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Discussion Starter · #1 ·
Two different 900t's went down today according to a few guys on the Facebook. With pictures. Chain case for both of them.

Both described the same. Apparently they felt the chain skip teeth. Tightened the chain. About 10 minutes later it skipped again. Tightened again followed by chain case failure.
 

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It sounds like there may be something there. Either related to the guide in the case, or potentially the pin not keeping the bolt from spinning.

For what it's worth, there is a pin hole on the bolt rather than the indented groove. Might be worth slipping the pin or at minimum a second pin in the hole to make sure it isn't loosening. I guess part of the guide has changed on the 2020's from the 2019's as well.
 

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Two different 900t's went down today according to a few guys on the Facebook. With pictures. Chain case for both of them.

Both described the same. Apparently they felt the chain skip teeth. Tightened the chain. About 10 minutes later it skipped again. Tightened again followed by chain case failure.
The one I read about is tuned. Ive always wondered if the tunes that increase horsepower put added stress on components like belts, chain cases, and drive train that they weren't designed for.

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Discussion Starter · #8 ·
There is a pin or dowel I guess you would call it which is bolted in from the back side. Dads last season lost this pin and scattered the case.
It's different than the pin that's in the tensioner bolt?
 

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Two different 900t's went down today according to a few guys on the Facebook. With pictures. Chain case for both of them.

Both described the same. Apparently they felt the chain skip teeth. Tightened the chain. About 10 minutes later it skipped again. Tightened again followed by chain case failure.
How many miles Where ,did their own service with a lack of lube ,Don't be afraid to run extra lube in these chain cases ,
 

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The one I read about is tuned. Ive always wondered if the tunes that increase horsepower put added stress on components like belts, chain cases, and drive train that they weren't designed for.

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I'd be very surprised if it was a chain/gear failure due to power increase . There are plenty of 1200's out there with 250-300 hp using the stock chain.
 

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I'd be very surprised if it was a chain/gear failure due to power increase . There are plenty of 1200's out there with 250-300 hp using the stock chain.
The stock chain is only safe for about 2500kms of trail riding at that power in my experience. Many of us switched to Hyvo for greater strength. Not sure what the lifetimes are now as it only takes one broken chaincase to start rotating chains out as standard maintenance. I pull them at 4000kms, about twice a season.

I have 6500kms on my 900 and the next time I'm in the chaincase it's getting a fresh chain. Lots less power but still a heavy sled that gets torqued on often.
 

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Discussion Starter · #13 ·
Both were under 1k miles. One was bone stock at 450 miles. The second had a tune at 850 miles.
 

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Discussion Starter · #14 ·
For what it's worth, all 3 that I know of were 2019's. And I guess there was a slight change in the chain case for 2020's
 

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the issue with the one 2019 posting yesterday was he did not have the clip in the hole....instead as per the manual on the bolt I assume to create tension to allow adjustment without removing clip...maybe the clip doesnt have sufficient tension or is in the wrong spot...but the hole is foolproof as the bolt cant move...others have argued with me on this and Ive maintained Id rather have it locked down with having to remove to adjust regardless of what the manual has stated...again...he did not have the clip in the hole...
 

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the issue with the one 2019 posting yesterday was he did not have the clip in the hole....instead as per the manual on the bolt I assume to create tension to allow adjustment without removing clip...maybe the clip doesnt have sufficient tension or is in the wrong spot...but the hole is foolproof as the bolt cant move...others have argued with me on this and Ive maintained Id rather have it locked down with having to remove to adjust regardless of what the manual has stated...again...he did not have the clip in the hole...
I just read the Facebook posts. Both seem to think the flat side pin isn't holding the tensioner bolt in place. But one guy also said his let loose at 1800 miles and he never adjusted it all last season. It let go one of the first rides this year. Had to be extremely loose if never adjusted since new. So if it is possible the pin is allowing the tensioner to back off, why not keep the flat side pin in the original position and add a second pin to the front hole? Then you can remove the pin from the hole and adjust as normal per the manual. Then add a second pin through the hole for added security.

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Both were under 1k miles. One was bone stock at 450 miles. The second had a tune at 850 miles.
Maybe a screwup when they were PDI'd. Did they come from the same dealer?

My buddy bought a used 850 and blew his chain case on the first trip out. 10kms in to the ride it started skipping, we tightened the chain tensioner a lot (10+turns) it worked for 200kms then ate it self.

We figured what happened is that the chain was overtightened when it was serviced, causing the tensioner slider to fail. When we tightened it the "arm" was putting tension on the chain until it wore out.
 
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