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ptxyz

broke my 1st chain today!

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some fun on my way to work.
 
after lane splitting through some tiny gaps (legal here), the blackbird was feeling frisky, having finally broken through to clear streets ahead.  briskly accelerating, the rear wheel slipped a bit on a grated manhole cover and then found traction on the pavement beyond...
 
acceleration abruptly ended, the motor rev'd and then the rear wheel locked up.  i was in the middle of the #2 lane and the cars i'd just passed up must've been either cursing or laughing at me...  actually, at least one of them recognized my predicament and sympathized "tough break"...  after getting the chain free (my gloves will never be the same), i was able to roll the bike up a nearby (conveniently) driveway and onto the sidewalk and then the last block to work.
 
i'll see if my ama membership or insurance towing will get me and the blackbird home this evening.  as i recall, it's an rk chain and it's only got a few thousand miles on it.  
 
some may recall another motorcycle related (imagine that?!) thread i started regarding the sprocket combo i'm running;
 
 
i've heard the 16 front sprocket can be harder on chains but, this caught me by surprise...  while i feel rk owes me a chain, i don't think i want to risk another break.  i'll get a closer look at things later and post up if i find anything else that may have contributed to this.  coulda been much worse, i was only going 30-40.  going home, i take the freeway!
 
paul

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Master link not done well enough? I’d suspect that over a random link failure.

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preliminary investigation reveals a sheared factory pin!  i'm somewhat relieved it wasn't my master link installation...

 

oh, and it appears to be a jt z3 chain...

 

chain failure.JPG

Edited by ptxyz

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That is fluke of all flukes.  I ran a 12/49 combo with a slick on the dragbird and never broke a chain.  Definitely a factory flaw.

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1 hour ago, ptxyz said:

preliminary investigation reveals a sheared factory pin!  i'm somewhat relieved it wasn't my master link installation...

 

oh, and it appears to be a jt z3 chain...

 

chain failure.JPG

5 bucks says something got between chain and one of sprockets. 

Inspect both sprockets.

 

Btw, 16/43 is r1 gearing. 525 chain.

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3 hours ago, tomek said:

5 bucks says something got between chain and one of sprockets. 

Inspect both sprockets.

 

Btw, 16/43 is r1 gearing. 525 chain.

Is that a judgement you made based upon your cam chain fiasco? What was the cause of that? 

What would have got between this chain and sprocket?

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How many miles on this chain?? The sprockets?

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Did the chain damage anything else?  BTW- I run a 16 tooth front with no issues so far and don't think that it has anything to do with your problem.

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12 hours ago, XXBirdSlapper said:

Is that a judgement you made based upon your cam chain fiasco? What was the cause of that? 

 

1v4kry.jpg

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A 16T adds a bit of pull, the slip & grab of the tire shock loaded it, but I think there was a defect, or maybe it got damaged at some point.  If you weren't at full power in first gear we can eliminate the 16T as being a factor.  If you were in a higher gear and not near full power the shock load probably would't be as hard as a drag race launch with a sticky tire.

 

I don't know what their warrantee is, but they at least need to know about this in case they've switched materials or there's a new process or something that went bad.

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Whats visible looks weird, not what I'd expect.  Is it sticking out on the other side?

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2 hours ago, SwampNut said:

 

1v4kry.jpg

 

fishing-cartoon6.gif

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had a close look at the rear sprocket, only damage i can see is from the chain getting caught up between it and the swingarm (locked my rear wheel, that was fun...).

 

sprockets and chain were replaced back in may, not sure of the exact mileage but, not more than a few thousand.  one trip to laughlin and 20 mile round trip commutes (shared duty with my klr).

 

watched my gopro footage and don't see any debris on the pavement leading up to this.  haven't yet noticed any missing fasteners or debris from me that might have caused this, i'll get a look at the front sprocket this weekend.  i'm hoping i just have to replace the chain.

 

other side of the pin looks just like the visible side.  appears to be a pretty clean shear.

 

so far, i'm inclined to believe it was the shock of regaining traction suddenly that caused a defective pin to fail.  here's a screen grab from my gopro showing that slippery manhole cover...  how fortunate work is only about 50-60 yards beyond!

 

"why the hell is that idiot pushing his bike down the sidewalk and through the crosswalk?!"

 

 

 

 

vlcsnap-2019-09-27-07h50m13s959.PNG

Edited by ptxyz

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If you were just leaving the light in 1st gear and accelerating hard I could see that being a significant shock.

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just got a better look at the damage...

sorry, the rear sprocket damage is kinda blurry. you can see a gouge in the swingarm and one of the nuts.

marks from the chain on the sprocket cover's inside.

chunk where one of the cover bolts goes broke it's threads out...

does the community think the remaining 2 bolts will hold? don't see damage to the sprockets. i'm debating just getting a new good quality chain or should i replace the sprockets too?

if i go the later route, i'm thinking spring for a supersprox rear and oem front (17/47). this jt front has a bit more play than i'd like...

IMG_3035.JPG

IMG_3037.JPG

IMG_3040.JPG

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jcrich, your thoughts on the now 2 bolt sprocket cover?  will they be enough?

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Lol I do not think you have much choice unless you are going to get a piece welded back on there. Torque them to spec and  Blue Loctite them or drill the bolt heads and safety wire them. 

 

And clean that sprocket recess out. 😀

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And clean the clutch pushrod also.  You could try JB Weld, don't think that there would be anything to lose.

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Supersprox rear is waste of money. Years ago I ordered one for my track bike, alu/steel version. It was heavier than steel OEM. lol.

Edited by tomek

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18 hours ago, tomek said:

Supersprox rear is waste of money. Years ago I ordered one for my track bike, alu/steel version. It was heavier than steel OEM. lol.

 

I don't know about that, I'm on my third chain with that very durable sprocket. 

.

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JB weld is way over-rated, and would never last for this application.

I would definitely file a warranty claim, and if you bought the chain and sprockets as a kit, ask them to replace the sprockets, too.  There is no way a pin should shear that easily on such a newish chain, even if it was a 520 chain.

On the cover, as long as the bolts that hold the clutch slave cylinder are okay (the long ones), you should be fine.  Unless, you break another chain, of course.  Consider yourself lucky to not have to replace the engine cases.  I think that steel spacer Honda uses behind the cover was a good idea, and probably saved you from a much more emotional post.

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So you would be on OEM or any other quality 

They claim their products combine durability of steel and weight reduction of aluminum sprockets. It is simply not true.

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9 minutes ago, tomek said:

So you would be on OEM or any other quality 

They claim their products combine durability of steel and weight reduction of aluminum sprockets. It is simply not true.

 

The truck driver has now become an expert in metallurgy and discovered a way to make aluminum heavier than steel!!

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