CB250 Main bearing removal?

[crackerjac]

Tearing down my Zong 169FMM and can't seem to get the crank and main bearing from the housing, it's stuck in there good which is strange because every rebuild video I've watch with regards to these motors the crank and main bearing seem to just fall out almost. Is there a trick to it I'm missing? Everything else has been removed from the housing.

Off topic a bit but this motor doesn't look like it's ever been opened and the tag says ZS169FMM which should be a 69mm bore and 62mm stroke, 232cc correct? It appears to be 65.5mm bore and 66.5mm stroke which is 223cc. It looks like they just through anything together at the factory. :( I guess it makes it a true CRF230F clone almost.

[humanbeing]

69mm = 17mm pin https://item.taobao.com/item.htm?id=541759022105 / 65.5mm = 15mm pin (as CRF230...) https://item.taobao.com/item.htm?id=540345088166
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https://item.taobao.com/item.htm?id=547321481833 There's also a variety using 68mm bearing| https://item.taobao.com/item.htm?id=13465193770
Timing chain: 102L | 104L

[ben2go]

The case will have to be split to get that bearing out. It will press out from the side that is in your picture to the inside of the case. A new bearing will have to be frozen for 24 hours, and dropped back into the case, before it gets any heat to it.

[crackerjac]

Thanks for the responses guys. Interesting that there are so many variations on the bore and stroke of these motors. They sure don't make it easy to determine what you have until you actually pull some of it apart and measure though. :(

It's not worth the money but has anyone ever used one of the big bore kits for the CRF230f motors on these?

I was able to carefully tap the bearing out without doing any damage to it. It just took a little bit to get it started then it came right out. I'm surprised that there is little to no wear on any of the components. Pretty good quality I have to say.

[Rangerscott]

Its irritating they call the engine a cb250. Any time you search that, it always brings up the old Honda twin cylinder cb250 stuff.

I got a 169fmm that I need to completely tear down, check, then put back together. All I can find is CG250 gasket sets. The bottom cylinder gasket is different from the two. Guess I'll just make one.

[crackerjac]

Originally Posted by Rangerscott

Its irritating they call the engine a cb250. Any time you search that, it always brings up the old Honda twin cylinder cb250 stuff.

I got a 169fmm that I need to completely tear down, check, then put back together. All I can find is CG250 gasket sets. The bottom cylinder gasket is different from the two. Guess I'll just make one.

Is your 169FMM a true 69mm bore and 62mm stroke or like mine above which is 65.5mm bore and 66.5mm stroke? I found a complete gasket kit for mine with correct everything on Aliexpress.com for a very cheap price.

[Rangerscott]

Originally Posted by crackerjac

Is your 169FMM a true 69mm bore and 62mm stroke or like mine above which is 65.5mm bore and 66.5mm stroke? I found a complete gasket kit for mine with correct everything on Aliexpress.com for a very cheap price.

I think its a non-true 169. I'll double check a thread i made about it awhile ago. I took off the big chrome plug that houses the screen filter and there was a good amount of metal pieces you could make 10 grit sand paper out of.

[Rangerscott]

Mind posting the link?

[pete]

Originally Posted by ben2go

The case will have to be split to get that bearing out. It will press out from the side that is in your picture to the inside of the case. A new bearing will have to be frozen for 24 hours, and dropped back into the case, before it gets any heat to it.

no no no...

Heat the case around the bearing..
you can not surport the case close enough to the bearing as the crank is
in the way...you risk doing damage...
heat it.. it won't need alot of heat.. hot air gun may be all it needs..




..

[ben2go]

Originally Posted by pete

no no no...

Heat the case around the bearing..
you can not surport the case close enough to the bearing as the crank is
in the way...you risk doing damage...
heat it.. it won't need alot of heat.. hot air gun may be all it needs..




..

He got it without heat. We have different techniques. I use tubing to support the area around the bearing and press the bearing into the tubing. It's close enough to allow the bearing to fall through. I've done it this way since I was a kid rebuilding my dirt bike engines.

[BlackBike]

[Rangerscott]

Found the old thread. Mine is the 65.5mm bore and 15mm pin.

http://www.chinariders.net/showthrea...ghlight=169fmm

I wonder why ZS would make two 169's.

[pete]

Originally Posted by ben2go

He got it without heat. We have different techniques. I use tubing to support the area around the bearing and press the bearing into the tubing. It's close enough to allow the bearing to fall through. I've done it this way since I was a kid rebuilding my dirt bike engines.

And everyone dose it that way.. but if you look at the pic he posted....
the crank is still in ... bearing pushes out of the case towards the crank...
So how do you put a a length of tube/pipe around the bearing....




..

[ben2go]

Originally Posted by pete

And everyone dose it that way.. but if you look at the pic he posted....
the crank is still in ... bearing pushes out of the case towards the crank...
So how do you put a a length of tube/pipe around the bearing....




..

Yeah that's true. Use wood blocking on the back side and get ready to catch it. He could also use L blocks but that is kind of a specialty item for hydraulic presses.

[crackerjac]

Arrg, been busy and finally getting back to this thing. I have the motor 90% back together and happy to say everything internally looks very good.

I don't know about the rest of you but I can't be the only one that watched the probably one video on YouTube in Russian that the guy shows rebuilding one of these, lol.