[Duhastme]

The story is I recently put new tires on, and a couple cosmetic items (belly pan and swing arm cover for shock). So I drive the bike to work a couple times riding moderately hard and a couple wheelie's here and there, no issue's. This morning I go to bring the front up by clutching it and I feel a pop with a audible noise from the rear. I try to give it some gas and the bike feels like I have broken teeth on the sprockets. I stop and take a look at the chain and it is very loose, and the sprockets have no damage from the 1 or 2 min. inspection on the side of a highway. I am only a mile or so from my house so I lightly drive it home, if I give it light throttle the bike is smooth and no bucking. The bucking I believe is from the chain having so much slack. The question is what can I look for that would cause the chain to suddenly gain so much slack? Axle was still locked in place up against the adjusters.
In a time crunch as I have my first track day Sunday and I am hoping to still make it as long as i do not need to order some part.

P.S. I also switched my rear shock back to OEM along with the plates.

 

[smurfslayer]

Unless you broke a hard part - the swing arm mounts? or the swing arm itself, I’m at a loss to think of a place besides the chain adjusters themselves that could cause the kind of slack you’re talking about.

 

[Duhastme]

Unless you broke a hard part - the swing arm mounts? or the swing arm itself, I’m at a loss to think of a place besides the chain adjusters themselves that could cause the kind of slack you’re talking about.

I am with you there, I dont understand what would give that could cause that issue. I will check it out after work and report back.

 

[skidooboy]

check the rear sprocket hub/cush drive... look for the spacer that is supposed to be in the center of the back of the hub (the axle slides through it). sometimes when we swap rims, tires, we set the hub down, with the sprocket up, and the inside down, and this spacer falls out. (it will be laying where you swapped the wheel ) without the spacer, the hub will cock to one side and do what you are describing.

next look at the front and rear sprockets closely, make sure they are not missing any teeth at all.

if everything checks out, I would re-align, and tighten the chain. and go for a test drive.

sometimes when adjusting the chain, if you don't put a binder in between the chain and the rear sprocket to draw the adjuster blocks, all the way to the stop nut, it will pop the blocks forward to the stops, and loosen the chain.

my procedure is to loosen the axle nut, align the chain, set the slack, put a medium diameter screwdriver into the chain, rear sprocket valley, and rotate the wheel backward carefully so you don't damage the chain or sprocket (or the tool), until the slack is taken up, and the adjuster blocks are against the stops. hold the wheel in that position, tighten the axle nut to spec. roll the wheel forward, remove tool, and check for slack and alignment. repeat as required, until you are happy

I hope it works out, and you can make your track day. Ski

 

[Mike Jeffery]

Maybe you didn't tighten the rear axle enough and the rear tire slid forward... which would be the "pop" you heard and would account for the extra slack

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[Mike Jeffery]

Just something to check.

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[Duhastme]

check the rear sprocket hub/cush drive... look for the spacer that is supposed to be in the center of the back of the hub (the axle slides through it). sometimes when we swap rims, tires, we set the hub down, with the sprocket up, and the inside down, and this spacer falls out. (it will be laying where you swapped the wheel ) without the spacer, the hub will cock to one side and do what you are describing.

next look at the front and rear sprockets closely, make sure they are not missing any teeth at all.

if everything checks out, I would re-align, and tighten the chain. and go for a test drive.

sometimes when adjusting the chain, if you don't put a binder in between the chain and the rear sprocket to draw the adjuster blocks, all the way to the stop nut, it will pop the blocks forward to the stops, and loosen the chain.

my procedure is to loosen the axle nut, align the chain, set the slack, put a medium diameter screwdriver into the chain, rear sprocket valley, and rotate the wheel backward carefully so you don't damage the chain or sprocket (or the tool), until the slack is taken up, and the adjuster blocks are against the stops. hold the wheel in that position, tighten the axle nut to spec. roll the wheel forward, remove tool, and check for slack and alignment. repeat as required, until you are happy

I hope it works out, and you can make your track day. Ski

Thanks for the feedback and I will be checking these items when I get off of work. I am a little confused on the screwdriver part (bear with me I am a little slow
:badteeth I understand the part where you put it in the chain but am unsure as to the rear sprocket valley? I was having issues with the axle blocks not touching the adjusters after tightening, so I switched the axle over so the tightening force was pushing the axle forward. I will take a picture of what I try according to your suggestions.

 

[Duhastme]

Maybe you didn't tighten the rear axle enough and the rear tire slid forward... which would be the "pop" you heard and would account for the extra slack

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Will take a look at this as well, hoping it is something simple and not a hard part broken.

 

[Mike Jeffery]

good luck! And be safe

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[Mike Jeffery]

It's the chain loose enough to jump track? If so you may want to consider trailering it home. If that baby comes off it can do a lot of damage to you and the bike. I was just at my local shop and looking at a bike in the back ( I'm friends with the mechanic) that the chain jumped on. It bent the output shaft, cracked the case, broke the guys leg, and caused him to lay it down on the opposite side (right side) so it ruined his plastics and broke a clip on and brake lever, and he got some rash from the fall. Bike totaled plus a hospital visit, the rest of his season isn't looking so good.

