'00 M750 Motor Making Most Unpleasant Noises

[Raziel]

Thanks Mitt I will have to look at it again, it seemed as though the difference b/w the two marks in the sight glass resulted in 180 degrees difference on the pulleys, but I obviously need to take a closer look. Even so...

The fact that the horizontal pulley won't spin all the way around (dependent on piston position) is a problem.

So... both pulleys should rotate 360 regardless of piston positions? Back to the bent valve/damaged valve guide scenario. 

I assume that just because the vertical cylinder pulley can spin 360 (haven't checked it in all positions) doesn't guarantee there's no damage there either.

Time for some research. I've got the Haynes 91-96 2-valve manual and the Ducati shop manual and will look for other resources. What else could be done before the head is removed for inspection? It doesn't seem like you'd be able to tell much by looking at the valves from the rocker side unless the damage were pretty severe, but it seems like the obvious next step.

[ducpainter]

It's time for the heads to come off.

Sorry.

[mitt]

I still think that the timing and valves are OK.  Why do you think the heads need to come off?  The cams should not be able to spin at TDC - that is normal.  If you can get them to spin when the cylinder is a bottom, then they are OK.

Rather than spinning the cams separately, I like to pull the plugs, put the belts on - making sure all the pulley tick marks are lined up like in the OP's original photos, and then using a crank turning tool, with the plugs out, and bike in neutral, gently spin the engine and feel the pressure or suction on the plug holes with a finger to see if your strokes are inline with a 4 stroke cycle.

mitt

[Porsche Monkey]

I agree with Mitt. The cams were off but so was the layshaft.  I would remove the plugs, back the motor up to where the layshaft lines up and try to turn the cam through on the horizontal cylinder. On my bike it will turn all the way through in this position. If it doesn't bind put the belts back on and check compression. Good compression = straight valves. 

[Howie]

I agree with Mitt. The cams were off but so was the layshaft.  I would remove the plugs, back the motor up to where the layshaft lines up and try to turn the cam through on the horizontal cylinder. On my bike it will turn all the way through in this position. If it doesn't bind put the belts back on and check compression. Good compression = straight valves. 

[Porsche Monkey]

I just want Ole Grumpy to be wrong. 

[greenmonster]

I agree with Mitt. The cams were off but so was the layshaft.  I would remove the plugs, back the motor up to where the layshaft lines up and try to turn the cam through on the horizontal cylinder. On my bike it will turn all the way through in this position. If it doesn't bind put the belts back on and check compression. Good compression = straight valves.

+1.

Simplest way, I think:
Move pistons til none of the 2 is near TDC, just feel that w a screwdriver. Remove belts.
If both pulleys rotate 360, put belts back & check compression.
If that`s good, you`re fine.

[ducpainter]

I still think that the timing and valves are OK.  Why do you think the heads need to come off?  The cams should not be able to spin at TDC - that is normal.  If you can get them to spin when the cylinder is a bottom, then they are OK.

Rather than spinning the cams separately, I like to pull the plugs, put the belts on - making sure all the pulley tick marks are lined up like in the OP's original photos, and then using a crank turning tool, with the plugs out, and bike in neutral, gently spin the engine and feel the pressure or suction on the plug holes with a finger to see if your strokes are inline with a 4 stroke cycle.

mitt

If the cam won't rotate 360⁰ with the piston at TDC what is the obstruction?

I just want Ole Grumpy to be wrong.  

I want to be wrong in this instance.

You could line up the marks...don't worry about tdc...just line up the layshaft mark and see if the upper pulleys line up with their respective marks.

If they do then pull the valve covers on the horizontal cylinder and check to see if you have a loose valve clearance. Chances are it will be very loose if there is the problem I think there is.

If they don't then pulling the head would be in order IMO.

[mitt]

If the cam won't rotate 360⁰ with the piston at TDC what is the obstruction?
I want to be wrong in this instance.

