View Full Version : Monster 696 timing belts not aligned with the cam pulley
Hello guys, i just did my first belt and tensioner change( Monster 696) and after i mounted all the parts and tensioned the belts (5 and 6 mm allen key method) , I started the engine. The engine started normaly, the sound was normal but I noticed that the belts are crossing the edge of the cam pulley. I stopped the engine , pushed the belt in place and started again. After start, the belt was in the same position as before... its not aligned with the pulley. I noticed that the cam pulley(both vertical and horizontal) have some freeplay back and forth. Is this normal, could this be the issue? I attached some photos with the issue. Im looking forward to receive some advices. Thank you very much and sorry for my english :D
https://ibb.co/KxTTs0R
https://ibb.co/my6Y0TJ
https://ibb.co/7yDm9XK
https://ibb.co/n65MJcS
Hi Alex
you definitely have something wrong there, you’d find the belts and covers in contact.
Check the if any of the four tensioner rollers feel notchy, bearing failures in the tensioners are fairly common and will cause them to run out of line.
A little side play in the top belt pulleys is normal.
Hi slob , yep something is wrong there , all 4 belt tensioners and belts are new and i think they are OEM too.... im going to compare the new belts with the old belts and tensioners too so see if they match :(
Luddite
30-04-2020, 08:09 PM
A little side play in the top belt pulleys is normal.
slob's right about the side play in the cam pulleys, but the play is eliminated once the motor is running.
Unlike the old motors, the cams in the 696/796/1100 run directly in the heads without separate bearings. They float on a film of pressurised oil when the engine is running. So, when the engine is off, you can pull the camshafts in and out a small amount but, with the engine running and with full oil pressure, the oil pushes the camshaft across towards the belt side until it runs against the thrust surface.
https://i.postimg.cc/90hqGFs1/Photo-Note-ncr3000003-ncr-ducati-2v-cams-1-2-2755.jpg (https://postimages.org/)
ty for explanation , i just need to figure out if my belts are what they need to be and why the are not running on the pulley surface
Update : the problem were the faulty mobile tensioners bought from eBay. In the pictures, left side is the new tensioner, right side the old OEM tensioner. Notice the distance between the roller bearing and the metal part. Do you think im entitled to get refound for these tensioners? They were of course mounted on the bike. Thanks for helping me guys.
https://ibb.co/zGRR60Q
https://ibb.co/Vq4w7wr
https://ibb.co/H431Bfc
Darren69
02-05-2020, 06:30 AM
If you paid with paypal you'll be covered and should get a refund np.
The Clockie
02-05-2020, 07:21 AM
This is just guesswork, but the run of the belts should depend on the alignment of the toothed pulleys, not the tensioners. The tensioners are smooth, and I'd expect the width comfortably covers the belts, so a slight difference in the support pivot length shouldn't make a difference to where the belts run on the toothed pulleys.
Not so?
Nick
after i swapped the new tensioners with the old ones , the problem dissapeared so they are big difference. They were pushing the belt to exterior of the toothed pulleys...
Mr Gazza
02-05-2020, 07:52 AM
I agree with Nick, the position of the roller on the belt cannot effect the tracking of it.
But if it is out of square with the belt then it will make it run off. I witness this when I use support rollers on long lengths of wood when I run it over machines. If the (smooth) roller is not dead square to the wood, it will run it off course, quite uncontrollably.
To test this you could bolt or screw the tensioner(s) to a flat piece of wood or metal and check the rollers with an engineers square.
If the rollers are running the belts off why do they not continue to ride off the pullies? Or have you not run the engine (long enough) with these tensioners?
Well guys, the bike run only 10 minutes on idle and I've stopped it because I did not liked at all the position of the belts. From what I could see the belts stopped from moving in the position you can see in the pictures. Good ideea to measure them with an engineer square
Mr Gazza
02-05-2020, 09:23 AM
I'm glad you are a sensible chap and stopped the engine when you noticed the fault. I don't think I always run it up after a belt change with the covers off, but I will make a point of it from now on, besides I like seeing the patches of white lettering whizz round in opposite directions.. :D
Both belts appear to have run off the same amount, so it would point to a consistent manufacturing fault in the tensioners, I bet it's not very much though.
utopia
02-05-2020, 11:12 AM
This may be a complete red herring .. in fact it almost certainly is, but ....
It is/was fairly common practice to machine plain rollers for flat drive belts with a crowned surface, ie a bit fatter in the centre.
As far as I'm aware, this is done so that the belt will self-centralise on the roller.
I believe this was the norm in old machine shops and mills where many machines were flat-belt driven from a common shaft.
Like I said, its very likely a red herring and probably doesn't apply to the monster tensioner rollers which I strongly suspect are machined parallel ... but it would be interesting to measure them.
manwithredbike
02-05-2020, 11:18 AM
The drive pulleys have edges so i'd guess the belts couldn't run right off. But if the tensioner pulleys were not square on, they could drive them off the cam pulleys to a degree, and there'd def be friction there, prob causing faster wear on the belts -- depending on how much the tensioners were off kilter.
can you post a photo of your drive pulleys?
here are the only pics i had in my phone
https://ibb.co/P4Rkzpf
https://ibb.co/kxkTWLy
manwithredbike
03-05-2020, 05:53 PM
Looks like there's a bit of excessive wear on the outer edge of that belt ok. Likely coming from the edge of the drive pulley, suggesting that the belt is indeed not running onto/off it true.
Presumably your oil level is ok and the oil warning light goes out instantly when you start the engine?
just a little wear youre right from the edge of the drive pulley, but they only run only run for like 5- 10 minutes its not much wear at all , do you sugest not to use these belts? they are new..
manwithredbike
03-05-2020, 09:14 PM
just a little wear youre right from the edge of the drive pulley, but they only run only run for like 5- 10 minutes its not much wear at all , do you sugest not to use these belts? they are new..
I wouldn't worry about using them, i'm sure they're fine, but i'd want to see them running true and straight whatever the cause. You can imagine if the edge has been worn like that in 10 mins, they would soon deteriorate with full-on use.
I once had the outer lip (press fit ring) come off the outer drive pulley, coupled with a tensioner bearing failure (possible cause) the end result was the outer 10% of the belt shredding itself while eating half way through the horizontal belt cover. ‘02 M620ie.
Oil pressure is good, so assume top pulleys are lined up with engine running, most likely suspect at this point is non-OEM (eBay) tensioners.
I wouldn't worry about using them, i'm sure they're fine, but i'd want to see them running true and straight whatever the cause. You can imagine if the edge has been worn like that in 10 mins, they would soon deteriorate with full-on use.
The problem was the aftermarket mobile tensioners, you can see some photos in this thread, i will refund them and buy OEM,
manwithredbike
04-05-2020, 03:05 PM
Good to know this for future reference - about spurious tensioners. And, it's always wise to check new belts/tensioners etc shortly after fitting.
Would be good to hear an update when you get sorted with new tension pulleys. Were you able to check the suspect pulleys to see how badly (or not) they were off?
Darren69
04-05-2020, 03:19 PM
yea, and where they came from?
Good to know this for future reference - about spurious tensioners. And, it's always wise to check new belts/tensioners etc shortly after fitting.
Would be good to hear an update when you get sorted with new tension pulleys. Were you able to check the suspect pulleys to see how badly (or not) they were off?
unfortunately not , i dont have a engineer square and i already sent them back for refund
yea, and where they came from?
From a local producer in Italy. He said that these tensioners are more robust than OEM and have 3 years guarantee but too bad that didnt fit...
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