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Chain Mods

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Hey Will;


Can you weigh in here?


At the end of last season I started experimenting with changing ratios on my Ducati 748. My set up was a 14/39 which was a fine for a short technical track like Loudon, Shannonville Fabi or Pocono East but at a big track like NJMP's Thunderbolt Circuit, I broke my cam timing sensor with the bike pinned going down the front straight causing the motor to simply quit. After replacing the sensor I decided to take up a buddy's advice and look at my gearing. I swapped out the 14/39 for a 15/38 which was a huge improvement from a top speed perspective but I couldn't quite reach my goal of a 15/36 set up because of chain length; I couldn't move the excentric any further. Not having ever modified the length of a chain before (or even know where to begin) I decided to ask an expert how to do this SAFELY. The bike came with (I believe) a D.I.D. 520 chain and a quick change sprocket holder with a set of rears ranging from 36 teeth to 40 teeth sprockets along with extra lengths of chain; I then added a 15 tooth front to the package last fall.


Is this rocket science or can a novice mechanic do this and if so what tools are needed?





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  • 9 months later...

Hey Kevin,


I saw this wasn't answered yet and thought this was something that I can help with, but wouldn't you know it - I typed up a beaut post last night and I think I shut down my computer without actually posting it. rolleyes.gif

So here I go on attempt #2. laugh.gif


Short answer - no it's not rocket science. I've done chain & sprockets on both my bikes (GSX-R1000 and XR400), as well as changing brake rotors. All that stuff is very straight forward but you just need the proper tools like a torque wrench and a good chain breaker/rivet tool. I first tried with a cheap (even though it was still AUD$80) tool and it self destructed due to a design flaw that meant it couldn't even finish the job (I got a full refund at least). A cheap tool also requires you hold a spanner onto it for use as a handle. So you know what to avoid:





I use an RK tool - it's very easy to use, includes a handle which just makes the job a million times easier and unless you give up motorcycling you know that you will use it more than once (riding a bike with shaft or belt drive does not even bear consideration. laugh.gif ) This is the one that I use: https://www.motomummy.com/store/product.php?productid=16264&cat=274&page=1

Basically you will insert different parts into the tool for different stages of the job, full instructions come with it, but it's all fairly straight forward and you'll basically be using the tool as a small vise to either push pins out, or push side plates on.


To remove your old chain you'll need a Dremel, angle grinder or something to grind down the head of a chain pin so it's flush with the side plate. Then you use the chain tool to push out the pin - viola, chain removed. (If you're not changing sprockets you can use one end of the old chain to thread the new chain through.)


For your Ducati you'll want something with a rivet master link (my motard uses a clip type master link, which is fine for a 40hp bike. Not so much for a 140hp bike). Now you've gotta measure up to see what length you want your new chain to be, the motto here should definitely be 'measure twice, chain break once' because you can't put links back on. (Well technically you could use two master links, but that's something that I would shy away from.) Next up you'll connect both ends of the chain with your master link, the instructions with the chain tool will show which parts and how to do this. A good chain will come with some plates that you insert between the master link side plates so that you don't over-tighten when you rivet the pins. Another parts is inserted into the chain tool and this basically flares out the end of the chain pins on the master link to hold it all together. There's no harm in taking a few goes at this to get it right, I went a little bit too far and you can see it started to split the head on one pin:





Not that it's a big deal, I've been riding on it and it looks just the same now, but I suppose it's possible to completely mash up the pin so it would be weakened.


Sounds like changing sprockets will be a breeze for you, but for anyone else with a regular setup it's worth noting that the job is much easier if you loosen the sprocket nuts while the rear wheel is installed. You can either get someone to stand on the rear brake to try and hold the wheel (didn't work for me though), or you can wrap a breaker bar or similar in a rag and wedge it between the wheel spokes and swingarm to hold it still while you loosen/tighten the sprocket bolts. The rear sprocket nuts should be a self-locking type, and I use some Locktite on the front sprocket nuts/thread.


One important thing - do not try to tighten or loosen your sprocket nuts with the bike in gear! This will put unnecessary force on the gearbox & engine internals.


I think that's about it. A new chain will be coated in a thick, sticky type of protective lube/grease so it's worth cleaning the chain up once installed.

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In my opinion, you should never add links to a chain, you should never have more than one master link. Find a couple of size sprockets that will work for you and if you can't adjust within the tolerances of your chain adjuster have a chain for each set up.

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While I don't like to add links to a chain particularly if it's an older chain with new links there is absolutely no problem with adding rivet links master links into a chain. I have run as many as three in a chain. I didn't want to, I wasn't happy doing it but it worked just fine and got the bike through the race.


On the other hand I have a box of old 250GP chains that I pair up to make them long enough for my dirt bikes and run two clip links in them. Been doing this for years and will for a few more as I still have about a dozen chains.


Love the post with pics couldn't have said it better myself.

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You're welcome Kevin, glad to help!


So with the master links - can you usually buy a bunch of these separately without having to buy a new chain? I never really thought about that since I don't ever need to swap chains until it's worn out.


Thanks Will, good to know that I got it right.




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Hmmm... you just had to go and ask a tricky question didn't ya? tongue.gif Nah, it's not really that tricky...


I would say that a chain is done at the first sign of any sticking links (or any other signs of binding, or that it's not working properly). But having said that, sometimes a bit of a clean can help loosen it up. I try to keep it as clean as possible all the time though.


The other thing to check is the service limit for chain stretch. Obviously if it's stretched beyond the limit then it's done.


While we're adding additional trick questions - is it true that you only need to lube to stop the o/x-ring seals from drying out? I use Silkolene Chain Gel which sprays all over the chain anyway, but I read something that said there's no point to spraying lube all over the chain rollers and sprockets? Ideally I think I'd like to find something with a thin needle where I can just squirt the lube directly on the o-rings.

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The chain is worn when you can lift it off the aft most point of the rear sprocket far enough to see daylight between chain and sprocket. Also, if it's stretched very differently or, as mugget said, have sticking links it's time for replacement.


The longest lasting set of chain and sprockets I can recall having heard off was from one bloke at an Australian forum who got 77000 km out of them on his ZZR1100. He would clean the chain after each ride, spray it with a little WD40 and wipe it off again. I've also heard of people getting 40,000 km out of chains that they never lubed, although without lube they will be noisy as the rollers go over the sprockets dry.


Generally, the two things that wear out chains are dirt and being too tightly tensioned. Grease collect sand, which grinds away sprockets and seals. A tight chain will stretch in spots when the suspension bottoms.

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