[hopz]

When I got this used bike, yesterday, the chain was really loose. I tightened it last night to normal specs.

Today I rode to the shop on another matter but I detected a rhythmic noise from the chain area. Related to speed of the bike but not the motor since I could de-clutch and coast and there it was scrunch- scrunch-scrunch. Something amiss.

In the garage I rolled the bike till I found the scrunchy spot. The chain was tight as Dick's Hat band. (For you youngsters- that means it was really tight.) If I rolled few feet forward or backward it was normal- loose.

By experimenting I found that at certain segment of the rear sprocket- for no known reason- the chain was not seating down on the teeth. This was what is apparently causing the chain to be tight then loose. WTF?

I have not removed the chain, nor the sprocket but neither appear to have been damaged. The chain is probably old and nearly worn out. I don't want to put a new chain into a bad situation.

I would appreciate your thoughts on the matter.

Bob

edit to add the bike has 18k miles on it- do not know the age of the chain/sprocket but bet its orignal.

 

[uglyDUCkling]

sounds like a bent rear sprocket / bent teeth. I have had this happen on my dirt bikes but never on a street bike

 

[Shazaam]

You need a new chain.

As a chain wears, it stretches and gets longer, but it doesn’t necessarily stretch the same amount at each and every link. So, in the future, in order to adjust the chain freeplay you first need to find the portion of the chain that has worn and stretched the LEAST. You then need to rotate the chain and check its slack in at least three different sections.

A chain should be replaced when it has stretched excessively. Each link in a new 520 or 525 pitch chain measures 15.875mm (5/8-inch) so 16 links will measure 254mm. When a 16 link section of an O-ring chain has stretched to 257mm (under a 20Kg/44lbs load) it needs to be replaced before it fails. When a Ducati chain snaps, it will often wedge between the drive output sprocket and the engine case, destroying the case and (hopefully not) locking the rear wheel in the process.

When a chain segment stretches, the distance between links no longer matches the distance between sprocket teeth so the chain won't sit properly on the sprocket, and if left on long enough will wear the sprocket teeth unevenly - so the sprocket may also have to be replaced.

So check the sprockets for an uneven wear pattern. The teeth should be symmetrical, not hooked in appearance. Replace them (if necessary) when you replace the chain.

Upside: This might be a good time to change your gearing.

 

[hopz]

Change gearing? I like that... please expand.

This thing is way higher than I want/need/use etc... lower is better- right?

 

[Shazaam]

http://www.ducati.ms/forums/showthread.php?t=28202

 

[hopz]

I read the thread, and the included attachments.
I knew the theory. I am an old motocross guy but before that we called it scramble, and enduros and... well you name it.

The chart in the reference does not list the 900SS.

Can someone just tell me the most common conversion- presumably the larger rear sprocket on the 900SS and number of teeth? The proper size and length chain too?

Do you guys still use chains with master links and link clips? Probably not.

Can you drop a hint about the best supplier and brand of the chain?

 

[Shazaam]

The 900SS responds well to either a 14-tooth front/same length chain or to a 3-tooth increase in the rear with a 2-link longer chain. Ducati's OEM chain supplier is DID.

 

[jcarruth]

I read the thread, and the included attachments.
I knew the theory. I am an old motocross guy but before that we called it scramble, and enduros and... well you name it.

The chart in the reference does not list the 900SS.

Can someone just tell me the most common conversion- presumably the larger rear sprocket on the 900SS and number of teeth? The proper size and length chain too?

Do you guys still use chains with master links and link clips? Probably not.

Can you drop a hint about the best supplier and brand of the chain?

I use EK MVXZ chains and use 15/39 gearing on my 97 CR. 14/39 is OK for the street, but you give up some mileage and top end for acceleration. These chains come with the best and easiest rivit type master links I have found.
I never use a clip type master link.

 

[st2lemans]

I like the 15/43 I have on my SS.

On my ST2, I use 14/43, but it revs higher than the SS so is actually geared for a higher top speed.

Tom

 

[rz33v4]

In your case I think I would replace both the chain (all of the high-end O-ring, rivetless chains are good these days) and the rear sprocket (go to a hard anodized aluminum rear, like Renthal or Sprocket Specialties). I am using a 14T front/40T rear combo which works fine on the street. For best results on chain life, keep it adjusted, clean and lubed using a chemical designed for O-ring chains, like PJ1 Blue Label or Maxima Chain Wax. If you maintain a new chain properly you should get very little thrown on the wheel rim and at least 10,000 miles on each before replacement.

If the chain is worn out I would assume your bike needs a couple of other maintenance items as well - cam belts and valve adjustment. Don't get too excited (the average biker thinks this is thousands of dollars on a Duck), as this should cost you $300-400 if done at a dealer. You might also consider having the electronics set up (injectors/timing) while there.

 

[vickon]

Just invest on a new chain and definitely a 15/39 sprocket combination, without a doubt. You will be very happy and glad you did... trust me!

Regards,

Vickon:abduct:

 

[REVNH]

I have run 15/40, 14/40, and 15/43. I like 15/43 the best.