Belts Question (Again) (Sorry)M750

motomartin11 · 07-12-2020, 04:01 PM

Sorry I know there's been a lot said on this subject before. Before I bought my bike I gained a load of useful info from the PO who sent me pics of the cam belts which appeared nearly new. From looking at the history of my bike it doesn't appear to have done many miles at all-3000 miles according to the old MOT's since 2004!The dilemma for me is therefore this: as I don't know how old the belts are (even though they look almost new) or when they were last changed is it best for me to play safe and replace then to remove all doubt? If so do I do the job myself ? I'd say I'm a reasonably experienced owner /rider of many years(but little Ducati experience) and not fully confident to carry out a job which could completely wreck the engine if I get it wrong! I've had a look at some previous posts and Youtube guides-what I'm not clear on is do you actually have to lock the engine to change the belts or does it just have to be in the correct position as per the timing marks? Also I see that the pulleys can move after the belt tension is taken off / belts removed-does this matter as long as the timing marks are put back to the correct positions when fitting the new belts. I also see that there can be difficulty getting the pulley back in the exact correct position due to the effect of the desmodromic valve mechanism.Many thanks in anticpation.

Darkness · 07-12-2020, 04:36 PM

I’ve done it myself and found it to be easier than I expected. The hardest part was getting the belt covers off without scratching them.
Take plenty of photo’s before removing the belts to compare with the finished install before turning the engine over.
Having aligned the engine to the timing marks there should be no reason to rotate the engine until the new belts are on and tensioned. The cams like to turn a little once released from the belts, but provided you don’t force anything and just realign them when refitting the belt no harm is done.
You could damage things by winding the crank and the cams through a full turn, but you don’t need to, and why would you?
Whilst you have the belts off have a good look and feel of the idler and tensioner rollers. They do wear and have been known to fail, so check for smooth running and alignment. If replacing the tensioner roller be aware that some pattern items are not the right shape and misalign the belts.
There are a couple of methods of tensioning the belts. I used the 5mm & 6mm allen key method. See YouTube.
Refer back to your photo’s and turn the engine over by hand before firing up.
Simples!

Luddite · 07-12-2020, 05:09 PM

If you haven't come across these already, they give good step-by-step instructions on the procedure:

http://ducatisuite.org/beltchange.html
http://ducatisuite.org/belttension.html

http://www.ducatitoolrental.com/2-va...placement.html

Nickj · 07-12-2020, 07:31 PM

It is really easy to do the belts and as Darkness notes getting the covers off is probably the most difficult part of the job!!
There is a nice clear set of marks on the engine cases and the gear wheels to line up AND there are even some small removable screws on the belt casings that you can put longer screws through that will hold the cam pulleys in place.
Watch the DucatiTech videos a few times, take the belt covers off and have a look. If it looks too much bale out

Flip · 08-12-2020, 12:38 AM

As the others have said it is a relatively easy job to do at home if you are fairly spanner savvy.

I’ve never used any form of locking tool for the cam pulleys as they’re not under a huge amount of spring pressure but one will turn a tad out once you take the belt off but just re-set it when fitting the new one.

Once the new belts are on just double check the timing marks are lined up and the tensioner are tight.

I’ve found a long Allen socket best to use as it gives you better access to avoid chewing the hex up.

https://www.ebay.co.uk/itm/123667398244

If you’ve not got one already buy a Haynes manual as there’s clear instructions in there and I personally like their method (the old factory way) of tensioning using a spring balance.

Darkness · 08-12-2020, 07:09 AM

Something to bear in mind when considering changing belts is that because they are toothed, you are only choosing which tooth to put where so that the dots line up. The lining up isn’t exact, which is why photo’s of before and after to compare. One tooth out on the belt is quite a lot of rotation and is pretty obvious that it’s not in the right place!

utopia · 08-12-2020, 09:49 AM

The first time I changed my belts (also M750) I marked the position of the belt tensioners by drawing around the locking bolt heads with a sharpie pen.
It serves no real purpose but it does give a certain reassurance when the new belts are fitted and tensioned up, to see that the tensioners are in a similar position to how they were originally.

