1986 YZ125 build

soloman5000
Edited Date/Time 2/2/2016 11:26am
Hello all. Been toying with the idea of restoring a bike for a while now, but to be honest, didn't really think anyone cared about these old bikes til I found Vitalmx! Had no idea so many guys restore these things, and some of the finished bikes look awesome!! So after finding this site, I knew I had to give restoring a shot. I've been looking for an '86 YZ125 for a while since it was the first new 125 I bought, and was always my favorite bike. Found a few, but most were beat on bad. Recently came across one that was in fairly good and original condition (at least for these parts) and scooped it up for a good price. Already sourced some NOS parts (tank and shrouds) for the bike, and hope to start the teardown soon. Gotta do some research on the tips and techniques you guys use to restore your bikes, and find out good parts sources for these bikes.
Heres the sweet '86 YZ in as-purchased condition. Hopefully before long it'll start looking new again.


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mayzo
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mayzo 4/5/2014 10:53pm
4/5/2014 10:53pm
Great find, looks in good shape. I've recently got an 86 KX125 to rebuild. Ordered new linkage bearings and a few small thing but haven't had a lot of time lately to get into it.
pete24
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pete24 4/6/2014 3:21am
4/6/2014 3:21am
that bikes in great shape if you need to have the z spokes relaced hit me up ive done quite a few, and i got a decal source
MXM
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MXM 4/6/2014 8:21am
4/6/2014 8:21am
The bike you bought is in great shape, looks like most of the parts are all there and original. I can help if you have any questions since I just finished a 1987 YZ 125 restore and still remember were I got everything. You picked a good bike to restore since parts for these are pretty easy to come by compared to other bikes. I have some small nos parts left over from my build, will have to look and see what they are.
Ardfarkl
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Ardfarkl 4/7/2014 11:20am
4/7/2014 11:20am
That was my first 125 also. rode the CRAP out of that thing! Lots of fun.

The Shop

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soloman5000 4/10/2014 9:31am
4/10/2014 9:31am
MXM wrote:
The bike you bought is in great shape, looks like most of the parts are all there and original. I can help if you have any...
The bike you bought is in great shape, looks like most of the parts are all there and original. I can help if you have any questions since I just finished a 1987 YZ 125 restore and still remember were I got everything. You picked a good bike to restore since parts for these are pretty easy to come by compared to other bikes. I have some small nos parts left over from my build, will have to look and see what they are.
I can help if you have any questions since I just finished a 1987 YZ 125 restore and still remember were I got everything.

MXM that would be great! One question I have is how you got your YZ's rims looking so good? Send me a list of your parts or suppliers if you'd like.
Haven't done a total tear down of my bike yet, but did discover one of the subframe spars had been bent, then heated and rebent at some point. And missing some engine mount bolts and small things.
MXM
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MXM 4/10/2014 10:44am
4/10/2014 10:44am Edited Date/Time 4/10/2014 10:46am
soloman500, the wheels depend on what condition yours are in. Mine were straight and in pretty good shape without many deep scratches or scuffs, so I just cleaned them with wd-40 to get the old dirt and grease off, then used 000 "super fine" steel wool on the spokes/rims to make them shine. As for the supplier list that would be way to long; You can get most stuff from Yamaha still and then try e-bay for harder to find parts; After that you have to start calling Yamaha dealers to try and find nos parts you can't get at the other two places, you can also try Europe as they seem to always have parts for these 87's around.
soloman5000 4/10/2014 6:14pm
4/10/2014 6:14pm
Always find tearing stuff apart the most fun, so started to peek under the skin of the 86 YZ. Not too bad I guess, but definitely been some backyard work on the frame. Not sure what they added a plate here for...

and was obviously bent here at one point...

A broken front engine mount bracket...

and a missing engine mounting bolt...

And an obviously non stock air filter...

inside a cracked airbox...

Could have been much worse I suppose.
MXM
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MXM 4/10/2014 9:15pm
4/10/2014 9:15pm
I was so lucky my bikes never looked this bad, is that air filter from a 57 chevy? hehe
soloman5000 4/11/2014 5:43am
4/11/2014 5:43am
I think it came off an industrial motor or something, the owner had a lot of that stuff in his shop. Now I know why the side panel was bulged out a bit, the filter is too big for the air box.
And I wasn't happy when I saw the frame damage, that's the one part I was hoping was perfect.
soloman5000 7/23/2014 6:56pm
7/23/2014 6:56pm
Well, due to lots of overtime and kids, not much is getting done on the YZ. A bit more tore down, but nothing pic worthy. I did manage to score some new parts, including a pair or still-in-the-factory-wrapper NOS rad shrouds, a still-sealed-in-the-factory-box NOS gas tank (the last available from Yamaha in the U.S. according to the dealer), a NOS front and rear fender, and some other smaller NOS stuff. The one thing I can't find is a filter cage, new or used. How do these things just disappear? Same with an air box in good shape.
Hopefully soon I can really get some work started on it.
KIWImxer
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KIWImxer 9/10/2014 12:41am
9/10/2014 12:41am


