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Discussion Starter · #1 ·
Hey.

Two months ago I had a small accident, drove into a ditch, nothing major, engine idled for about a min while the bike was laying on the ground. Now, I started the bike for the first time in those two months. Worked fine, except there was some weird noise from the horizontal cylinder. Kind of like a clunk? Anyways, I stopped the engine and pressed the started button for a sec, a spark came from the starter relay. I assume this is unusual? What may cause this?

Next: I pulled the belt covers, found out that the belt for the horizontal cylinder is quite worn. I have attached a picture showing the wear. The vertical belt looks quite okay, there is no wear. I checked the belts ~2000km ago and they were both fine. It seems like the worn belt has rubbed against something which has caused the wear. Also, there are some "rips" or worn patches on the outside of the belt. I assume that this kind of uneven wear is also unusual. Anyone have similar experiences?
 

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The belt appears to not be centered and though I can’t see the belt damage, I will take your word for it. I’d remove the belt and check the tensioner bearings and cam bearings. Something is causing the damage. I wouldn’t run it until I found the cause.
 

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Discussion Starter · #3 ·
You can see that the belt is worn from the side. Something has ground off about 2mm's of material.

How can I check the bearings? See if there is any play in them?
 

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You can see that the belt is worn from the side. Something has ground off about 2mm's of material.

How can I check the bearings? See if there is any play in them?
Yes, check for play. Also look and see what might be pushing the belt towards the engine, if anything is bent. Turning the engine over by hand with the belt cover off should show you where it is rubbing and may give you an idea what's going on.

Look closely at your belt covers to make sure nothing is wrong... if you hit a cover in your accident maybe it is pushed in somehow and contacting the belt? I would definitely figure this one out before starting the motor. Take the belt off, and turn the idler and tension pulleys by hand, make sure they turn freely and do not have excessive play, and that they do not look bent. Also turn the camshaft gear and make sure it is not bent or does not have excessive runout or play.
 

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It looks like something pushed the belt so that it rubbed on the inside. Perhaps when it was running on the side something pushed on the cover and forced the belt in? Remove the plugs, raise the rear, put the bike in gear and rotate the wheel to move the belts pulleys and valve gear. Look to see if there is any interference or noise from the idler pulleys. You can check out California Cycleworks YouTube video for replacing the belts to see what to do to remove and replace the belts. While off, make sure the pulleys run true and don't look like there is anything worn. The idler pulley bearings do wear and fail.
 

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You need to check the idler rollers - particularly the one with the dual bearings (on the adjuster) as rollers. If one of those seizes, it can get messy...



Take the whole adjuster off, and check the bearings individually for any resistance.
 

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Discussion Starter · #7 ·
You need to check the idler rollers - particularly the one with the dual bearings (on the adjuster) as rollers. If one of those seizes, it can get messy...



Take the whole adjuster off, and check the bearings individually for any resistance.
The idler roller is the tensioner, correct?
 

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The roller opposite the tensioner. Just check all of it.
 
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Hard to tell from the picture but if anything it looks like the belt was rubbing on something on the inside run. Inspect for anything that may have contacted the belt as it spins. Did it break a belt cover? if not I do not see this as being due to the crash. I do not see bearing or belt damage from a bad bearing in the picture shown. As bearings fail they stop turning usually and then the belt will get shiny from sliding over the non-rotating bearing. You can still read the writing on his belt so it has not suffered damage to the surface just the side.

You would be crazy NOT to check everything including all bearings at this point, I will include belt timing. If the belt jumped time a tooth because it was too loose then you may be smashing a valve into the piston, this can get catastrophic fast so do not take the chance and check it. If you compare the two belts the one shown is narrower by how much? There is no sign of it wearing on the outer run and some belts are MADE with one side showing cords so compare the two. If there is something allowing the belt to wander on the pulley it may be contacting something. As others have said turn the motor over by hand once you have verified cam timing.

If you fell on the right side be sure to inspect your clutch, if the cover was bent inwards you may be hitting your clutch springs/perches which will break them. Pull the cover and check if it is dented at all.
 

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Hard to tell from the picture but if anything it looks like the belt was rubbing on something on the inside run. Inspect for anything that may have contacted the belt as it spins. Did it break a belt cover? if not I do not see this as being due to the crash. I do not see bearing or belt damage from a bad bearing in the picture shown. As bearings fail they stop turning usually and then the belt will get shiny from sliding over the non-rotating bearing. You can still read the writing on his belt so it has not suffered damage to the surface just the side.

You would be crazy NOT to check everything including all bearings at this point, I will include belt timing. If the belt jumped time a tooth because it was too loose then you may be smashing a valve into the piston, this can get catastrophic fast so do not take the chance and check it. If you compare the two belts the one shown is narrower by how much? There is no sign of it wearing on the outer run and some belts are MADE with one side showing cords so compare the two. If there is something allowing the belt to wander on the pulley it may be contacting something. As others have said turn the motor over by hand once you have verified cam timing.

