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How much driveshaft play?

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I just picked up a 2001 RM125 basket case for $800.  I have been going through it and it looks like a $800 bike.  The guy that had it before me said the guy before him put in a new crank.  New as in brand new or new as in another old one different than the original one, I am not sure.  It also has a new piston, clutch cover and spring perch on first visual, so, looks like a "little" money went into it.  

I was stripping it down to clean it and while I was taking the chain off, I noticed that there was a lot of play in the counter shaft (maybe).  If I put a sprocket tooth up to 12 o'clock position, I can spin it all the way back to 10 o'clock.  I have not had a 125 to play with, with the chain off, so, I am not sure, but, that seems like a little too much play to me.  I would think there should be 11:30 to 12 o'clock movement at most.  I assume it is okay as I would not think that the previous previous owner would waste time putting in a new crank and piston to have a crappy trans, but, then again, you never know. 

 

What do you all run into as appropriate free movement, play, of the counter shaft?

  

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Not untypical to have play. Though an 01 125 I'd expect also to of been beaten on and shined up for selling. If you are really concerned, split the cases and check.

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Oh, I now they have some play, it just seemed like quite a bit.  Being a manual trans, I am not sure where all that play would come from if it is locked in gear.  I am looking at pictures of the tranny online to imagine how.  I will break the case eventually, but, was trying to get an idea of what it could be before I went that far.  Yea, it is def a polished turd, lol, but, for $800 I could not pass it up since they go for around $1700 in "good" condition.  I can do a lot to it for $900. 

 

Thanks William1  :thumbsup:  :ride:

Edited by sikpupy

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I initially thought were referring to the "play" between the sprocket and the output shaft of the box. There can indeed be play in this area due to wear on the splines of the sprocket and the shaft.

However as you have added more info it appears you are describing "play" when turning the output shaft with the bike in gear. If this is actually what you are meaning then yes, you will have a fair bit of rotation of that shaft as the dogs of the gears by design have to have plenty clearance for them to engage / disengage with each gear change.

Constant mesh gearboxes mean the teeth of the gears are constantly in mesh, the path with which the drive takes through the gears is controlled by sliding gears or collars with dogs engaging with one another.

This isn't the best vid but gives you an idea of how it works. So with the clearance the dogs have, added to the backlash through both shafts and the clutch to crank primary gear you can get significant rotation of the output shaft when in gear.

 

 

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