First project - what next?

A

alexthe_great

New Member
Hey guys.

I recently bought a 1974 CB125s from a friend who let the oil run out and seized it. This is my first project, so I’m maybe in over my head.

I’ve torn the little guy down, and I was hoping to get some advice on where to go next with it. I know I need to get it running, but should I take it out completely and crack open the top end? If it’s seized, am I better off just putting a new Lifan engine in it and scrapping the seized one?

Any and all advice appreciated. Thanks in advance.
 

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I have a little CB100, it was seized too.

Just pull the top end, they're not that difficult.

If it's badly pitted put a bigger sized piston, have the jug bored, should do it.

Might want to take a look at trans parts too, since it was run w/o oil.
 
The thing about running 4 strokes without oil and seizing them is it's normally not just a case of a new piston and hone - it's more than likely a shot cam, lifters, big/small end and crank as well.


No harm in taking what you've got apart of course - but ultimately putting in a Lifan would probably be cheaper and easier after you buy gaskets, piston, bore / hone, whatever else you'll nedd to rebuild your current lump.


There's a stack of info about the swaps on the web so it's not rocket science.
 
What a nice looking little bike! I hope you intend to restore it, it's too good to do anything really radical with...but then again, it's YOUR bike. I've been working on bikes for 45 years; my advice is to see if you can get it running before you even consider a tear down, a lot of these old Hondas have really low mileage and only need a little TLC to get 'em up and running (you did say "IF it's seized").
 
Yeah, that's right.

Forgot to mention the cam, valves, and such in the head, probably messed that up as well. Especially the cam.
 
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