I hope you're a bit further along than my 86 YZ125...
Payterrr125
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Payterrr125 4/3/2015 4:54pm
4/3/2015 4:54pm
soloman5000 wrote:
Hello all. Been toying with the idea of restoring a bike for a while now, but to be honest, didn't really think anyone cared about these...
Hello all. Been toying with the idea of restoring a bike for a while now, but to be honest, didn't really think anyone cared about these old bikes til I found Vitalmx! Had no idea so many guys restore these things, and some of the finished bikes look awesome!! So after finding this site, I knew I had to give restoring a shot. I've been looking for an '86 YZ125 for a while since it was the first new 125 I bought, and was always my favorite bike. Found a few, but most were beat on bad. Recently came across one that was in fairly good and original condition (at least for these parts) and scooped it up for a good price. Already sourced some NOS parts (tank and shrouds) for the bike, and hope to start the teardown soon. Gotta do some research on the tips and techniques you guys use to restore your bikes, and find out good parts sources for these bikes.
Heres the sweet '86 YZ in as-purchased condition. Hopefully before long it'll start looking new again.


Hey, I'm just starting out with my first dirtbike which is a 1986 YZ125. My dad got it for me and said if I can finish the cosmetic work on it he'd teach me how to ride and he'd buy a trailer and a YZ250 so we could go riding. The YZ is nearly in mint condition but with a few issues. #1 being the blown up motor, we just ordered the exact motor off of Ebay. After we get that all I need to do is get off all the yellowing on the gas tank. It looks like it sat in the sun for a thousand years and gasoline spilled on it for another thousand years. I've tried 600 grit sandpaper for hours and have not done anything to it. I don't want to paint it. I want it to the factory white color. Anyone have any tips. Also I used a scrapper thingy and it won't work due to the curvature of the tank. Any help to get me one step further would be extremely helpful.
reggie426 4/3/2015 6:24pm
4/3/2015 6:24pm
Don't worry about the frame, grind it back, tig weld it again and finish it with a flap disc or flexible grinding disc, then powdercoat. Just done the same with my '91, came out great. I had to reweld the entire rear, add a side cover bracket and fill the holes in the bottom.







smezmx
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smezmx 4/4/2015 8:25am
4/4/2015 8:25am
Payterrr125 wrote:
Hey, I'm just starting out with my first dirtbike which is a 1986 YZ125. My dad got it for me and said if I can finish...
Hey, I'm just starting out with my first dirtbike which is a 1986 YZ125. My dad got it for me and said if I can finish the cosmetic work on it he'd teach me how to ride and he'd buy a trailer and a YZ250 so we could go riding. The YZ is nearly in mint condition but with a few issues. #1 being the blown up motor, we just ordered the exact motor off of Ebay. After we get that all I need to do is get off all the yellowing on the gas tank. It looks like it sat in the sun for a thousand years and gasoline spilled on it for another thousand years. I've tried 600 grit sandpaper for hours and have not done anything to it. I don't want to paint it. I want it to the factory white color. Anyone have any tips. Also I used a scrapper thingy and it won't work due to the curvature of the tank. Any help to get me one step further would be extremely helpful.
You could buy a new clarke replacement tank or have your stock tank restored but both option's would cost a bit.$229 for a clarke tank.not sure how much to restore it back to new,but click on the links for more info.

http://clarkemfg.com/yz125-8688-stock-capacity-p-245.html

http://www.plasticrenovations.com
MaxPower
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MaxPower 4/4/2015 8:59am
4/4/2015 8:59am
Ive never seen a frame beat so bad there were holes in the bottom Reggie.
hotlugnuts3
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hotlugnuts3 10/28/2015 12:15pm
10/28/2015 12:15pm


Bought mine like this the crank bearing went out and it was seized just bought a 89 engine for it will it fit
toomey706
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toomey706 2/1/2016 2:37pm
2/1/2016 2:37pm
Did anybody ever find call filter cage or a manufacturer that will make them? I bought an 86 YZ 125 a few months ago of course missing a filter cage. I made one in my garage out of metal thought it was sealing pretty good but sucked a bunch of sand at three palms this weekend.
nicko-31
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nicko-31 2/1/2016 3:58pm
2/1/2016 3:58pm
toomey706 wrote:
Did anybody ever find call filter cage or a manufacturer that will make them? I bought an 86 YZ 125 a few months ago of course...
Did anybody ever find call filter cage or a manufacturer that will make them? I bought an 86 YZ 125 a few months ago of course missing a filter cage. I made one in my garage out of metal thought it was sealing pretty good but sucked a bunch of sand at three palms this weekend.
Toomey Same problem I',m having finding a cage along with a Crap load of other missing parts.No cages anywhere in the US.Sucks because my 85 was a pile when new and very hard finding parts I need to make it worth while.I've thought making my own cage also.

Pit Row

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pete24
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pete24 2/1/2016 5:11pm
2/1/2016 5:11pm
put this number in ebay rite now there is a 86 250 one on there and im pretty sure its the same
262231649727
nicko-31
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nicko-31 2/2/2016 10:41am
2/2/2016 10:41am
Does anyone know if those from 86 yz Air filter cage will work on the 85 filter cage ?? Thanks

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