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cam belt break in?

4.7K views 24 replies 13 participants last post by  Langanobob  
#1 ·
I just put on my first set of cam belts today and need to know after how many miles should I recheck the tension? Also the bike is a 96 M900 14,003 miles, I didn't know how old the belts were so I replaced them.
 
#2 ·
I have a 96 and I don't re-tension belts.

Run them for a couple or three years and replace them.
 
#3 ·
You should check belt tension at least every 6K, for a regular use bike and every 3K for a heavy/aggressive use bike (i.e. frequent track, or race use).

The belts should be set at 110Hz cold using the DDS. There is no reliable "dirty trick" method of setting tension, so just have it done correctly at your local dealer.

Unless you want to shell out $5K for the device, and then convince Ducati to sell you one, it's cheaper, and easier in the long run to just have the dealer do it.

And I know it looks cool and all, but don't run w/o out belt covers!! It'll be that "one in a million" piece of debris that lodges in your belts and trashes it all. I've seen it happen.

Older model Ducs, with less than 12K on them should have the belts replaced ASAP! Prior to 1998, the belts were not kevlar re-inforced (white printing). They were prone to failure just by talking about them. If you have any doubts, replace them with the newer version belts (red printing).

$120 for new belts, or $2000+ for a rebuild (parts+labor+machining costs, etc.). Which would you rather pay?
 
#4 ·
duckwrench13 said:
You should check belt tension at least every 6K, for a regular use bike and every 3K for a heavy/aggressive use bike (i.e. frequent track, or race use).

The belts should be set at 110Hz cold using the DDS. There is no reliable "dirty trick" method of setting tension, so just have it done correctly at your local dealer.

Unless you want to shell out $5K for the device, and then convince Ducati to sell you one, it's cheaper, and easier in the long run to just have the dealer do it.

And I know it looks cool and all, but don't run w/o out belt covers!! It'll be that "one in a million" piece of debris that lodges in your belts and trashes it all. I've seen it happen.

Older model Ducs, with less than 12K on them should have the belts replaced ASAP! Prior to 1998, the belts were not kevlar re-inforced (white printing). They were prone to failure just by talking about them. If you have any doubts, replace them with the newer version belts (red printing).

$120 for new belts, or $2000+ for a rebuild (parts+labor+machining costs, etc.). Which would you rather pay?
I should?

Do I have to?
 
#6 ·
One belt change back I used the DDS for my belts. When I was done, son of a gun, a 5mm allen fit, 4 was loose and a six was too tight. As far as the dual spark and newer 4 valvers go I have never seen a reliable alternative, though I am sure time will fix that.

There are reliable alternative to the DDS though: http://www.gates.com/brochure.cfm?brochure=2787&location_id=3539
is one example. Chris Kelley once posted a computer program (free) that, combined with a laptop and a microphone should work.
 
#8 ·
duckwrench13 said:
The belts should be set at 110Hz cold using the DDS. There is no reliable "dirty trick" method of setting tension, so just have it done correctly at your local dealer.
How many dealers even own a DDS? Here's the trusted DML sponser CA Cycleworks using the allen wrench "trick" :eek:
http://www.ca-cycleworks.com/videos/
 
#10 ·
Ive been using the allen wrench method for about 13 years now, we had a discussion on the 851/888 list about this and one of the more respected members was quoted in there as saying,

Here's Bruce's comments

The specs given are way to tight. They have been
revised 3 times already. Lots of idler bearing
failures. Looser is better than tight.

The way I tought you 4MM play between the pulleys at
TDC or 45 degrees twist on the longest run at
tdc is the best way.

The new specs are something like 70 to 80 hz 2 valve
and 90 to 110 4 valve. This works out to 45
degree twist every time.
Heres the specs that were in question

> > The settings are from the ducati wall charts (the vertical is
> always
> > the lowest number (loosest):
> >
> > Horiz. Vert.
> > 400/600/620/750 124 Hz 112 Hz
> >
> > 800 160 Hz 145 Hz
> >
> > 900/St2 146 Hz 121 Hz
> >
> > 1000 2/3Valves 142 Hz 142 Hz
> >
> > All 4Valves 110 Hz 110 Hz
> >
> > 748R 98 Hz 98 Hz
 
#11 ·
ducman851 said:
Ive been using the allen wrench method for about 13 years now, we had a discussion on the 851/888 list about this and one of the more respected members was quoted in there as saying,

Heres the specs that were in question

> > The settings are from the ducati wall charts (the vertical is
> always
> > the lowest number (loosest):
> >
> > Horiz. Vert.
> > 400/600/620/750 124 Hz 112 Hz
> >
> > 800 160 Hz 145 Hz
> >
> > 900/St2 146 Hz 121 Hz
> >
> > 1000 2/3Valves 142 Hz 142 Hz
> >
> > All 4Valves 110 Hz 110 Hz
> >
> > 748R 98 Hz 98 Hz
I always believe Bruce. [thumbsup]
 
#12 ·
When I said there was no "dirty trick," I was not implying that the allen wrench method was wrong, merely trying to discourage a lesser mechanically inclined/experienced owner from trying something they were not entirely familiar with, or completely understood the process.

