Chain came off while driving!!

So here I am cruising down the road when the bike decides it want's to rev out and barely move.

I pull over thinking that either the clutch or the transmission was fried. I dismount and get to look around. I see what looks like aluminum metal shaving all over the swingarm by the chain. I'm like freaking great. I just got the thing back on the road and it tore the tranny up. Then I look and see the sproket teeth. I'm like "WTF, the freaking chain came off like my Mongoose in middle school!" I hold it on and roll the bike backwards and it pops on.

Now for my question. Do I just need to tighten the chain up or is there more likely a more serious problem that I need to address?

ETA: 77' KZ 750.

Seems to me that you need to pull the cover over the countershaft sprocket and have a look. I'm assuming that the chain isn't broken, and just came off on it's own. Is this bike new to you? Any idea how long that chain has been on there? Got any pictures of the sprockets?

If the countershaft sprocket is still in place and properly torqued, and if the sprockets and chain are not worn, then I would have to guess that it was a tension issue that caused it to de-rail.

And what did all those metal shavings used to be?

@ testarosa - Will do. I'm thinking that the rear sproket might need replacement. I have had the bike for a month or so. I imagine that the chain is most likely original. I just put a bunch of cash into the carbs, ingition, paint and such. Gonna have to wait on a chain and rear sproket.

@ texasKZ - I'm guessing that it is from the rim and prolly part of the front sproket and the case. Scared the tar outa me when I saw them. I got the chain back on and it drove fine the five miles back to work.

Nothing like leaving the State Taxman office after a visit on lunch to have your bike pull a stunt like this.

ETA: Which rear sproket should I put on it if I do replace it.

you know what...you be lucky.....

veby veby veby lucky........

chains circulating at high speed can do amazing things in a heartbeat...good you had no issues

that aside..take a peek in there and see...bet you can see some condition of the front sprocket ,peeking behind the area the chain goes into the cover,,, might be time for new chain and sprocket set.... but if the gear you have is fine and the (post a pic, i cant imagine the chain spinning and not eating more goodies) rear sprocket is in good shape....then lube and adjust and forget about


but damn gina...you be lucky....good for you

Lucky is right! I can't believe you just put the chain back on the sprocket and rode it like that. Picture this: You're riding along minding your own business with a truck behind you. Your chain pops off the sprocket again, but oh oh, this time it wedges betwen the sprocket and swingarm and locks up the rear wheel. This makes a long black stripe on the street followed by a long brown stripe followed by a long red stripe. I'm not trying to preach doom & gloom, but you really should be taking this maintenance thing serious. Not doing so can literally kill you and we don't want to lose anybody. Please be careful. Ed

if i where you i would now change the name from TESTED to Lucky Azz

all i have to say is lady luck was on your side man and dont forget it

now check that front and rear sprockets good and KEEP an EYE on the chain slack

not a harper but you one lucky basterd

I took care of it as soon as I got back last night. I didn't have access to tools where I was and not driving it wasn't really an option. There are some neighborhoods around here you don't wanna leave a motorcycle parked in.

There was a ton of slack in it. I adjusted it to where there is about 1-1.5" of travel in it.

Thanks for the concern guys. I know I was glad the damn thing didn't snap and wrap around my leg. I'll post a pic of the sprocket, chain and master link tonight.

1" is ok. 1.5" is too much slack. Ed

@ ED - Thanks, fixed it.

Here are some pictures of the sprocket and chain. What do you guys think? Should I replace the sprocket?

I know you can't really say on the chain without seeing the stretch on it. Notice in one of the pics. that there is a master link. According to the manual there should be. That tells me this is a replacement chain that is most likely not up to spec. Do you agree?

You need a new chain and both sprockets. Get a sealed chain, like an X-ring from Z1. They last a lot longer, and the initial cost is only slightly more. Replace it and get some good quality chain lube to keep it going for many miles.

That rear sprocket is toast IMO. Both sprockets and the chain really need to be replaced as a set. Trying to use any one worn part with any other new part will only wear the new parts out faster. Sucks to say it but it's the only right way to do it. I wouldn't trust a chain that has de-railed personally.

BTW that chain and sprocket has been replaced before. That rear sprocket is aluminum. I prefer steel sprockets for longevity.