Also, if you are going to use the allen key method to set the tension, I would definitely recommend having a go on the old belts before you undo anything, to get a feel for how things should be (assuming the old ones are tensioned correctly, which they probably are).
Its very much a subjective method so its good to have a bit of practice first.

jerry · 08-12-2020, 10:28 AM

I used to do the old allen key method 5mm front 6mm rear but now I just do it by touch and feel ,, tried the Hz method but too fiddly , I guess Im just doing the spring tension method by experience .Main thing is to make sure the belt tension stays at the value u need when tightening up the adjusters

Dukedesmo · 08-12-2020, 10:45 AM

As above, on 2v engine's it's fairly easy. Good idea to take pics of the pulley positions as they may not be exactly on the lines but, one tooth out is a lot so shouldn't be tricky to get it right.

Once set, turn the motor over by hand several revolutions to steady everything and check there's no contact (and then check tension again) - I would strongly advise using an engine turning tool rather than the rear wheel/in gear as this doesn't give you any 'feel'.

With regards to tension, the allen key method is pretty good but is subjective and you maybe apprehensive if you're a belt 'virgin'! if in doubt err on the slightly loose side as they will tighten up when running hot and whilst they're unlikely to break through being tight, you may get accelerated bearing wear? - check the tensioner bearings for wear whilst you're in there.

This year, for the first time time I tried the frequency method using the Gates phone app and was pleasantly surprised at how easy and repeatable it was - I set the belts by conventional methods and then used the app to double-check and it was pretty much spot on, this on both the Monster and 916 so I'd definitely recommend it, along with your favoured method.

Good luck.

jerry · 08-12-2020, 01:13 PM

whats the frequency on a 2v engine using the gates app???

slob · 08-12-2020, 02:02 PM

Quote:

Originally Posted by jerry

whats the frequency on a 2v engine using the gates app???

For 1100evo: According to the service manual, the tension of new belts should be set to 140Hz and used belts should be 100Hz. The lower limit when the belts should be readjusted is given as 70Hz.
For 620/750ie: Horizontal 124Hz/Vertical 112Hz (+/- 5%)

Dukedesmo · 08-12-2020, 02:19 PM

Quote:

Originally Posted by jerry

whats the frequency on a 2v engine using the gates app???

According to CCW (whose belts I fitted) 99Hz and safe up to 110Hz (M900), not sure what Ducati state for their belts?

Luddite · 08-12-2020, 02:20 PM

Quote:

Originally Posted by slob

For 1100evo: According to the service manual, the tension of new belts should be set to 140Hz and used belts should be 100Hz. The lower limit when the belts should be readjusted is given as 70Hz.
For 620/750ie: Horizontal 124Hz/Vertical 112Hz (+/- 5%)

For the Evo, although the workshop manual says 140Hz, I think it's generally accepted that this is too tight and contributed to the "squeak" that some people experienced when the engine temperature rose to four bars and above. http://www.ukmonster.co.uk/monster/s...ad.php?t=48249

110Hz seems to be the new recommendation and I believe that Ducati North America issued a service bulletin to this effect, although I don't think there was any official change announced for the UK.

Note that, if you're using ExactFit belts, they recommend a tension of 99Hz with a maximum of 110Hz.

Blah blah · 08-12-2020, 05:19 PM

As has been said before, the hardest part is not scratching the covers !

I tried to use the frequency test on the last set (exact fit belts) I did but could never get anywhere near a consistent result, everywhere between 10 Hz and 200 hz (or there abouts, can't remember the actual figures but the difference was immense without physically changing anything) so I went back to the allen key method.

Make sure everything lines up before taking the old belts off perhaps even adding a bit of tippex on the marks to make them a bit clearer, and double check when they're back together. Also be prepared for one of the cams to move a little bit when you're trying to get the new belt on - scared the life out of me when it first happened, but just return it to where it was and try again.

manwithredbike · 08-12-2020, 09:55 PM

As per all above, a fairly easy job except getting the front cover off. A few tips i would add,
- Disconnect the battery before you remove belts
- If you haven't got a relatively new 6mm allen ket to loosen the tensioners, buy one and make sure it goes fully into the allen head before cracking them loose

And only one pulley will spring away from its timing mark from the valve spring, can't remember which but think it may be the front inlet??.

