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Discussion Starter #1
So I am on the last leg with my engine rebuild ... just waiting on a torque adapter to to put the heads back on ...but what I dont know is how I am going to do the timing and reinstalling the belts. Got some good tips on how to tension the belts but no idea how to get the timing right ... As far as I can tell the only timing mark on the 749 is the reference on the clutch sidecase that matches with the engine belt pulley. That gives me horiz. cyl at TDC ... but where do I go from there ??? :)

As a side note I have not done anything to the heads Once they are on and the belts are on I am going to change the rubber gasket on the top cover of the head as that was leaking when the engine was working but other than that the heads remain untouched.

Cant find a good tutorial on how to do the timing ...

So once again any assistance, comments and tips are welcome.

Migrane
 

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Discussion Starter #3
Did you figure out the squish and head gasket size?

IDK how to put the motor back together again without taking the valve covers off and reading the cam's and matching them to TDC. Its a bit of a chore. You're suppose to mark the cam position before taking it apart... ;)
I did some markings but I don't know if they are ok ... cos I marked the pulley and the belt but not on the case ... smart ! I know ... so ... the question still remains ... how do I go about this

I got original head gaskets and all that jazz so I can just go with the values in the workshop manual.

Migrane.
 

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Discussion Starter #5
Well, it sounds like you might be OK. If you marked the pulleys, what reference mark on the case did you use? Most people use the valve cover crack. I mean, sounds like you should be able to just re-align the marks...

Also, head gaskets shouldn't be re-used... thats why I asked. ;)
LOL :)

my bad ... when i was sayin' "I got original head gaskets ... "
I meant that I bought some new Ducati original head gaskets as opposed to going with the aftermarket copper gaskets.

I dont really trust my marks and I didnt mark the case just the belts and the pulleys ...

I already know this is going to be some of that Voodoo Ducati stuff :abduct: ... but I gots to figure it out ...

Migrane
 

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Ducati uses a jig to set Testastretta cams. IIRC, TDC is indicated by the "T" in both cams inverted. That will get one head set for you.. I'll check my shop manual tonight to see if I can get you something more definitve
 

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Here you go!



#12
OldFart
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Join Date: Mar 2004
Posts: 746

Getting the cam timing correct is relatively easy.
FIRST, take the belts and valve covers off to insure that no valves are in the open condition. This as when you rotate the engine you won't clobber the valves with the pistons.

Rotate the cams by hand to check for any binding with the belts off and pistons down in the bore somewhat. Check your valve clearance if you can. A reduced closer clearance or increased opener clearance may signify a bent valve.

For the front cylinder rotate the engine until the yellow dot on the lower drive pulley is in line with the (very fine) line on the engine case. This is TDC compression for the front cyl.

It's true that the marks on the cam pulleys don't mean anything. These pulleys are used on many different models. On model XX these marks are probably relevent, but not on the Testastrettas. The marks are just going along for the ride.

Now... Look at the end of the cams where the big nut holds the pulley on.
The end of the cams are machined with grooves about 5mm wide. These resemble a T.

With the front cyl on TDC, these marks should resemble an inverted T. The groove that does not go all the way across the cam faces upward. The groove that goes all the way across the cam end is aligned with the head surface. Put the belt on. * When the belt is on, these grooves will not be perfectly aligned with the head surface. (They) will be offset one way or another a little bit due to how the partiular cam was degreed in at the factory. Not to worry, the tooth spacing on the belt will position them correctly. It's easy to get one or both cams off by a tooth (as my dealer did and my bike ran like schitt) so fiddle wih it a while until the cams are as close to parrallel to the head surface as they can be.

For the rear cyl, get it to TDC. If you don't have a dial indicator to work with in the plug hole, you can use a 8 or 9mm wood dowel to feel the piston coming uphill. Wood will not damage the plug threads. Keep wiggling the stick slightly as you turn the engine so it will not cock sideways and jam in the plug hole. Turn the engine slowly until you are at "stick" TDC, then confirm TDC with the timing mark through the window on the alternator.

Same thing with the cams. Inverted T cam end appearance with the single groove up. Install the belt.
I used a few touches of wifeypoo's red nail polish to make my own marks on the pulleys and head surface for future reference.

Don't panic with all this description stuff, just go through it slowly step by step.
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02 998 la strega bella
Last edited by OldFart : Apr 11th, 2007 at 1:23 pm. Reason: typo
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Discussion Starter #9
Here you go!



#12
OldFart
Senior Member

Join Date: Mar 2004
Posts: 746

Getting the cam timing correct is relatively easy.
FIRST, take the belts and valve covers off to insure that no valves are in the open condition. This as when you rotate the engine you won't clobber the valves with the pistons.

Rotate the cams by hand to check for any binding with the belts off and pistons down in the bore somewhat. Check your valve clearance if you can. A reduced closer clearance or increased opener clearance may signify a bent valve.

For the front cylinder rotate the engine until the yellow dot on the lower drive pulley is in line with the (very fine) line on the engine case. This is TDC compression for the front cyl.

It's true that the marks on the cam pulleys don't mean anything. These pulleys are used on many different models. On model XX these marks are probably relevent, but not on the Testastrettas. The marks are just going along for the ride.

Now... Look at the end of the cams where the big nut holds the pulley on.
The end of the cams are machined with grooves about 5mm wide. These resemble a T.

With the front cyl on TDC, these marks should resemble an inverted T. The groove that does not go all the way across the cam faces upward. The groove that goes all the way across the cam end is aligned with the head surface. Put the belt on. * When the belt is on, these grooves will not be perfectly aligned with the head surface. (They) will be offset one way or another a little bit due to how the partiular cam was degreed in at the factory. Not to worry, the tooth spacing on the belt will position them correctly. It's easy to get one or both cams off by a tooth (as my dealer did and my bike ran like schitt) so fiddle wih it a while until the cams are as close to parrallel to the head surface as they can be.

For the rear cyl, get it to TDC. If you don't have a dial indicator to work with in the plug hole, you can use a 8 or 9mm wood dowel to feel the piston coming uphill. Wood will not damage the plug threads. Keep wiggling the stick slightly as you turn the engine so it will not cock sideways and jam in the plug hole. Turn the engine slowly until you are at "stick" TDC, then confirm TDC with the timing mark through the window on the alternator.

Same thing with the cams. Inverted T cam end appearance with the single groove up. Install the belt.
I used a few touches of wifeypoo's red nail polish to make my own marks on the pulleys and head surface for future reference.

Don't panic with all this description stuff, just go through it slowly step by step.
__________________
02 998 la strega bella
Last edited by OldFart : Apr 11th, 2007 at 1:23 pm. Reason: typo
OldFart is offline Report Post Reply With Quote


Thanks !!! That makes sense ... I'll try to see if I can actually do it when I am in front of the engine ... Got a printout of your post and I'm walking to the engine

Migrane
 

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Discussion Starter #10
Eureka

Damn this is good ... I put the pulleys in the position you recommended and they line up with the marks I made on the belts and I also figured what I need to do to establish TDC on both cyl.

On the horizontal cyl there is the mark on the pulley that drives the belt which aligns with the notch on the clutch sidecase.

And on the vertical cylinder one needes to pop out the little plug on the alternator cover and the mark on the flywheel becomes visible ... when the mark is in the middle of the plug hole you got TDC on the vertical cyl ... :)

Well this gives me the necessary confidence to continue. I already figured the belt tensioning so I will do that and put some new spark plugs in and this baby should sing ...


;)

Thanks again

Migrane

Now only if my damn torque adapter would be here this would not be a wasted weekend ... :(
 
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