125cc pitbike problem with front sprocket

[vic1616]

hello again.
i took up my pitbike to my buds farm, drove it for a good 10 hours total. on the way back to the farm, i revved it pretty high in 3rd and did a late shift to 4rth. all of the sudden it feels like the bikes in neutral as im moving, so i look down and the chain is dangling. It was completelly off the rear sprocket and off the front sprocket . I put the chain back on the rear sprocket but couldnt get it on the front one as it was clearly out of place and pushed against the sprocket guard.

So i walked the bike back to the farm and undid the casing that protects the front sprocket. and saw that the sprocket was able to be moved COMPLETELY freely and i guess the bolt or nut came off and made the chain come off? i dont know someone help. I dont know what part i need to secure the front sprocket cause whatever was securing it came off. this is my bike. dont have other pics cause i left the ike at the farm. but basically the front sprocket is moving freely on the countershaft which obviously isnt normal lol

 

[miniracer39]

A little of movement is OK. Was it secured before with
this?

If you push the sprocket in, there's a spot on the shaft where you can rotate the lock, make sure it can't come out and then put the bike in gear and make sure it's on there tight Chinese bikes are known for loosen bolts, never seen a bike like yours so not sure if yours is a chinese or not.

 

[vic1616]

A little of movement is OK. Was it secured before with
this?

If you push the sprocket in, there's a spot on the shaft where you can rotate the lock, make sure it can't come out and then put the bike in gear and make sure it's on there tight Chinese bikes are known for loosen bolts, never seen a bike like yours so not sure if yours is a chinese or not.

yeah, it had to be locked in by that because something def went wrong for the whole chain to randomly come off both sprockets, it probably came off, and the sprocket moved outwards on the shaft towards the sprocket cover. but its weird cause the sprocket has the 2 screws on it still, but no bracket.

 

[vic1616]

If i get that bracket will it lock in on the shaft so it wont move on the certain area?

 

[vic1616]

and how do i put it on with that bracket? do i put bracket in first, then the sprocket and lock it together with the 2 screws?

 

[miniracer39]

First the sprocket, then the lock, move the lock into the freemoving spot and align it with the holes and then secure with the 2 bolts.

 

[vic1616]

ok,and are most 125ccs use the 17mm lock?

 

[miniracer39]

tough one, never owned a 125 hehe... try looking up from some manual online

 

[motodevo]

Just measure the distance between the bolts, there are 2 different spacings for the sprocket retainer

 

[vic1616]

what are the 2

 

[vic1616]

also, once i tighten the sprocket to the retainer on the shaft how will it insure the sprocket wont move along the countershaft and potentially fall off?

 

[my67xr]

measure across the outer edges of the splines inside the sprocket, it will be 17mm or 20mm.
also there are different size bolt patterns with the retainers too, i have a 28mm, 29mm, and a 30mm bolt pattern in my spare sprockets

17mm spline



20mm spline






28mm retainer pattern




29mm retainer bolt pattern





30mm retainer bolt pattern

 

[vic1616]

ok ill check thanks man for your help i think kine is the smallest bolt size and the bigger or smaller size bracket ill have to see

 

[vic1616]

******mine

 

[vic1616]

how exactly does is stay on the shaft tho once its held together by the bracket and screw?

 

[vic1616]

wont it just slip back off?

 

[my67xr]

when bolted together, the retainers' splines/teeth sit inbetween the splines/teeth on the sprocket.
and the retainers' splines/teeth also sit inside the slot cut into the output shaft too.

there isn't much chance of anything coming apart

 

[rotn50]

^^^^like he said

 

[zwebx]

you need some verniers man

 

[my67xr]

me?
i have a pair of Mitutoyos, but i can read measurements off a ruler too