07-12-2020, 04:01 PM	#1
motomartin11 Registered User Join Date: Sep 2010 Location: stourbridge Bike: M750 Posts: 352	Belts Question (Again) (Sorry)M750 Sorry I know there's been a lot said on this subject before. Before I bought my bike I gained a load of useful info from the PO who sent me pics of the cam belts which appeared nearly new. From looking at the history of my bike it doesn't appear to have done many miles at all-3000 miles according to the old MOT's since 2004!The dilemma for me is therefore this: as I don't know how old the belts are (even though they look almost new) or when they were last changed is it best for me to play safe and replace then to remove all doubt? If so do I do the job myself ? I'd say I'm a reasonably experienced owner /rider of many years(but little Ducati experience) and not fully confident to carry out a job which could completely wreck the engine if I get it wrong! I've had a look at some previous posts and Youtube guides-what I'm not clear on is do you actually have to lock the engine to change the belts or does it just have to be in the correct position as per the timing marks? Also I see that the pulleys can move after the belt tension is taken off / belts removed-does this matter as long as the timing marks are put back to the correct positions when fitting the new belts. I also see that there can be difficulty getting the pulley back in the exact correct position due to the effect of the desmodromic valve mechanism.Many thanks in anticpation.

07-12-2020, 04:36 PM	#2
Darkness . Join Date: May 2007 Location: Stockbridge Bike: M900 Posts: 1,984	I’ve done it myself and found it to be easier than I expected. The hardest part was getting the belt covers off without scratching them. Take plenty of photo’s before removing the belts to compare with the finished install before turning the engine over. Having aligned the engine to the timing marks there should be no reason to rotate the engine until the new belts are on and tensioned. The cams like to turn a little once released from the belts, but provided you don’t force anything and just realign them when refitting the belt no harm is done. You could damage things by winding the crank and the cams through a full turn, but you don’t need to, and why would you? Whilst you have the belts off have a good look and feel of the idler and tensioner rollers. They do wear and have been known to fail, so check for smooth running and alignment. If replacing the tensioner roller be aware that some pattern items are not the right shape and misalign the belts. There are a couple of methods of tensioning the belts. I used the 5mm & 6mm allen key method. See YouTube. Refer back to your photo’s and turn the engine over by hand before firing up. Simples! __________________ Original and Best since 1993

07-12-2020, 07:31 PM	#4
Nickj Too much time on my hands member Join Date: Jun 2007 Location: Forest Of Dean Bike: S2r Posts: 3,189	It is really easy to do the belts and as Darkness notes getting the covers off is probably the most difficult part of the job!! There is a nice clear set of marks on the engine cases and the gear wheels to line up AND there are even some small removable screws on the belt casings that you can put longer screws through that will hold the cam pulleys in place. Watch the DucatiTech videos a few times, take the belt covers off and have a look. If it looks too much bale out __________________ "The final measure of any rider's skill is the inverse ratio of his preferred Traveling Speed to the number of bad scars on his body." Song of the sausage creature

08-12-2020, 12:38 AM	#5
Flip Registered User Join Date: Mar 2010 Location: Beachtown Bike: M900 Posts: 2,188	As the others have said it is a relatively easy job to do at home if you are fairly spanner savvy. I’ve never used any form of locking tool for the cam pulleys as they’re not under a huge amount of spring pressure but one will turn a tad out once you take the belt off but just re-set it when fitting the new one. Once the new belts are on just double check the timing marks are lined up and the tensioner are tight. I’ve found a long Allen socket best to use as it gives you better access to avoid chewing the hex up. https://www.ebay.co.uk/itm/123667398244 If you’ve not got one already buy a Haynes manual as there’s clear instructions in there and I personally like their method (the old factory way) of tensioning using a spring balance. __________________ You're perfect, yes, it's true- But without me you're only you!

