Quote from: EEL on October 20, 2008, 10:16:36 PM
And THATS the problem. "Supposedly"...Its tried and true method for almost 10 years. I'd hate to throw out a method based on supposition. If anyone has any concrete proof, please speak up.

The problem with not setting the proper tension on any Ducati motor is the belt tension effects cam timing. There is no accurate enough method (in my opinion) without using the proper tool.

Why not do everything and bring the bike to the dealer so they can check the tension. If you've got it all ready to go it will only take 15-20 minuets to check tension and adjust properly. What is that $30? For that small amount of money I'd sure feel more comfortable for my own bikes - luckily I have access to the DDS!

Quote from: desmoworks on October 21, 2008, 03:00:46 PM
The problem with not setting the proper tension on any Ducati motor is the belt tension effects cam timing. There is no accurate enough method (in my opinion) without using the proper tool.

Why not do everything and bring the bike to the dealer so they can check the tension. If you've got it all ready to go it will only take 15-20 minuets to check tension and adjust properly. What is that $30? For that small amount of money I'd sure feel more comfortable for my own bikes - luckily I have access to the DDS!

thats all right if a dealer close , why dont you do us all a favor and adjust your belts too the right tension then see what size allen key fits

I had the tension set by the dealer on my S2R1k a few months ago.  They used the harmonic device to set the tension for ~115 Hz.  A few weeks later I opened it up to see how it measured mechanically.  Could not fit a 5mm wrench, didn't bother to see how small the clearance was, but I'm guessing about 2 or 3 mm.  The 45* twist was real close to right on, I would say that I could twist the belt a little more than 45*.  I did the twist on both of the long runs between the idlers and the cam pulley, there was very little difference in terms of how much I could twist the belt.  Going forward, I will also be using the 45* twist method.

Quote from: desmoworks on October 21, 2008, 03:00:46 PM
Why not do everything and bring the bike to the dealer so they can check the tension. If you've got it all ready to go it will only take 15-20 minuets to check tension and adjust properly. What is that $30? For that small amount of money I'd sure feel more comfortable for my own bikes - luckily I have access to the DDS!

The engine must be cold.  That means leaving the bike overnight, which can be a PITA.

Quote from: desmoworks on October 21, 2008, 03:00:46 PM
The problem with not setting the proper tension on any Ducati motor is the belt tension effects cam timing. There is no accurate enough method (in my opinion) without using the proper tool.

I was discussing this with someone the other day.  This may be wrong, lets just say I'm thinking out loud.....

It seems that the correct way to tension the belt is to lock the cam and crank into position, and then loosen the bolts that allow the cam pulley to rotate independently of the cam (like one would do to degree the cams).  Set the tension, then retighten the bolts that couple the pulley to cam.  This allows the tension to be set evenly on both sides of the cam pulley.  If the pulley is not loosened prior to tensioning the belt, there will be some potential for the timing to change a little bit, because the tensioner will be trying to pull the belt tight on only one-half of the run (the run between the main pulley and one side of the cam pulley).

Does this make sense?

I swapped my S4 belts by lining up the timing marks, using the cam wheel spacer, and gauging with 5 mm allen key and the proverbial twist. I was a bit freaked out about it but my worries waned after riding and forgetting about it. 2k miles later I'm cool. Don't err on the side of too tight tho. Use LT Snyders' guide, shop manual, and Chris Kellys' index as a resource.

Quote from: Ivan on October 22, 2008, 12:35:25 PM
I was discussing this with someone the other day.  This may be wrong, lets just say I'm thinking out loud.....

It seems that the correct way to tension the belt is to lock the cam and crank into position, and then loosen the bolts that allow the cam pulley to rotate independently of the cam (like one would do to degree the cams).  Set the tension, then retighten the bolts that couple the pulley to cam.  This allows the tension to be set evenly on both sides of the cam pulley.  If the pulley is not loosened prior to tensioning the belt, there will be some potential for the timing to change a little bit, because the tensioner will be trying to pull the belt tight on only one-half of the run (the run between the main pulley and one side of the cam pulley).

Does this make sense?

That is exactly how it is done on ths 1000ds engine - the crank is set for comp on horizontal cyl and then both cams are locked by passing a 6mm dia bar through left side cam covers. Both belts can then be tensioned at this setting.
It IS a diy job and no need to take it to any dealer.

Quote from: Jethro on October 22, 2008, 04:34:16 PM
That is exactly how it is done on ths 1000ds engine - the crank is set for comp on horizontal cyl and then both cams are locked by passing a 6mm dia bar through left side cam covers. Both belts can then be tensioned at this setting.
It IS a diy job and no need to take it to any dealer.

