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Thanks for that Majorsoftie,

Yeh, gotta do that Martin Brickwood collet mod, is that just a"drop in" mod...like I don't have to have a musical ear to do it!:p
 

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Well tonight I went out and checked the belts on my PS....now at about 3700 miles and 2 years from manufacture. The vertical passed an 8mm allen and the horizontal a 5mm. The rollers were clean and spinning easily. The belts looked good except for slight wear showing on the edges where they rub against the lip on the driving pulley. I'll put new Ducati belts on it and at 6000 miles check the valves. I have shim kits for both the old 2-valve and the new one (which takes standard 4-valve diameter shims.) I got both kits from EMS. The 900SS has MBP collets and are highly recommended, if for no other reason than they're easier to install then the tiny split ring collets from OEM. I'll prolly set the belts at 4mm/45 degree twist as recommended by LT unless you guys with the tonal tappers tell me otherwise. I have both of LT's maintenance manuals btw. Great reading and very useful. Good discussion....thanks.
 

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first....I didn't mention in my last post that I had already figured out my erroneous readings were caused totally by my errors! I am glad I didn't change anything!

next....good news! I dumped winscope...and got the other one (not the Chromatia?)...anyway much easier. BTW, winscope probably works fine, I just couldn't figure out what I was doing wrong.

YellowDuck, you were right, the readings you get are either right or wrong, I was able to pluck my belts and obtain readings of 136.1 and 136.4 repeatedly.

I am totally satisfied and I am leaving mine alone....I will check them again with the next oil change....it's so easy once I figured out what I was doing to mess it up!

Thanks Again !!!

On to suspension and tires....gotta get ready for LVMS.

That's great news. Really glad you got it sorted.
 

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Help.

Can somebody who has set the belts by Hz (110hz-140hz) please go and run a allen under the belt by the roller and see which one its supposed to be and then repport how tight.

That would help many includeing me.
 

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Just FYI, and this has been covered here, 140 is way too tight - it was a mistake in the manual. 110 Hz is the correct setting. I think 105 to 115 is the tolerance.

I'd measure them with allen keys if I was at home at the moment, but I'm not. Hopefully someone else can do that for you. Although, I seem to remember a pretty good argument about how that really wasn't recommended with the DS1000....
 

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Im gonna do it by Hz but it would be nice to get a ruff estimate if the Hz metod is way wrong then you can double check with the allen key.
 

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Hard to believe the 5-6mm allen deal worked for so long on the 900 and suddenly is taboo for the DS. What really changed? There are still the same number of pulleys correct? A similar distance apart, spinning at a similar velocity. It's a mechanical system with a certain realistic tolerance I'm sure.
My bike needs belts because of age not millage. I can stick a 7mm in the vertical and maybe a 1mm in the horizontal but it runs fine. No sign of rubbing inside the covers so 7mm must not be dangerously loose. I think the 1mm is too tight personally and will go with 3mm H, and 4mm V when I replace. I'm not racing so it won't see prolonged high RPM. You need the belts to handle the heat expansion yet not jump a tooth, that's it, no rocket science.
 

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You need the belts to handle the heat expansion yet not jump a tooth, that's it, no rocket science.
You are mistaken. The tighter and much more narrow specification will result in more perfectly controlled valve timing.

There are two obvious possible reasons for the change to the much tighter spec.:

1. The more carefully controlled valve timing results in more carefully controlled emissions (I consider this very likely).

2. The more carefully controlled valve timing is necessary to prevent valve contact with the current cam/valve timing (possible, but my money's on #1).
 

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When I replaced the belts on PS I noticed that they are wider, and presumably stronger. Talking to the mechanics at my dealer, they said they set harmonic specs at two levels. 110 if the belt is new and 75 if it's not.
FWIW.
 

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You are mistaken. The tighter and much more narrow specification will result in more perfectly controlled valve timing.

There are two obvious possible reasons for the change to the much tighter spec.:

1. The more carefully controlled valve timing results in more carefully controlled emissions (I consider this very likely).

2. The more carefully controlled valve timing is necessary to prevent valve contact with the current cam/valve timing (possible, but my money's on #1).
If you have any data to back up #1 I'd love to see it.

As for #2, maybe you took me too literally with "jumping a tooth". That would likely be pretty loose, but I'm presently at 7mm on the vertical with no issues and I'm sure others have run looser without catastrophe.
 

