1980 YZ125 In Pieces

Bman

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Apr 28, 2000
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#1
Wow, its been a long time since I've been here. Traded my 91 CR125 toward my customized 69 GMC last summer and haven't really been here since.

I have been asked to research something for a friend. I've already been told that we could probably pull it off, but want a second opinion so we don't dump money into something that won't work.

Heres the deal, a friend who really doesn't know much about bikes picked up a 80 YZ125 that had the engine/tranny in pieces. The previous owner was intelligent enough to tear absolutely everything apart despite the fact that all it needed was a top end. Well, my buddy wanted to get it running so he took it to a friend of his who told him he would want $600 CDN to put it back together, parts included. So this guy never touched the damn thing and then went off to school this fall. Everytime he comes home he just goes out and gets pissed and is now saying that he can't fix it. So all he has right now is a pile of used parts (which may not even be complete).

My friend doesn't really want to throw cash out the window, and is wondering if we could fix it if we picked up a shop manual for it. We are pretty good mechanics - top 2 last year in highschool (but I guess stuff like engine rebuilds/installation and valve work isn't quite as tough as tranny work). Do you guys with experiance think it is something we could tackle or are the parts now just paperweights?

If this engine is screwed, any ideas what might be an easy swap as far as other years go?
 
Joined
Jan 27, 2000
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#2
Welcome back Bman.

Sounds lke you guys could pull it off. Take your own suggestion and get a good service manual. Read it cover to cover. Read it again.


What you will learn about engines is well worth your time to attempt this project.

If you get stuck, there are many people on this board to answer your questions.

Go for it! :thumb:
 

jmics19067

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#3
If you have everything and all you are going to need is gaskets and maybe bearings and a piston/rings I say go for it!!!!!!! You could have a bike for relatively cheap. if it is going to need a lot of money I wouldnt unless a 1980yz125 holds some type of value to you.

But you could assemble it with out any money<trying to glue the gaskets together will the appropiate gasket cement> involved to see if it will fire up and the gears work for practice and then see if it is worth it to put money into it or sell it as a project/parts bike.
 
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Jun 30, 2002
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#4
It is definitely worth saving. A very cool and unique bike, last year of the air cooling but at the same time had the monoshock. Almost every internal part is still available from Yamaha or Bike Bandit.
 

Sawblade

Timmy Timmy Timmy!
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Sep 24, 2000
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#5
Bman,
I traded for a clapped out 1980 YZ 125 when I was 17. The bike was two years old and after riding it for a few times it stopped running. Learn and live being young and dumb, but thats another story. Anyway, all I had was the owners manual. I borrowed a fly wheel puller from some people I knew that raced Yamaha's and dug in. My Dad even bet me I couldn't get it running. After a complete tear down to rebuild the crank, replace all bearings, seals and clutch it went back together just like it came apart. It even started on the third kick! Moral of the story, get a manual and dig in! :thumb: