Replace sprocket shaft w/o splitting cases?

wheelbender6 · #1 (**permalink**) 09-27-2009, 07:33 PM

After a lot of tinkering on my 48cc 2stroke, I have determined that the cross shaft, that connects the clutch to the chain sprocket (through the motor) is bent. It manifested as a clutch that wouldn't release, a lot of crankcase racket and increase in visible wobble in the chain sprocket AND the clutch assembly.

Can I replace the shaft assembly without splitting the cases?

If not, I may purchase a new motor and repair the engine with the bent shaft as time allows.

I read thru your teardown and buildup and it seems to indicate that the cases will need to be cleaved to repair this.

Any advice is appreciated.

**Norman** · #2 (**permalink**) 09-27-2009, 09:33 PM

you should be able to get the mainshaft out with out splitting the case just take your time. Try to dive the shaft out towards the clutch side one bearing will come out with the shaft once the shaft is out you can drive the other bearing out. Most all cases have shoulders that allow the main shaft bearing to go into the case so that the bearing will sit in the case flush or slightly below flush with the case.
If the shaft is bent it might be a little tougher.

wheelbender6 · #3 (**permalink**) 09-28-2009, 10:53 AM

Norm - My concern is that there is possibly a cylinder shaped pin and two keys in the shaft, based on the clutch diagram on the Spookytooth site (#19 & 21).
Will the keys and pin prevent me from removing the shaft? Thanks
http://www.spookytoothcycles.com/ima...-schematic.jpg

look here for help getting the shaft out
bicycle engine total tear down
permalink #9 I think

wheelbender6 · #4 (**permalink**) 10-04-2009, 12:55 PM

Norm - The cross shaft came out just as you said it would.
The shaft looks straight. However, the shaft bearing on the sprocket side had only 3 ball bearings left in it. Everything else appears to be good. Thanks.

**Norman** · #5 (**permalink**) 10-04-2009, 03:53 PM

you should be able to get replacement bearing at almost any parts store take old bearing with you it should have the numbers on it.
you can go back with sealed or just the shielded bearing. I'm guessing that a sealed will cost a little more. They should be around $5.00 or so some shops will try to screw you on the price. You might look up the price on line to get a better idea before you look at a store. I had a bearing go bad on a scooter wheel to the bearing to a bearing supply store in Borger,TX. The guy said it would be $20.00 for one I looked up the price on line place called bailey bearing they sold the same bearing 10 of them $20.00 free shipping guess who I bought from!

wheelbender6 · #6 (**permalink**) 10-10-2009, 08:29 PM

I was unable to punch out the bad bearing with a heavy screw driver and claw hammer. I will try again tomorrow with a 3/4" cold chisel and 3lb hammer I bought today.