Changing sprocket! please help!

[IamCornholio]

Pertaining to the direction of the threads on the pinion (front sprocket) commonly found on cagliari type bikes and the removal and installation of new pinions + the use of 'spotwelds' on pinions to secure them in place...


Pictures below are the only things one will NEED to remove and install a front sprocket on a 'cag'... (less the oven of course )

A screwdriver to lock the assembly in place, a sprocket wrench for 'unscrewing' the pinion, and some Permatex 'red', threadlocker to make sure it does NOT come out...



The oven is ONLY needed to ease with the removal of bearings and such and to help 'loosen' the bond that the Permatex will make if one is trying to remove the pinion... (It takes 500deg to loosen the seal here) This WILL make SURE that the pinion does not come loose when it is not wanted and will set-up fairly quickly IMHO...




IamCornholio (and I really hope this helps someone using the 'search' button someday as that IS all I was trying to do here...)

[Gadgit]

Hay there CornHolio
I dont use thred locker because it makes it harder to remove the sprocket when you break one or want to change gear ratio... the engine spins in the direction that tightens the sprocket up so no way the sprocket is going to undo it's self while racing.. well I'v never had one come out in the 3 years I have been racing anyhow.

[IamCornholio]

Hay there CornHolio
I dont use thred locker because it makes it harder to remove the sprocket when you break one or want to change gear ratio... the engine spins in the direction that tightens the sprocket up so no way the sprocket is going to undo it's self while racing.. well I'v never had one come out in the 3 years I have been racing anyhow.

The threadlocker can be loosened either by heating the entire assembly in the oven for a few minutes at 500deg or by using a small 'pentorch' directly on the threaded pinion for a few seconds or so...

You are absolutely correct about the pinion getting tighter as you accelerate friend. Most pinions that 'unscrew' do so on deceleration. All it takes is a single bad bearing to cause enough drag to break even a welded pinion on a 'wound-up' engine when one lets off the gas...

I am very slow with building engines for our bike but they tend to have good power when finished and most parts that can't 'hold up' generally fail quickly...

Here is a pic of the pinion that 'unscrewed' on me. I have other friends on other sites that have experienced this as well. It CAN happen if one is not careful with their maintenance and pre-ride 'checks'...



If any of this helped you with your pocketbike... That was a good thing IMO...



IamCornholio

[newmanz]

Ok, I am lazy and in the past have just replaced the whole clutch bell with sprocket already installed. I have had clutch bells with factory threadlock glue that was impossible to remove without using a torch to heat it up and most times this heat passed straight into the bearings and stuffed them.

For the price, a sprocket tool is a nice friend. I think for the first time you ever change the front sprocket it really is a bit of hit and miss,especially if you have not read up on thread directions... after that, because you have done the job yourself, its always easier.