Chain broke

[Scorpio65]

Doing about 25-30 mph in a turn and my chain came off... It messed up the sprocket bolts, and this morning i saw some oil leaking from the front sprocket cover.. My question is how do you replace the sprocket bolts and what could be leaking up front? thanks all..

[BaoQingTian]

You may wish to see my recent thread: "Help Bike tried to kill me" or something like that. 

If your chain broke, should should replace your front and rear sprockets at the same time.  I know some people have gone 50,000+ miles on one rear sprocket.  Empirically though, it's been shown that leaving the old sprockets increases the rate of wear on the new chain.

To replace the rear sprocket bolts, remove the rear wheel.  Then you'll remove the nuts (I had to use a Dremmel tool to clean up the bolt head enough to get the nuts off).  Then the sprocket lifts off and you can replace the bolts underneath. 

I have no idea where it would be leaking up front, sorry.  You'll have to pull the cover off and see.  Just remove the gearshift lever, and the 5 or so bolts on the front cover.  I slide it right off and let it dangle by the clutch cable.

[Scorpio65]

i saw your post, but i didn't see where it said anything about replacing the sprocket bolts or how to do it.. (My sprocket bolts look the same way as yours did) How did you change the bolts?

[Kerry]

Hopefully the leak is just flung-off chain lube that has been gathering behind the cover and was disturbed by the errant chain.  But it could also be from chain-caused damage to the crankcase.

The only way to find out is to pull the 5 bolts holding the cover on (very easy) and take a look.

[BaoQingTian]

Check your manual for more detailed steps, but here's what I remember.

1) Put bike on centerstand.
2) Remove the cotter pin and loosen the axle nut (being sure to keep the bolt head from rotating while you do so).
3) Slide the axle out while supporting the wheel.
4) Remove the wheel.  You might want to place a piece of wood between the brake pads to keep them from closing if you accidently hit the brake lever.
5) Set the wheel on something soft with the sprocket facing up.  YOu don't want to scratch the rotor up, so keep it directly off the concrete.  I used a rubber car mat that I use in the winter time.
6)Loosen then remove all the nuts.
7) Lift the sprocket off the bolts.
Then this entire dish-like piece will lift out of the wheel.  This is the piece that holds the bolts.  you'll see the heads from the inside.  They're flat on one side so they don't spin when you tighten or loosen.  Just pull the old ones out and put the new ones in.

[Scorpio65]

Thanks Bao..

[Queso]

so is there some bolts you are supposed to replace along with the rear sprocket?

[BaoQingTian]

Not as a matter of regular mainanence.  However, it sounded like when his chain came off, it mangled the bolts.  The same thing happened to me about 2 weeks ago.  I only replaced them because they were broken.