08-12-2020, 07:09 AM	#6
Darkness . Join Date: May 2007 Location: Stockbridge Bike: M900 Posts: 1,984	Something to bear in mind when considering changing belts is that because they are toothed, you are only choosing which tooth to put where so that the dots line up. The lining up isn’t exact, which is why photo’s of before and after to compare. One tooth out on the belt is quite a lot of rotation and is pretty obvious that it’s not in the right place! __________________ Original and Best since 1993

07-12-2020, 05:09 PM	#3
Luddite Registered User Join Date: Aug 2011 Location: Southampton Bike: M1100evo Posts: 2,465	If you haven't come across these already, they give good step-by-step instructions on the procedure: http://ducatisuite.org/beltchange.html http://ducatisuite.org/belttension.html http://www.ducatitoolrental.com/2-va...placement.html

08-12-2020, 09:49 AM	#7
utopia No turn left unstoned Join Date: Jun 2010 Location: leicester Bike: M750 Posts: 4,545	The first time I changed my belts (also M750) I marked the position of the belt tensioners by drawing around the locking bolt heads with a sharpie pen. It serves no real purpose but it does give a certain reassurance when the new belts are fitted and tensioned up, to see that the tensioners are in a similar position to how they were originally. Also, if you are going to use the allen key method to set the tension, I would definitely recommend having a go on the old belts before you undo anything, to get a feel for how things should be (assuming the old ones are tensioned correctly, which they probably are). Its very much a subjective method so its good to have a bit of practice first.

08-12-2020, 10:28 AM	#8
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,816	I used to do the old allen key method 5mm front 6mm rear but now I just do it by touch and feel ,, tried the Hz method but too fiddly , I guess Im just doing the spring tension method by experience .Main thing is to make sure the belt tension stays at the value u need when tightening up the adjusters __________________ MONSTERMAN

08-12-2020, 10:45 AM	#9
Dukedesmo Registered User Join Date: Sep 2010 Location: Leics Bike: M900 Posts: 2,842	As above, on 2v engine's it's fairly easy. Good idea to take pics of the pulley positions as they may not be exactly on the lines but, one tooth out is a lot so shouldn't be tricky to get it right. Once set, turn the motor over by hand several revolutions to steady everything and check there's no contact (and then check tension again) - I would strongly advise using an engine turning tool rather than the rear wheel/in gear as this doesn't give you any 'feel'. With regards to tension, the allen key method is pretty good but is subjective and you maybe apprehensive if you're a belt 'virgin'! if in doubt err on the slightly loose side as they will tighten up when running hot and whilst they're unlikely to break through being tight, you may get accelerated bearing wear? - check the tensioner bearings for wear whilst you're in there. This year, for the first time time I tried the frequency method using the Gates phone app and was pleasantly surprised at how easy and repeatable it was - I set the belts by conventional methods and then used the app to double-check and it was pretty much spot on, this on both the Monster and 916 so I'd definitely recommend it, along with your favoured method. Good luck. __________________ M900, 916, LeMans II.

08-12-2020, 01:13 PM	#10
jerry Old Git Join Date: May 2006 Location: Cricklade Bike: Multiple Monsters Posts: 2,816	whats the frequency on a 2v engine using the gates app??? __________________ MONSTERMAN

08-12-2020, 05:19 PM	#14
Blah blah Upsetting normal people.. Join Date: Mar 2007 Location: Portreath Bike: S2r Posts: 833	As has been said before, the hardest part is not scratching the covers ! I tried to use the frequency test on the last set (exact fit belts) I did but could never get anywhere near a consistent result, everywhere between 10 Hz and 200 hz (or there abouts, can't remember the actual figures but the difference was immense without physically changing anything) so I went back to the allen key method. Make sure everything lines up before taking the old belts off perhaps even adding a bit of tippex on the marks to make them a bit clearer, and double check when they're back together. Also be prepared for one of the cams to move a little bit when you're trying to get the new belt on - scared the life out of me when it first happened, but just return it to where it was and try again. __________________ Power is nothing without control... I have neither ! Last edited by Blah blah; 08-12-2020 at 05:24 PM..

08-12-2020, 09:55 PM	#15
manwithredbike aka Phil Join Date: Nov 2005 Location: derry Bike: M900 Posts: 376	As per all above, a fairly easy job except getting the front cover off. A few tips i would add, - Disconnect the battery before you remove belts - If you haven't got a relatively new 6mm allen ket to loosen the tensioners, buy one and make sure it goes fully into the allen head before cracking them loose And only one pulley will spring away from its timing mark from the valve spring, can't remember which but think it may be the front inlet??. __________________ .. ~