Checking Timing Belt Condition?

[Queestce]

Hey everyone,

I'm a new Duc owner, just purchased a 2006 M620ie this weekend. The bike has has factory 1000, 5000, and 10,000 km services (at a Duc dealership) and currently has about 16,000 km's on the odometer. Obviously it isn't too far from the big 20,000 km (12,000 mi) service... Still, I am changing the oil/filters and going through and having a good look at it before I ride any distance on it. I have heard and read about Duc belts requiring replacement every 2 years, or 10,000km. What I'm not sure is when/if my bikes belts have been done, I assume they would have been done at the 10,000km service but its not specified... That was back in Feb 2007, so its only done 5000 km in the last 3 years, and could potentially have 3 year old belts. I was planning to take the covers off tomorrow and just look at the belts condition, see if it is tensioned correctly still, has "spring in its step", not flaking or rotting, not leaving shavings of rubber on the covers etc etc. I assume if I do that and it looks all good, then I should be fine to keep them on until the 20,000 km service does arise? The covers seem easy enough to take off, it is just a case of a few allen bolts right? Nothing to watch out for? I'm not a huge fan of replacing things if they don't need to be done and its just a numbers game, but then again I'm also not a huge fan of valves going through my pistons 

Cheers for any advice!

Tom

[ducpainter]

I've run belts for 4 years.

They were more like plastic than rubber at that point with far less than the max mileage.

Check for pliability as well as obvious failure like pieces missing.

As long as you understand the risk of having one break go for the longer service interval.

[Slide Panda]

Seems like you've got a clear notion of what to look for, and what the results of dropped belt are. If you're really worried, belts are only $35 roughly each.

[Cloner]

Do you know how to check the correct tension, Queestce?  When you pull the covers the belts will probably feel like they're awfully loose if you've never fiddled with a set before.

The correct method is with a device that measures the frequency of the belts when plucked.  You hold a microphone up to the long run and pluck it.  The frequency should be within 5 Hz of 110.

If you don't have such a device (you can buy one at Motoreva, but they're not cheap), you can either fabricate one using a laptop, a cheap microphone, and sound analysis software (some freeware is available), or you can check approximate tension using a set of allen keys. 

For the allen key method you'll need 4, 5, and 6mm allen keys.  You'll use them like feeler gauges.  Check the clearance between the idler pulley (not the adjuster pulley) and the belt.  The 4mm key should "fall" through, the 5mm should be snug, and the 6 mm should be VERY difficult to shove through.  It sounds archaic, but it was the method of choice for two-valvers for a very long time before the frequency adjustment method came into vogue.  (the "factory" method used a device that looks like a fish scale to apply a preset tension to the adjuster pulley, but it was pretty inaccurate and rather a PITA)

Good luck,

Cloner
ABQ, NM

[koko64]

Belts have never been cheaper for the excellent quality available.

They can harden around the small diameter pulleys from lack of use and can wear on the tensioner and guide rollers. Some belts start to reveal the manufacture joint, crack up or shred from a bearing failure or incorrect tension. If the bike has been left sitting around by the previous owner, I would definitely change them.

Peace of mind for a small cost. 

[Queestce]

Cool, thanks for the help guys - much appreciated! I'll rip those covers off and have a look this morning. Had heard about that allen key test, cheers for the walk-through though. And koko I assure you if they don't look 100% roadworthy I'll order a new set asap, I'm keen on having this bike last me a long time 

Cheers!

Tk

[Queestce]

Just had a quick look. Not in ideal condition. They are not tensioned correctly, can slide the 6mm allen key through without too much difficulty. Plus there is a bit of rubber been slung around the covers, and the belts just seem quite dull and worn. Will order a new set so I know they are fresh! I figure I should be able to install them myself, setting up the timing can't to too hard, can it? I'm very confident doing things like oil changes, carb disassembly, fork oil changes, head bearings etc so I assume I could manage the belt replacement. Lots of good tutorials around anyway by the looks of it!

I'm not sure if I will try and by them from the US and have them shipped here to Aus, or just order through my local dealer and bite the cost. Does anyone know of a particularly good place to buy them online, or a good after-market company who makes them?

Cheers for the advice! Can't wait to get on the road on this beast - will be glad to know its all ship shape though!

Tk

[zarn02]

Does anyone know of a particularly good place to buy them online, or a good after-market company who makes them?

California Cycleworks markets their own brand of belts. Made by the same people who make the OEM belts, if I remember correctly. Not sure what overseas shipping would cost you.

And belt installation isn't too hard. Holding the cam wheels in place while you install can leave you with some frustration and sore fingers, but I've done it a couple times and it's not rocket science.

[ducpainter]

California Cycleworks markets their own brand of belts. Made by the same people who make the OEM belts, if I remember correctly. Not sure what overseas shipping would cost you.

And belt installation isn't too hard. Holding the cam wheels in place while you install can leave you with some frustration and sore fingers, but I've done it a couple times and it's not rocket science.

I don't think the ca-cycleworks belts are the same manufacturer.

[zarn02]

Hm. You might be right.

"Our belts are exact duplicates of the OE belt in every way utilizing the same core materials, the same rubber exterior, the same inner facing weave and exactly the same tooth profile. Our manufacturer is a global supplier of a wide variety of belt for transportation OE applications and has extensive experience making automotive timing belts for many major manufacturers."

Yup. Sure doesn't say they're the same company that builds for OEM. My bad.

[koko64]

Brad Black sells the Ca Cycleworks and OEM belts. See Bikeboy.org and 03) 9563 2004.

[Queestce]

Cheers for all the help.

Ended up with OEM belts as I found them locally for a good price. What an easy install! So much easier than other bikes I have owned. Have the new belts in, plugs in, fresh oil/filter, chain tensioned and lubed, cables adjusted and am finally planning a ride!

Tom

[Cloner]

Good on ya, Mate, for a job well done!  Now you get to feel the satisfaction of having done the work for yourself.   

For reference, if anyone cares, we at Desert Desmo install and heartily recommend California Cycleworks' Exactfit timing belts.  They are a good product and Chris is good people.