Topic: '82 CB125S Splitting the case - Issues removing these bolts - Oil pump

[natez]

Hey all,

Splitting the cases on my CB125S. The two bolts holding the oil pump housing on are stuck pretty good. I've got the right phillips head bit and even hit it with my impact gun. See the pic attached. I don't want to bugger it up anymore that I already did. Do I even need to remove this housing to split the cases? If so, any tips to get these guys out? I think they were over torqued by whoever was in there before me. Thanks for the help. I am splitting the cases to have the spigot bored out to accept 144cc cylinder sleeve.

[b52bombardier1]

Those are not Phillips head - JIS -- Japanese Industrial Standard. Looks like a Number 3 would fit perfectly. McMaster Carr carries a good set of Vessel brand JIS screwdrivers for maybe 40 bucks USD. Best investment in tools I ever made.

Rick

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[grcamna2]

Hey all,

Splitting the cases on my CB125S. The two bolts holding the oil pump housing on are stuck pretty good. I've got the right phillips head bit and even hit it with my impact gun. See the pic attached. I don't want to bugger it up anymore that I already did. Do I even need to remove this housing to split the cases? If so, any tips to get these guys out? I think they were over torqued by whoever was in there before me. Thanks for the help. I am splitting the cases to have the spigot bored out to accept 144cc cylinder sleeve.

I have an 81' CB125S and I was able to install the big bore piston/cylinder kit w/ the 61mm piston from Ebay no problem w/o having the cases bored.The 81' & 82' CB125S(if it's the original engine)both have the two-piece cylinder head,CDi & use the same lower case part numbers as the Honda XL185S.The spigot size on the stock engine on both those years is between 69-70mm so you shouldn't need to worry about boring out that spigot 

The JIS type hand impact driver is the only good way to remove those 2 cross point screws as they get locked on there tight sometimes.I would remove them and clean & check your oil pump for wear(#440 cast into the back of that housing and it's an improved size oil pump over the 1st gen. CB125S w/ the one-piece cyl. head)to be sure you get good flow when spinning those high rpms.

[natez]

Thanks guys. Ended up getting it out after another try.

I thought I had an '81 engine and the spigot was going to be done for me already, turns out my motor must be older (my motor is in a '78 Kawi KM100 frame, so it was never clear what year the motor was). It does have a two piece head but also has the older style stator so all things considered it must be a '78 or '79 motor. Nice little project though and I'm enjoying tearing down and the eventual rebuild of the motor. I have one case bolt that looks like its going to give me trouble now... I do have the JIS bit and a proper impact gun btw.

Nate