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If you have any data to back up #1 I'd love to see it.
A loose belt does not maintain as precise a relationship between the drive and driven pulleys. This is due both to changes in the relationship during acceleration, decceleration, and maintained rpm, as well as the impact of "centrifugal force" on the belt (the quotations reflect my acknowledgment that "centrifugal force" is a term that is commonly understood but a bastardization of the the forces involved as defined by modern Physics). I considered that to be self-evident. If you do not understand the mechanics involved which would create this result, I am sorry.

Modern emission controls require more precise control of all aspects of the engine's cycles. This is why engine makers have gone to electronic ignitions, fuel injection, and ECU's. The change to these more precise systems for improved emissions control is very well documented. Thus my speculation that the more precise control provided by the tighter belt may be intended to contribute to the needs of meeting emissions.

As for #2, maybe you took me too literally with "jumping a tooth". That would likely be pretty loose, but I'm presently at 7mm on the vertical with no issues and I'm sure others have run looser without catastrophe.
No, I did not take you too literally. You appear to have misunderstood my post, as that is unrelated to my point. More radical valve timing and greater overlap can require more precise valve timing control to avoid contact.

As I said, I doubt the DS motor has radical enough valve timing for this to be an important factor, and I find it much more likely that the tightened and narrowed spec is emissions related.





Your point, if I understood it correctly, was that all that matters is that the tension is low enough to prevent bearing damage and high enough to prevent jumping a tooth on the pulley: that there is no difference that would impact engine performance as long as the tension falls anywhere between these two danger points.

My point was that this is incorrect.
 

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I'm certan that the new spec for the belts was to do with the emissions. If the valve timing varied from one cylinder to the other, this would obviously spoil the engine's efficiency and thus produce more unburnt hydrocarbons.
 

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Your point, if I understood it correctly, was that all that matters is that the tension is low enough to prevent bearing damage and high enough to prevent jumping a tooth on the pulley: that there is no difference that would impact engine performance as long as the tension falls anywhere between these two danger points.

My point was that this is incorrect.
I don't recall saying that it would be perfect, that was sort of my point. It doesn't need to be spot on to run well. A small change in emissions doesn't really concern me. I have removed the cat and unplugged the O2 also. If you are running a completely stock bike and set your belts to 110hz exactly just to be eco-friendly that is admirable.
I stated what was "needed" not what was perfect. Not sure how I was incorrect. The belts don't "need" to be at 110hz to work, even to work well.
 

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MajorSoftie suggested
There are two obvious possible reasons for the change to the much tighter spec.:

1. The more carefully controlled valve timing results in more carefully controlled emissions (I consider this very likely).

2. The more carefully controlled valve timing is necessary to prevent valve contact with the current cam/valve timing (possible, but my money's on #1).
Perhaps reason #3 is the real reason - extracting more $ from Ducati owners who are too baffled by bullshit to attempt what is really a simple maintenance task themselves?
 

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Perhaps reason #3 is the real reason - extracting more $ from Ducati owners who are too baffled by bullshit to attempt what is really a simple maintenance task themselves?
Well, I think that's always an overriding factor in all of these decisions. ;)
 

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The main problem is not the need for a very specific belt tension, whatever the reason for that really is, but a reliable and inexpensive means of the average DIY Ducati owner achieving a consistent 110Hz. Some forum members have reported success with various software packages or guitar tuners. Most of those methods seem a bit fiddly and inconsistent, but the twist method, and a modified allen key method, also seem a little crude and inexact. :crazy:

The US$250 Harmonic Cam Belt Tensioning Tool sold by Desmo Times may end up being my best option, and would quickly pay for itself. All of the tools and parts that I've bought so far (shim kit, VDST, digital micrometer etc. etc.) have cost less than one major service, so another $250 is no big deal in that context. Still, a cheaper - but still reliable - method would be nice.... ;)
 

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Well, I was able to do it simply with a tone generator and listening to the belt. This cost nothing, as there are free tone generator programs available.

The difference between 110 Hz and 103 Hz or 117 Hz is two side-by-side notes on the piano, so it is VERY easy to get the tension to spec, and, in fact, get it within a couple Hz, if one has any sense of musical notes.

My hearing has had 10 years of tending bar in a nightclub and 35 years of motorcycle riding, and I can hear it. It simply isn't that hard.
 
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