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[Mike Jeffery]

Is the chain*

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[skidooboy]

sprocket valley= low rounded area between 2 teeth. motion pro makes a tool for this... https://www.motionpro.com/product/08-0642

I just put a wrench or a screwdriver in there, to add tension to the chain, to draw the adjuster blocks to the stop, and to hold it there while tightening the axle nut. Ski

 

[Capncalyx]

Thanks for the feedback and I will be checking these items when I get off of work. I am a little confused on the screwdriver part (bear with me I am a little slow
:badteeth I understand the part where you put it in the chain but am unsure as to the rear sprocket valley? I was having issues with the axle blocks not touching the adjusters after tightening, so I switched the axle over so the tightening force was pushing the axle forward. I will take a picture of what I try according to your suggestions.

I see what you're doing there and off the top of my head cant think of any reason that wouldnt be okay. Could it be possible that when tightening the axel nut - assuming you were tightening away from the bike or rear - that you may have pulled the axel blocks away from the adjuster stops a little and didnt notice? Then went for a ride and on a wheelie the weight of the bike all going to the back pulled the rear wheel up to the adjusters?? Im just not sure if the sheer weight of the bike could overcome the torque required for the axel nut. Just a hunch. Gotta be some reason your chain/axel blocks moved.

 

[Duhastme]

I see what you're doing there and off the top of my head cant think of any reason that wouldnt be okay. Could it be possible that when tightening the axel nut - assuming you were tightening away from the bike or rear - that you may have pulled the axel blocks away from the adjuster stops a little and didnt notice? Then went for a ride and on a wheelie the weight of the bike all going to the back pulled the rear wheel up to the adjusters?? Im just not sure if the sheer weight of the bike could overcome the torque required for the axel nut. Just a hunch. Gotta be some reason your chain/axel blocks moved.

That may be the reason, the only things that moves me away from the axle possibly moving is how much slack there is in the chain now. Like 4-5 inches of deflection now vs. the 2 inch I adjusted it for. I switched the axle so I am now tightening towards the front of the bike as well.

 

[Duhastme]

sprocket valley= low rounded area between 2 teeth. motion pro makes a tool for this... https://www.motionpro.com/product/08-0642

I just put a wrench or a screwdriver in there, to add tension to the chain, to draw the adjuster blocks to the stop, and to hold it there while tightening the axle nut. Ski

Ah ... that makes alot more sense for me now! Thanks for clearing that up. :thumbsup:


My assumption is that a hard part of some sort is broken.

 

[Capncalyx]

That may be the reason, the only things that moves me away from the axle possibly moving is how much slack there is in the chain now. Like 4-5 inches of deflection now vs. the 2 inch I adjusted it for. I switched the axle so I am now tightening towards the front of the bike as well.

Whew thats a lot dude. Did you notice if the blocks were sitting flush on the adusters right after it happened? Could it be the adjuster stop things arent holding for some strange reason? They have a "lock" nut on them too ya know :wink2:...just thinkin out loud here lol and all of us forget things from time to time.

 

[Mike Jeffery]

I see what you're doing there and off the top of my head cant think of any reason that wouldnt be okay. Could it be possible that when tightening the axel nut - assuming you were tightening away from the bike or rear - that you may have pulled the axel blocks away from the adjuster stops a little and didnt notice? Then went for a ride and on a wheelie the weight of the bike all going to the back pulled the rear wheel up to the adjusters?? Im just not sure if the sheer weight of the bike could overcome the torque required for the axel nut. Just a hunch. Gotta be some reason your chain/axel blocks moved.

U have to remember it's not just the weight of the bike trying to pull that forward... It's also all the power from the motor as well. And when he slipped the clutch it put an immense amount of torque on the sprocket trying to pull it forward all at once( plus the weight of the bike as you mentioned)

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[Capncalyx]

^^^^^^^ Sure, id believe all that...add to that hitting a small bump or something while wheelie'ing and something just gave way....the amount of slack its baffling though.

 

[Duhastme]

Whew thats a lot dude. Did you notice if the blocks were sitting flush on the adusters right after it happened? Could it be the adjuster stop things arent holding for some strange reason? They have a "lock" nut on them too ya know :wink2:...just thinkin out loud here lol and all of us forget things from time to time.

Yeh I forget many things, so it always easier to go through the basics before hand ccasion1

From the quick glance had, from what I saw nothing seemed to be out of the ordinary made sure to pay close attention to the axle blocks and the adjusters themselves and I did not notice anything out of place. Now mind you I was a bit rushed as I needed to get to work, head back home, switch bikes, Etc. Gonna get a go look over after work.

 

[Capncalyx]

So mysterious. Zoiks!