I have used the 5mm trick when I have had no other alternatives. For those of us that have the mechanical knowledge, and the experience, then yes, it can be done with a fair amount of reliability. I would still recommend that you at least have the belts checked by a local dealer. Better safe than sorry.

I know that all of us turn to these tech threads for advice, guidance, and to save a few dollars. But, please, in all seriousness, if you do not know what you are doing to start with, then anything you read off of any boards will not do you any good. Do not risk doing more harm than good, just in the name of saying a few bucks.

If you have a reliable, Ducati experienced mechanic near by, then drop by and see if they can help you out. If all else fails, take it to the dealer.

As for running belts looser than tighter, remember that the belts will stretch as they heat up. As the belts stretch, they can become too loose, and jump a tooth or two. Once that happens, it's all down hill at that point. It only takes a one tooth slip to bend valves or destroy a cylinder.

And while you have your belts off, check the pulleys as well. I've seen older pulleys, mine included, that have worn and corroded, and cracked. It's an often overlooked spot, but it will destroy a belt quite easily if let go too long.

I just hate seeing folks screw themselves over trying to do things they may not be entirely familiar with. Yes, we all have to learn somehow, but there are right and wrong ways to do it.
 
#13 ·
Fair enough, duckwrench13. I do think it is good to do it the first time under the guidance of a mentor if possible. Would it be possible to post the latest belt frequency specs for the whole model range? I know some specs were superceded and what is in the manuals is not always correct.
 
#14 ·
duckwrench13 said:
As for running belts looser than tighter, remember that the belts will stretch as they heat up. As the belts stretch, they can become too loose, and jump a tooth or two.
I was under the impession that when the engine was hot everything expanded and moved apart so the belt tension increased?
 
#16 ·
Getting back to the original question...

I bought an 03 800 Monster that had sat for quite a while and changed the belts before driving it home. I set them with a 5mm allen. My ride home was about 1,400 miles. When I checked them at home they were very loose. They hadn't skipped a tooth but they looked like they were going to soon. I reset the tension and they have been fine ever since.

After a belt change I would recommend pulling the covers at 100 miles and then again at 500 miles to check tension. Only takes a few minutes. After that you should be good for the usual 6k checks.

As for setting the tension and DDS vs allen key, either can be used effectively for 2V bikes. If you've got enough mechanical ability to align the timing marks and install the belts properly you can certainly adjust the tension. An allen key certainly gets the job done and many people have used this method for years without incident. If trying it yourself makes you nervous go to a shop or find a knowledgeable friend.

There are lots of programs you can download fromt he internet to make your PC and a microphone measure Hz from the plucked belt. Much cheaper than the DDS if you don't want to use an allen key.

Always check that the tensioner roller bearings turn freely while you're in there. If these seize your belts can fail very quickly. And remember, a little loose on tension is better than a little too tight. Too tight and you wear seals, bearings, and belts prematurely.

Hope this all helps.

Scott
 
#17 ·
[/quote]
scott_araujo said:
Getting back to the original question...

I bought an 03 800 Monster that had sat for quite a while and changed the belts before driving it home. I set them with a 5mm allen. My ride home was about 1,400 miles. When I checked them at home they were very loose. They hadn't skipped a tooth but they looked like they were going to soon. I reset the tension and they have been fine ever since.

After a belt change I would recommend pulling the covers at 100 miles and then again at 500 miles to check tension. Only takes a few minutes. After that you should be good for the usual 6k checks.

As for setting the tension and DDS vs allen key, either can be used effectively for 2V bikes. If you've got enough mechanical ability to align the timing marks and install the belts properly you can certainly adjust the tension. An allen key certainly gets the job done and many people have used this method for years without incident. If trying it yourself makes you nervous go to a shop or find a knowledgeable friend.

There are lots of programs you can download fromt he internet to make your PC and a microphone measure Hz from the plucked belt. Much cheaper than the DDS if you don't want to use an allen key.