If you fell on the right side be sure to inspect your clutch, if the cover was bent inwards you may be hitting your clutch springs/perches which will break them. Pull the cover and check if it is dented at all.

I looked at the OP's picture a little closer - I think you're right. In fact to me, it looks like there may have been something (stone, nut?) that's gotten inside the cam belt housing, and been rubbing on that front (upper) pulley - judging by the metal debris.

One other thing to check - the black 'blanking' plug (that's the large black plasticky looking stuff behind both the upper/top cam pulleys that blocks off the engine fins - mine bent itself outwards, and into contact with the cam belt, until it dropped a bit off, and chewed up the belt. NOT what caused the failure in my picture above - THAT was one of the two bearing/rollers on the tensioner/adjuster seizing.
 
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The idler roller is the tensioner, correct?
I ended up replacing ALL the rollers - to be sure. Note the ones opposite the tensioner are quite pricey, and (AFAIK) don't have a non-Ducati equivalent. The double bearings/roller on the adjuster/tensioner are available - but you need to make sure of the bearing code - IIRC it should end in 'C3' which is a looser tolerance for high speed/temps.

I got real lucky when my belt snapped, as it didn't touch any valves. It just dropped to one cylinder, and I was able to limp home. Just.
 

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If you can find a number on it, you can buy an equivalent. Sometimes the bearing number is etched on the edge of the shell, very tiny print. But, even if you can’t find a number, carefully measure the I.d, o.d, width, and either take it to an industrial supply place or look online, places like MSC and McMaster- Carr.
 

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Discussion Starter · #13 ·
I managed to get the belts off now and soon will get replacements. Stripped the tensioner bolts again even though I got the strongest ones available.
I ran the motor around and it didn't seem like the belts were rubbing against anything, no weird sounds from the engine too. The belt hadn't jumped a tooth. However, when I first removed the belt covers there was indeed a lot of dust and sand and a small metal(?) shaving in there.

The bearings seem fine, they all rotate pretty well and have no play in them. However, one of the vertical cylinders tensioner's bearing is a bit tight when rotated alone. But when both are turned, they move great. Should I replace them asap? Does anyone know the dimensions of the bearings?

Another thing I noticed was that the cam pulleys need a bit of force to do a rotation, then they kinda snap and move freely until the next rotation. Like there is some sort of a spring. Normal?
 

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There are light "closer" springs on the Desmo valves. They ensure that the valves close all the way for easier starting (compression at low cranking speeds). This is the snap that you're feeling.
 

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I am not sure how you are stripping any bolts, if you tighten them to the specified torque they should last a lifetime. If you mean you are chewing up the bolt HEADS, then buy a proper 6-sided socket. Don't tighten beyond the specified torque, and make sure you use a medium thread locker on the bolts specified in the manual. These are critical application bolts, you do not want them loosening off, and you don't want to be over-torquing bolts on the idler or tensioner pulley bearings.

As for the cam rotation, yes what you describe is 100% normal. Although the valves are closed using positive force by the rocker arms (desmodromic valve action) there is also a spring which keeps them closed when the cam lobe is not in contact with the rocker arm.

Every bearing should turn freely. If there's any doubt, replace it. Read through the previous posts in this thread, there is detailed info on how to determine a non-OEM replacement. Or... just order from Ducati, you will pay a premium but you'll also know you have the right part and it will save you a bunch of poking around trying to find someplace that sells the proper one. Sometimes Ducati parts are only marginally more expensive, sometimes they cost double or more. YMMV.
 

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Discussion Starter · #16 ·
I found out what ate away my belt. Somehow, a bolt made its way underneath the belt cover. Very weird, because no such bolt exists under the belt covers but the last time I took the covers off was about 1500km's ago, I figure if I myself had dropped it into there I would've known sooner.
Hence, the weird clunking sound from the horizontal cylinder..
 

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Glad you found that. Are you SURE it doesn’t belong in there ? Seems kind of strange a random homeless bolt found its way inside that cover. The covers aren’t deep and you have to move them around to fit them. I doubt I could put a bolt in the cover and manage to get it installed without the bolt falling out.
 

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That allen head fastener, sure looks like timing belt hardware to me.

Uli-
 

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Look for the "INNER" belt cover bolts, they are partially hidden by the cam pulleys and it is not uncommon to find them loose if no one has ever torqued them. All of them should be removed and red loctite coated. Nice you found the cause and even nicer that bolt did not do worse damage.
 

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Discussion Starter · #20 ·
The inner belt cover bolts underneath the pulleys are a size smaller and they're all there.
 
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