Thanks Jethro....Do you rely on the 6mm bar to hold the pulleys while you tighten/loosen the bolts that couple the pulley to the cam?  Not having looked at the torque specs for the bolts that hold the pulleys to the cams, I have visions of the locking pins breaking-off inside the cams.

Ivan, here are a few pics to show things better. You set the crank at tdc compression for H cyl and lock both cams by removing blanking screws from left side cover plates and locating 6mm bar into locating slot in camshaft.

Don't forget a bit of rag over spark plug hole or you could drop the coper washer in it.


Here is a pic with left side cover removed to show the locating slot.


Here is a pic showing how the 6mm bar locks the camshaft - set up with cover removed just to show the location but obviously you don't need to remove the cover. You leave the 6mm bar in place until you have tightened the three screws that lock the pulley.
If  you find a tightening torque for these screws then please post it because it isn't in my manual. So there it is - and you will maintain valve timing whatever method you use for belt tension. Another point is that although the V cyl isn't at TDC comp, the closing springs will not alter belt tension because the camshaft is locked so you can set both belts with this one crank setting.

You will always maintain timing unless you move a tooth.  A loose belt will allow the timing to vary.

For anyone using a manual be aware that there is a spec (say 140Hz) to tighten the belts to while the crank and cams are locked with the tools. Then there is an operating spec that you back the belt tension down to (often around 80 for Ducati models, but it varies). When you take the locking tools off and loosen the belts up to the correct tension that is when you achieve correct timing.

Quote from: desmoworks on October 23, 2008, 10:00:36 AM
For anyone using a manual be aware that there is a spec (say 140Hz) to tighten the belts to while the crank and cams are locked with the tools. Then there is an operating spec that you back the belt tension down to (often around 80 for Ducati models, but it varies). When you take the locking tools off and loosen the belts up to the correct tension that is when you achieve correct timing.

That's not how to do it according to the Ducati workshop manual.

Quote from: Jethro on October 23, 2008, 10:08:58 AM
That's not how to do it according to the Ducati workshop manual.

That's what I'm saying. I'm at the Ducati training right now (I'm on lunch break). We just went through this yesterday. The manual tells how to set them with the tools installed, but there is a service bulletin on the correct Hz after the tools are removed. Ducati has charts (for dealers) that show the correct Hz wtih tools installed and uninstalled.

This is why it is a good idea to have a dealer do it... home mechanics aren't privy to all the info. They don't get service bulletins. There have probably been 10 bulletins on the new monster 696 already. There is a lot of info that comes out that isn't in the original service manual. They make the manual and don't revise and re-send it every time there is something new.

The point about the belt have an installation and operating tension is no secret. I hope you aren't running around with your belts at 140Hz and hope you haven't told others to do that?

Quote from: desmoworks on October 23, 2008, 10:15:24 AM
I hope you aren't running around with your belts at 140Hz and hope you haven't told others to do that?

Thanks for info and I haven't told anyone to use the Hz method to set their belts nor have I used that method myself. What I have said is that I fitted new belts 13,000 miles ago using the 45ˆ twist  method and it works for me. Before the 1000ds engine was introduced, thousands of guys set their belts using the allen key method and that worked for them. I am not impressed with the Hz method as Ducati don't appear to be able to make up their mind on the correct tension.
I am a bit more than a home mechanic - I am an engineer and have worked on engine design for 40 years. Belt tension is not that critical - it can be too tight or too loose but there is a range of tensions that work ok. During service the belt tension changes anyway but that is nothing to get alarmed about - although Ducati perhaps tell you there is.
I am quite happy to run my belts for another few thousand miles and will change them in the winter - also using the 45ˆ twist method.

Setting the belts with the Ducati tools to the specified spec then loosening to operating spec once tools are removed produce a very reliable result. Bruce verified it with a degree wheel on the 1000DS motor.

The Ducati spec allows +/- 5Hz so there is no perfect number. Like anything on a motor there is a tolerance it has to be in, but the "tension on assembly" and "tension after service" as Ducati refers to them are always farther apart than the acceptable range for one or the other.

For those without a dealer near or who just like to tinker it is definitely possible to use a laptop with quality microphone and tuning program to set tension at home... that would produce a reliable result unlike twisting belts and other methods where there is no actual measurable output. You measure roughly half way between the lay shaft pulley and the belt tensioner. Ducati has a tool to mount the measuring module for the DDS, but it will only work with the DDS. You will get a different readout by measuring different parts of the belt.