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Howdy,

I bought my 2016 Thruxton 900 EFI (air cooled) used with 4k miles, at 9k miles I put on a 19 tooth front sprocket. The bike now has 19k miles of riding the backroads of north Texas, I like to ride fast but I;m not aggressive.

I typically lube the chain every 300 - 500 miles (I don;t ride in the rain or on dirt roads) and at the same time I check the chain slack. Using this procedure:

I put the bike on the side stand, straight up, and adjust the slack to ~ 1.5 inches, I also check the alignment by measuring the adjustment bolts with calipers and a ProMotion tool clamped to the sprocket. This has work well in the past.

But the last couple times I noticed that once I was done and started to roll the bike around the garage, it was noticeably more difficult to push. So I would check the chain tension again and it was good.

Or it was too tight and I would loosen the tension and as soon as I got to the end of the block I could hear the extra chain slack slapping around.

So this weekend I put the bike on the scissor jack and with the weight off the rear wheel I would spin wheel and there appears to be two spots in chain that there is virtually no slack while the rest of the chain has up to 2 - 2.5 inches of slack.

video of the chain tension, Checking-Slack

I noticed that couple links do not "straighten out" and when they are at the bottom of the rear sprocket, there is no slack.

Automotive tire Hood Motor vehicle Rim Automotive exterior


I also did the chain stretch check as per the manual and it appears to be about 12.75 inches which is bit more then the spec of the 12.63 inches (its not that easy to make a arcuate measurement on this one)

I'm thinking I need a new chain but wanted to get second opinion, as I've seen guys report 30k or more miles on a chain.

The other thing is the manual says this bike comes with a 525 chain, but my bike has a 520 DID, so it appears the original owner replaced the 525 with a 520 at some point (why so soon on new bike?) I know its a 520 because the rear sprocket is stamped 520 (43 tooth) and when I ordered the front sprocket I looked at the manual and order the 525 and when I got it did not fit, I returned it for a 520 not thinking much about it.

If I do replace the chain I was planning on going with a good quality DID 520 as from what I understand 520 should be plenty strong for a my bike.

thanks
Automotive tire Hood Motor vehicle Rim Automotive exterior
 

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That is a really good example of a chain with seized links. Thanks for sharing.
Looks like your are missing a bolt too (or is that from the removed cover) and I am a bit concerned that the oil filter is supporting the weight of the bike - it's not right?
New chain & sprockets needed ASAP and I'm going to recommend you increase your chain lubing regimen. Just not slimy enough in that front sprocket area.

Too much slack can cause the chain to start cutting into engine casings, which is.....
 

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Yep, new chain time. That link that won't straighten out will kill your sprockets in double-quick time - if it hasn't done so already.

Personally I'd replace both chain and sprockets at the same time. Partially worn sprockets will prematurely wear out a new chain and vice versa.

The final year(s) of our bikes came with a 520 chain from the factory - a decent 520 chain can cope with a 150hp sports bike, so our 60+hp on a good day isn't going to be a problem.

Tim

~'05 Thruxton~Sport Evolution 1100cc~FCR 39mm~813 cams~+1.5mm valves~oil-in-frame cooling~Ignitech CDI~m-Unit~Acewell CA85~F3 Frankenfork~Hagon Nitros~6-piston Pretech~520 chain~wide 17" rims~tubeless conversion~Michelin Road 5~
 
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To reiterate what @RichBinAZ said: your chain lubrication regime needs looking at - either reduce the mileage between lubrication or change the lubricant.

Tim

~'05 Thruxton~Sport Evolution 1100cc~FCR 39mm~813 cams~+1.5mm valves~oil-in-frame cooling~Ignitech CDI~m-Unit~Acewell CA85~F3 Frankenfork~Hagon Nitros~6-piston Pretech~520 chain~wide 17" rims~tubeless conversion~Michelin Road 5~
 

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I guess I should be lubing the chain more frequently
Not necessarily the cause of your failure. Modern chains are sealed, meaning that the pivot pins are lubricated from within. Yours is a pivot pin lubrication failure, meaning that the sealing rings and/or internal lubricant has failed. Chain lube can't and shouldn't compensate for that.
Chain lube on a sealed chain is designed to lubricate the roller and side plate to sprocket surfaces.
 

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I lubed mine with the same Dupont product every 500 miles. When I sold the bike, the EK chain had 20,000 miles on it and wasn't in need of replacement.
 

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Yours is a pivot pin lubrication failure, meaning that the sealing rings and/or internal lubricant has failed.
Flash Nick makes sense to me.

I have come across info indicating that using some kinds of chain cleaners is not good. I read that it seeps behind the 'sealing rings' and pollutes the internal lubricant.

The road to hell is paved with good intentions, right? Could the 'extra care' of the previous owner using chain cleaner led to seal failure and cause a lockup like in BugStompers picture?
 

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OEM quality chain has a 20,000 mile life expectancy. Some people will get more, some people get less. "Tight" chains wear faster than loose chains. Alignment and Lubrication matters. Better quality chain lasts longer as does the sprockets. Same brand of sprocket front and rear. It shouldn't matter, but it does. Lubrication. I use VP Racing chain lube followed by White Lithium Spray. The filthiest, flings like made mess you have ever seen. But it works. I am really bad with chain maintenance. I am not kidding when I say I only do it every 1500 miles tops. My Sprocket Center 520 conversion with EK 520MVXZ - CHROME X'ring chain has over 30k on it...still like new.
 

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For future reference, almost every chain will have areas that are tighter. You should find this area and do your chain adjustments/measurements based on the tightest spot. If you’re able to get a rear stand or some other method (that doesn’t involve supporting your bike by the oil filter) that allows you to spin the rear wheel freely it is much easier.
 

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Good point about the chain tension. I always kept mine at the loosest end of the range, when parked on the center stand. That seems to have worked well.
 
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