Bearing question.

killerbanjo

killerbanjo

Poor English kid getting into bikes and loves it!
Hey there, I'm currently rebuilding a 163fml Chinese motor (A cg 125/200 clone) where one of the gearbox bearings have popped. Its a needle roller (HK1712) that is 17x23x12mm. The only thing is the shaft the bearing should go into is 15mm and not 17mm. When I split the cases I was VERY careful, laying everything on a sheet so if anything fell it would have been caught, but I have not been able to find a bush. Here is a picture of the gear shaft (far right)
koKE8gA.jpg


And here is the bearing (taken just after I split the cases to show damage)
MUvXNrP.jpg


If anyone think there should be some sort of bush or that I am missing something please tell me! I believe this is the same layout of many Honda singles which might help.

Sorry about the nooby question but first time I have split a crankcase before - Edward.
 
I don't understand the question
the rollers ride on the shaft
it is common to have a washer there

you will need to remove that broken bearing shell
of course in oreder to replace it
 
That's a weird one because a 1mm wall bushing would be pretty weak... Is it possible the proper bearing is supposed to be HK1512?
Check to see if the shaft is hardened, if it is, my best guess is the wrong bearing was installed by the Chinese or PO.
 
What I took from his post is the bearing has an ID of 17mm and the shaft is 15mm, he's looking for the inner bushing.
I was mistaken on my previous post, the od of that bearing is incorrect.
 
You are correct. The bearing has a 17mm inner diameter but the shaft is 15mm. The bearing that came out (I have already removed it the picture was just for reference) was an hk1712. I have looked for a bearing that has a 23mm outer and a 15mm with a 12mm width but they do not seem to exist. Funny you mention that the wrong bearing could have been fitted as this is an almost new engine, I gave it to my friend saying if it fitted in my bike then pay me... He rode it without telling me or paying me for about a week I believe before issues. He gave me back the engine and an XL 125 in pieces and we called it even. The XL is almost ready to be put back together after lots of hard work and I would like the 200 to go into it, hence the rebuild, but this has really baffled me. It seems I either need a 1mm bush on either the inner or outer of the bearing, or a different bearing, that does not seem to exist!

Thanks for the help, Ed.
 
well you should look at the condition of the end of that shaft
if it was running loosely in that roller bearing all broken up it would show evidence of some damage ?
make me think maybe here was a sleeve on it
is the shaft hard? can you scratch it with a file ?
I don't really think that it would operate at all with 2mm clearance
 
Ill try scratching it tomorrow. I have put it away for now as its late here. As I said when I split the case I did it on a sheet and was very careful in order to not lose anything. The only thing that might have happened, is that the sleeve/bush could have disintegrated. I might head over to one of those China moto forums and see if they might know something.

Ed

EDIT: Ok I lied. I got it back out haha. Shaft has some minimal surface damage that can be felt with a finger nail. No real damage though only some scuffing, the shaft is still in good working order.
 
killerbanjo said:
Ill try scratching it tomorrow. I have put it away for now as its late here. As I said when I split the case I did it on a sheet and was very careful in order to not lose anything. The only thing that might have happened, is that the sleeve/bush could have disintegrated. I might head over to one of those China moto forums and see if they might know something.

Ed
Click to expand...
good luck !!
 
what you orderd is a plain bushing made to have a shaft run inside it
it is just totally unsuited and will not work at all :(
it is not a hard metal on the outside nor is it precision ground which is what you must have in a needle roller
take a look in the Torrington catalogue you may find what you need
 
aww man, I really can't find any others other than the ones I posted :( Ill continue tomorrow. Thanks for the help man!
 
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