Always check that the tensioner roller bearings turn freely while you're in there. If these seize your belts can fail very quickly. And remember, a little loose on tension is better than a little too tight. Too tight and you wear seals, bearings, and belts prematurely.

Hope this all helps.

Scott
The same thing happened with my 2003 M800. I checked the belts after I bought the bike at 4500 miles, and the horizontal belt was dangerously loose. I re-tensioned it (Allen key technique), then replaced the belts soon after. Checking the belts after just 50 miles or so, the horizontal belt had stretched significantly, but the vertical was fine. Checked again at about 200 miles, only slight adjustment to the horizontal belt was necessary. So I agree, it pays to check and re-tension soon and frequently, after fitting new belts.

After a belt adjustment at maybe 10,000 miles, I noticed a high-frequency whining coming from the engine. Turned out to be too-tight belts, I'd rushed the adjustment and over-tensioned them. I believe one or both of the idlers was making the noise. Fortunately both bearings were good. Yes, a little loose is better than a little tight, IMO.
 
#18 ·
i'd run them for up to 1,000 km then reset them. often depends on the bike, but i'd definitely do them after that sort of time. i'll do cam timing with new belts, but i tell people to put some km on them before i remap something. could just be speculation of course.

we used the sonic tester from '02 until we had our dealership withdrawn in july and had to give it back. now we do it the old way again.

i use the old tensioner for 4v motors, setting them at 3. if i did this then set up the sonic tester it'd give 110 every time. i found the sonic tester ok on 4v motors where you had an eccentric adjuster, but on 2v motors there's so much difference with just a tiny movement that it's very frustrating.

plus when you rotate the motor it'll change. i always came up to the freq from below, but even then it was fairly inconsistant still.

i do the 2v motors by feel - loosen the adjuster and pull the bearings together with light pressure, then check for the clearance. it's fairly easy and consistant.

for some reason the 1000ds are very prone to noisy belts. most owners would call it "mechanic adjusted them too tight", but if we had a bike we'd set right that was noisy we'd just start loosening it off until it went quiet. spec was 140 - often you'd end up at 90 or so.

they get tighter when they get hot. a 1000 set to 140 cold might give 250 (or maybe 350, i forget now) when hot. but it's not that much tighter - my 750 surprised me how little it tightened when i was playing with it hot one day. the reason you do cam timing on desmoquattro with the belts over tight is to simulate this, but in reality all it does is retard the cams a couple of degrees as the even mechanics of expansion give a different result to just pulling everything toward the non tension side.

dunno why the 800 is so much tighter - it's indentical in every way to the 620.
 
#19 ·
Thanks to confirmation from Langanobob and brad black that the belts get tighter when they are hot so it looks like duckwrench13 doesn’t know everything when he said that they get looser when hot.
After us ‘amateurs’ have mastered the technique of checking and adjusting tyre pressures the next job we learn is how to change belts and particularly on the 2v engine it’s dead easy. There’s sufficient advice on this forum for a complete beginner to do the job competently without any need to have it checked by a dealer. Also enough guys have used the allen key method to prove that it does work. In fact a lot of guys who do their own servicing do it themselves because of the bad reputation that a lot of dealers have.
Anyway duckwrench13, stick around and you might learn something.:)
 
#21 ·
Before the harmonic tool was developed, Ducati used a simple spring scale that the Haynes writers determined to be 10lbs for the 2V belts.

I bought a decent 0-20 lb scale and made a hook to hold the idler pulleys while pulling the adjuster against the belt at 10 lbs and tightening the bolts. Coincidentally the 4 & 5mm allen trick matches these settings although not precidely each time.
 
#22 ·
Thanks for all the input . It has been a big help. I am going out tomorrow for a 100-150 mile ride so I'll check them when I get back. My old belts were the ones with white writing on them. Nice to have that piece of mind. I could turn them way past 45 degrees. This board is a big help for a first time ducati owner.
 
#23 ·
brad black said:
i'd run them for up to 1,000 km then reset them. often depends on the bike, but i'd definitely do them after that sort of time.
How often do you find you need to readjust them when you check em? I checked mine after 500 or 1000km the first few times I changed them, but they were always as close as I'm able to get to the "5mm allen key" spec when I checked them, so I stopped bothering... (I might go and check the current ones on the weekend, I changed them a week and a bit back and did a 2500km trip over new years...)

big
 
#24 ·
once they're reset once i think they're usually fine. but i always check my own bikes after around 1,000km. maybe even twice if i was really bored (not these days).

they can get quite loose, but the only ones i ever seen jump are the old 600/750 square tooth belts.