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Author Topic: First project - what next?  (Read 530 times)

Offline alexthe_great

  • Posts: 1
First project - what next?
« on: Jan 13, 2018, 02:03:29 »
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 Iím maybe in over my head.

Iíve 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 itís 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.

Offline The Limey

  • Posts: 407
  • Evil English Villain
Re: First project - what next?
« Reply #1 on: Jan 15, 2018, 07:21:16 »
Myself, I'd crack open the motor and see what the damage is before deciding.
I was born a rocker.  I'll die a rocker.  And I'm proud of it.

Offline WhyNot

  • DTT SUPPORTER
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  • Posts: 1153
  • ~~~If it ain't raining, I'm riding~~{iii}?~~prost~
Re: First project - what next?
« Reply #2 on: Jan 15, 2018, 08:56:51 »
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.
2006 Harley Davidson Heritage Softail
1975 Honda CB750K5 needs carb work
1974 Honda CB350F2 needs tins painted (being lazy)
1972 Honda CB175K2 roller no engine
1972 Honda CB/CL350 Engines need roller
1972 Honda SL350K2 Frame for above engine
1972 Honda CB100K2 needs kicker shaft
1990 Mitsubishi MM needs engine rebuild
1984 Dodge D50 Beater DD since 1997

Offline hillsy

  • Posts: 4117
Re: First project - what next?
« Reply #3 on: Jan 15, 2018, 19:58:50 »
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.

Offline goldy

  • Posts: 393
Re: First project - what next?
« Reply #4 on: Jan 16, 2018, 06:27:12 »
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"). 
1948 Norton ES2
1955 AJS 20B
1956 Triumph TRW
1968 Triumph T100 special
1969 Norton Commando
1975 XS650 Yamaha

Offline WhyNot

  • DTT SUPPORTER
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  • Posts: 1153
  • ~~~If it ain't raining, I'm riding~~{iii}?~~prost~
Re: First project - what next?
« Reply #5 on: Jan 16, 2018, 06:44:08 »
Yeah, that's right.

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

2006 Harley Davidson Heritage Softail
1975 Honda CB750K5 needs carb work
1974 Honda CB350F2 needs tins painted (being lazy)
1972 Honda CB175K2 roller no engine
1972 Honda CB/CL350 Engines need roller
1972 Honda SL350K2 Frame for above engine
1972 Honda CB100K2 needs kicker shaft
1990 Mitsubishi MM needs engine rebuild
1984 Dodge D50 Beater DD since 1997