At TDC, the piston is at the top of its stroke - it should hit the valves at TDC...

I just changed my belts 2 weeks ago, so this is still somewhat fresh in my gray matter.  My horizontal cam will not turn much when I have all the pulley tick marks lined up.

Agreed with the suggestion of using a piece of stiff wire or something to feel through the spark plug hole and the OP get familiar when the piston is at the top or bottom of stroke, intake, exhaust, and compression order for each cylinder.

mitt

[ducpainter]

You guys all may be right after re-reading.

I've been wrong before, and in this case I hope I am.

To the OP, did you change your belts before this 'noise' appeared?

Also, how is the bike running? Normal power and all?

[hiero]

...
Also, how is the bike running? Normal power and all?

good question, how is the bike running?  pretty much all the issues that have been talked about would give you either a no-start, or serious performance issues...

[OT_Ducati]

had loose flywheelnut on my 99' 750.
funny noises good power still.
flywheel ground the pointer in the window alittle.

[Raziel]

Wow! Quite a lot of excellent posts to go through and all with good information! Thank you most kindly everybody. I have no interest in proving "Grumpy" wrong, but yeah, I hope you're wrong too mate! I appreciate your help.

had loose flywheelnut on my 99' 750.
funny noises good power still.
flywheel ground the pointer in the window alittle.

I'm leaning toward this idea as it meets everything I've observed above and confirms that it's possible.

It was the minor cacaphony of clinks and clanks that accompanied me on the ride home from work which started this whole thing, and the bike hasn't been run since. I didn't feel any change in revs, torque, pull, etc. while doing so, though I was most def babying her those few miles. Apart from the noises it seemed to be running fine.

But at this point, I have no plans to button her back up and start her again until I know with certainty that I have the cam pulleys in their proper position relative to the crank for fear of doing new or further damage, and I am not confident I understand the stations well enough to be sure that I now have everything in its proper place after having fiddled around so much. I need to understand the relative positions of the pistons that Mitt referenced before doing so. I need to know the proper baseline to check the amount of pulley travel between TDC's.

I'd like to understand the mechanics of the travel...please forgive my ignorance but I must learn this and if anyone would like to share their knowledge it would help me immensely. Here are my questions:

A. One 360 degree revolution of the main pulley/layshaft/crank from TDC = what? One half of the 4 stroke cycle? I.e.,  suck and squeeze on one full revolution, and bang and blow, on the second? Or the full 4 strokes in one 360 degree revolution? Also, Mitt has written that the case marking for this pulley indicates TDC for the rear/vertical cylinder. One can then assume that the cam pulleys should be set by rear cylinder TDC, and suggests the full four strokes in a single revolution.

B. What does a 360 degree revolution of each cam pulley accomplish? Half, or the full four stroke cycle? From what I gather a full cycle would be one extension and one retraction of each valve per head, each cycle.

So I am grasping for straws a bit, but I can learn quickly through explanation. If it must learn this empirically by checking piston position with a screwdriver through the spark plug holes as has been suggested, that's no problem, but understanding where the individual components are expected to be during their respective cycles, and the frequency of said cycles vis a vis pulley position, would greatly help me to understand what I am observing.

And if there is a shortcut or easier means of getting it through my thick skull, I'm all ears. Thanks again all.

[ducpainter]

My advice with regard to belt timing is not to over think it.

Line up the layshaft mark on the case and see if the cam pulleys line up with their respective marks. Crank position is automagically in the right place. It is designed that way.

If they do you have no belt issue...if not...pull the valve covers and check for a really loose valve clearance.

If they do line up it could be a multitude of problems.

[hiero]

as far as a quick thing you could check to see if the flywheel nut is loose, don't ask me why, but the clutch pushrod is usually broken, sheared in one spot into two pieces.  Something to do with increased vibrations or some other magic thing, but it's a good sign that's super easy to check without having to tear open the side casecover...

I know, it sounds completely unrelated, but worth at least a looksee...