Chain came off...

[Shamrock]

I was out riding my NS 1 today when all of a sudden the chain decides to pop off. I pull over anyway and notice its hanging off on the rear cog. After about 10 mins(10 dirty, oily minutes) I manage to get it half way on and then I just rolled the bike backwards and it came on the rest of the way.
Anyway does this mean my chain is too slack? Do I need to tighten it?
Or was it just a freak occurence?
Cheers,
Shamrock!!

[Scooby]

lol yes it seems as if it is a wee BIT too slack....a few feet or so....

Check the chain tension.....push the chain up or down with one finger, there should be about 1" of slack....2" maximum.....

Hope this helps...
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A big enough hammer fixes anything!

[Shamrock]

How do you tighten the damn thing?

[Scooby]

I take it its too loose then....lol

You effectively move the back wheel back...look on your swingarm and there is a bolt you loosen that and there might be one on the other side of the swingarm, then move the wheel back till the chain is tight enough, don't make it so tight it will snap though. And make sure you keep the wheel aligned when tightening it back up, half a turn of each bolt at a time
____________________
A big enough hammer fixes anything!

[Shamrock]

Okay when you say there should be about 1-2 inches of play what do you mean? By that do you mean the amount of space there is when the chains pulled down and then pulled up?

[Milo]

In total, from top to bottom there should be about 5cm of movement. to tension it loosen the wheel nut then tighten the two longish nuts poking out the back. do it evenly until tight enough and then tighten the wheel nut. why not lube it while you're there?
also beware or a 15ish% power increase when you tighten the chain when it's slack.

[Shamrock]

Right theres actually about 4 inches of play on the chain!!
Hows that possible though? Dont the bike shops check this before they sell the bikes? Its not like it was adjusted since!!

15% power increase!! Sounds gooooood!

[Scooby]

Just out of interest, check your sprockets, if they're rounded the chain aint gonna stay on is it
____________________
A big enough hammer fixes anything!

[craigT19]

also if your chain was loose enough to come off youve probably caused premiture sproket ware on the front and maybe the back.
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Bikes owned :- 2001 nsr125, 1999 zx6r, 2006 yzf-r1, 2009 xmax 250, 2012 yzf-r1, 2015 MT-07
Current bike : - 2016 MT-10
BCF member pops. sadly missed 1945-2003

[batman]

you are gonna need to have the right tools to tighten that unless u want to send it to a bike shop
your chain slackens with use, and if theres 4 inches of play its well quite dangerous really :-)
my mate did the job on his ns1(tightened it), its not that difficult as long as its not stretched all the way as it is theres a marker on the swing arm
i can find out exactly for u from my mate what u need for the ns1(he has the stuff)

[batman]

just read that makes little sense!
my mate has the size spanners and wrenches u need to loosen the lock nut and the tightenin nuts at the back, i can find out what they are so u can save yourself some money

[air]

It should be the same as the 125, 24mm nut on the axel.
10mm lock and adjustment nuts.

Loosen the axel nut, put the bike on a vertical stand (or stick something under both swing arms to keep the back wheel up)
Loosen the lock nuts, (2 nuts on the screw at the end of each swingarm)
the lock nuts are beside the adjustment nuts which are right beside the swing arm itself.

Now adjust the lock bolts, best off to do it side at a time, so count about a 4 side turn on one side then do it on the other.
Spin the wheel and check for tension and tight spots.
Check the little "window" in the swingarm, it has lines ingraved into the metal and just make sure that either side is the same to line up the axel.
Tighten the axel bolt back up, tighten back up the lock bolts and bobs your uncle.

[Shamrock]

Okay I re-adjusted the chain now so it has the proper amount of slack,25-35mm. It seems to be ok. Im just worried that the wheel might not be aligned properly.
The distance between the axel nut and the end of the swingarm is the same on both sides but the little window with the notches is larger on one side. Thing is the window was different on both sides when I got the bike so Im thinkin the window aint very accurate!?
The tyre seems to rotate freely enough so Im hoping I didnt fuck it up.
Thanks for the help guys,
Shamrock.

P.S. batman its ok about the spanners etc, i have some tools lying around that did the job.

[Dylan]

Just check that the wheel looks straight, neither the window or notches are an accurate way of checking it.
Dyl

[Scooby]

go for a long ride then check your tyres are wearing evenly
____________________
A big enough hammer fixes anything!

[air]

Theres a few ways you can check, as it happens the notches on mine were perfect in the end (used a micrometer from the labs in college to check the exact distance)

Another handy way is measure the distance from the edge of the swingarm to the furthest point on the front end of the back wheel. If the distance matches on both sides then your wheel is aligned (or your swingarm is bent )

Don't use the screws as any indication as they're not supposed to be.
Using the notches on the swingarm and the above should sort you out.
Try riding unhanded, see how the bike responds to that compared to how it used to.

[McJamweasel]

Or, to check wheel alignment.
Go for aride with a mate, get him behind you and hell see if it snot straight.
Or, out it on a stand and make it go!! Stand back and then you can see for yourself.
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BCF: Be yourself, just don't be an arse.

[Shamrock]

Its probably just paranoia setting in but i felt i should try re-adjusting it so that the notches were at same lenghts on both sides. I got it a little closer so im feeling happier.
I dont have a proper bike stand so ive tried raising the back wheel on two crates. Its a bit dodgy tho. When I spun the wheel it seemed to move freely enough without any wobble. Guess ill just have to ride it for a while to fully notice that its ok.
Thanks for the advise,
Shamrock

[Milo]

you don't need a center stand of maintainence stand to adjust the rear wheel alignment. it's not gonna slip out of place because of the tensioning nuts on each side. as long as you do it the same amount each side then it'll be as aligned as it was before you started.

[Scooby]

Milo, don't waste your breath, it's damn obvious but some people just don't get it.....hehe
____________________
A big enough hammer fixes anything!

[Kickstart]

[Milo]

point 8)
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Shaft drives rule.