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Discussion Starter #1
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'm running a 16/44 sproket combo i installed with this chain (rk chain with jt spockets, i think) back in may. only a few thousand miles since then. 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!

i'll see if my ama membership or insurance towing will get me and the blackbird home this evening.
 

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Good luck. I really am happy with my DID Gold chain.

Sent from my SM-N960U using Tapatalk
 

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Discussion Starter #3
took a look at the remains on my lunch break. my memory didn't serve me, it's a jt z3 chain... last time i use their stuff.

one of the factory pins sheared. thankfully, my installation of the rivet type master link wasn't to blame...

chain failure.JPG
 

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Just glad it didnt ball up on the main shaft and split the case. I've run the EK ZZ series with very good results. I'm running the Z3D version now and my son is still running the ZVX3 lightened version.
 

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DID ZVM X ring is the only chain for a Bird, Your lucky you still have a complete motor in it,
 

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Discussion Starter #7
complete motor? kinda...

IMG_3035.JPG IMG_3037.JPG IMG_3040.JPG

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'll follow beestoys advice and spring for the supersprox rear and oem front. this jt front has a bit more play than i'd like...
 

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Discussion Starter #9
stex, did you have a similar break in your case? do you think the remaining bolts (2) will be enough?
 

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stex, did you have a similar break in your case? do you think the remaining bolts (2) will be enough?
I didn't break anything knowing the drive chain I needed for this beast (well to me it is) You are lucky that is all the damage and your OK.
If u have broken rear sprocket bolts then either repair or find some on ebay
U Need ALL Them Bolts :>)....don't gamble a few dollars for your life.

STex
 

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Is your front sprocket shaft bent at all,
You can see this by turning the sprocket over in Neutral,
The sprocket will wobble as it turns, If it wobbles, you will need a new shaft,

JB Weld, then drill and tap it for a new bolt,
TIG Weld it back in if you still have the bit thats missing,
 

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Discussion Starter #12 (Edited)
don't see any wobble in the countershaft spinning by hand, i'll start her up and get another look before i put things back together. new ek chain's arrived, i already have a 17t front, just waiting for the 47t supersprox rear.

i've been in email communication with someone at jt. they've been responsive and i've shared detailed pictures and information about the bike and my maintenance habits. they've also requested the failed chain for lab testing.

here are a couple of pics, a better one of the sheared pin and my hopefully adequate jb weld repair of the case.
 

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PT
You should be good with the upper bolt broken. Then clutch slave is going to load that bolt just above it primarily and the bottom bolt is the other part of the fulcrum point. So if you had a choice of which to break you got the right one.��
 

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Discussion Starter #14
it's actually the nearest one that broke out a chunk with the threads... my earlier pic of the chunk missing is sideways...

when i was removing the cover, my 1st clue something was wrong was that the upper bolt (not visible behind the frame) couldn't be removed (unthreaded) by hand after breaking free. doesn't appear to be damage to the threads in any of the 3.

if you look closely, you can see the upper part of the break, post repair, is off by just a hair. due to the way it fractured, i just couldn't get it any closer. hopefully, there's enough play in the bolt holes to make up for this.

hopefully, i get that rear sprocket in the next few days so i can get her back on the road this weekend.

as an aside, some of you may be pleased to hear i did absolutely no cleaning of that chain i'm going to return to jt!
 

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JT sprockets are usually as good as anything else but I'd recommend buying the oem Honda front sprox with the chain damper material...... I put JT sprockets on mine with a mid spec good quality chain (can't recall but it would be an EK or an RK etc Japanese quality that suits the bird). The BB is not really that powerful by today's standards, but I have found the non damped front sprocket to be noisy.

Changing the sprocket sizes alters the speedo readings too...... I stayed standard on mine which means I have 6% error with a 180/55 rear tyre...... or at present, a 10% error with a 190/50 tyre....... I wonder if a 180/60 profile tyre might correct the speedo next time I'm due new rubber......

My 05BB doesn't require lower gearing than stock...... it has always accelerated well and can still idle along in traffic without using the clutch.

I think your issue was the chain quality/rating....... the sprockets will be fine (JT are "round" unlike some nasty cheapies with poorly centered holes), but the weight of the Bird (260+kg's) means you need a good strength or high strength chain, not a budget strength or dodgy chinese copy.

Glad you didn't suffer case damage...... and if doing the work yourself..... be sure you rivet the joiner link just right.... not to much, not too little...... I saw on another forum, there is a riveting tool that is designed to cold crush the pins just right - wish I had known about them when I picked up mine.:crap:
 

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Discussion Starter #17
finally put the bird back together and went for a test ride sunday. refitting the sprocket cover was fun, seems the bolt holes are not quite in the same place. i also needed to shave that thick metal "gasket" that's between the cover & case, it was touching the clutch pushrod. clutch action is, thankfully, smooth.

in one of my better recent moments of "i can't believe i ****ing just did that...", i took out too many links to use my fancy 46 tooth supersprox rear... thankfully, the used ebay hub i bought (discovered the old chain damaged a couple of the sprocket mounting nuts / studs on it's way out) had a nice sunstar 45 tooth sprocket. i'll be back to stock gearing (17/45) for this chain...

jt's asking for a dollar amount without saying they'll pay yet.

i'm figuring a full refund of the defective chain sprocket set to start ($179). i had to order a rear hub, ebay used ($29). i spent about 4 hours total repairing the case with epoxy (seems to be holding) and replacing the chain and sprockets. my time's worth something and even @ say $50/hr, way cheaper than a shop.

do you think $400-500's reasonable?
 

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Discussion Starter #20
finally have resolution to this. not exactly what i'd asked for but, i'm satisfied, given the damage was minimal.



jt rep. i'd been in email communication with asked that i call this morning. from the gist of it, they're unable to determine the exact cause of failure. they found no problems with the rest of the chain and suspect some problem with the single pin that sheared.



jt will pay me $250 and a future chain / sprocket set. i'll use that set on my klr650 or new to me xt225. no more less that top tier drive products for the blackbird.



i've never been too picky about my chains. cheapest i've used was a $50 volar that lasted all of 3-4k miles before stretching to the limit of adjustment. never expected this type of failure. i'm now more careful of situations where the rear might regain traction abruptly (like slippery manhole covers and dry pavement). not sure if i could've reacted quickly enough to the sudden loss of drive and increase in revs that accompanied this failure and prevented the damage to the lower engine case but, it's something i'll always think about going forward.



hope this helps someone else avoid this whole hairball...
 
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