yep... compression stroke. It's only the vertical cylinder that doesn't line up on the cam marks. The horizontal is in sync with the cams marks and TDC
 

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Discussion Starter · #5 ·
I do have a service mark and it always says when checking valve clearance, set cam marks to TDC. I also just realized that at TDC as show by my cams... valve clearances are way off so when I go by TDC of the piston with a wire and mark on the crank, everything is in spec. So why would these marks be so off?
 

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Discussion Starter · #7 ·
ok... you gotta explain this to me... why put marks on a cam to show TDC if it's not really TDC? I'm at a loss...
 

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Mr Leakered
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Get LT's manual or got to the Hall of Wisdom and read over the valve adjust posts in detail. That is what I did after my initial measurements were not going well. I will become very straight forward.

I understand that you found some significant issues with this service. That stress is not a good thing to deal with when you are working with thousanths of an inch.

The TDC mark on the flywheel and cam pulleys are there to ensure your belts are installed correctly. The horizontal cylinder will be at TDC, the vert will be on lobe. So, it will be a bit of a challenge to get the belt on properly.

After you torque the belts, re-check the marks and turn the engine by hand a few revs just to be sure there are no clashes and everything is in line.

You should be replacing the belts on an 02 anyway. So, like Tye said, there's no reason to keep them on and complicate the job.

Have a good one.
 

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Discussion Starter · #10 ·
I'm not having troubles measuring valves or any of that... I'm just wondering why the cam marks don't line up when the piston is at TDC? Was the guy at the ducati factory hungover that day? Should I pull the pulleys to line up the marks?
 

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The marks on the pulleys are there for getting the timing on the pulleys lined up. On the vertical cylinder the marks do not line up at TDC. I believe they do on the horizontal cylinder, but really you should check the marks on the flywheel to get TDC on the piston. The marks on the cam pulleys were never intended to be used for TDC determination, the mark on the flywheel is directly connected to the crankshaft as is a much more accurate measurement. Just make sure all the dots on the pulleys are lined up with the marks on the cases and you are good to go.

Mike
 

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Discussion Starter · #12 ·
Reason I'm concerned is I'm getting ready to pull my cams... which means belts and all come off... seeing as how the marks on the vertical cams don't line up to be at TDC... then when I put my cams back in, they will be off... see my frustration. How will I get the timing of the crank and cams lined up?
 

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Mr Leakered
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If you're cams are off by a tooth, I've heard that the bike will run, but run quite crappily (that's a real word ;) ).

If you think they are correct, belts with H and V and their rotation direction as well as a mark at the three locations for each cam pulley on each belt, preferably at the allignment marks.

You will then be able to reinstall them and match up the marks. If you are replacing the belts, like you should at this age, you can transfer all the marks to the new belts. Double check by counting teeth to ensure you're good to go.

As noted before, rotate the engine by hand without the plugs to ensure there are no clashes.

Have a good one.
 

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The cam pulleys are registered to the cam with a key, there is no worries about alignment on reassembly. The cam timing can be adjusted with offset keys. The vertical cylinder is not at TDC when the timing marks are lined up, only the horizontal cylinder is at TDC at that time.
 

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Silly question, are you sure you have the TDC mark on the flywheel and not the other mark for firing timing position? There are two marks on the wlywheel ;)

You may just be looking at the wrong one, and they are only a few degrees out from each other.

MF
 

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The cam timing will be correct when all the dots line up on the crank pulley and the cam pulleys. You dont have to worry about the piston timing. The piston position is related to the orientation of the crank pulley. That relationship is fixed, you cant change it.

I set the piston to TDC using a long thin screwdriver through the spark plug hole. I bring the piston up on the compression stroke. At the top of the stroke I check the timing mark on the flywheel to know I am at TDC. Actually if you are slightly off, it doesnt matter cause the valves are closed for a duration. I check the valves, if they need adjusting, I then remove the belts and change out shims. I make sure to keep the piston at TDC so a valve wont drop into the combustion chamber. On the Desmoquattros, you have to remove the cams or at least pull them out slightly to slide the openinig rocker out of the way. I remove the cams completely as you have more room to work.

After valves are adjusted and checked I put on the new belts. I dont have the tool that holds the two cam pulleys on the head, so on the vertical cylinder I actually turn the engine so the crank pulley moves in the CCW direction about 5 teeth. I then rotate both head cam pulleys the same amount and then put the belts on. I then rotate the engine 5 teeth to make sure all the dots line up. Its easy to get off by one tooth, so make sure you check your cam timing carefully. Cams rotated by 5 teeth avoids dealing with the return spring that wants to rotate the cam pulleys when trying to put the belts on.

Mike
 

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The cam timing will be correct when all the dots line up on the crank pulley and the cam pulleys. You dont have to worry about the piston timing. The piston position is related to the orientation of the crank pulley. That relationship is fixed, you cant change it.
Exactly and its why I said earlier, don't worry about it... As long as the crank marker and timing shaft are aligned to the dots (pretty easy to figure out), you're all set, you can pull the bike apart and put it back together again. Even if you were to turn the crank for some reason, all ya gotta do is re-align the dots. ;)

Its one reason why Ducati's are so easy to work on, they make it pretty much kiddy play :) Imagine changing the timing chain on a R6... talk about total motor re-build.



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Discussion Starter · #18 ·
So while we are on this topic... what am I looking for to see if my cams have damage? Besides cracks and such... I can see where the lobes have chrome deposited on them from the rockers (yes rockers are getting redone) so should I use steel wood to sand off the chrome on the cam? At 3200 miles my rockers should not be flaking so bad so I'm worried it might be cam related.
 

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Rocker flaking has to do with model year (bad production) and poor clearances. It really doesn't have anything to do with the cam itself, even if your cam's are not smooth.

In terms of your cam's, what you consider to be "chrome" is actually a wear mark where the cam has lost its natural color. Almost all desmoquattro's suffer this problem and its not a problem if you rub your finger across it and its smooth. Sometimes the rockers get so bad, the chrome is missing and the material underneath is what the cam hits and pretty much tears the cam's up. You can feel that with a quick swipe of your finger.



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There is a specific number of teeth between each "dot" that you can use to line everything up:



You can read all about my experience getting the belts on and properly tensioned. There are links to good writeups.
 
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