1980 Yamaha YZ 125 G

SXS
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SXS
Edited Date/Time 10/7/2020 11:32pm
So this is my vintage project!
Bought it pretty much in a very good overall condition, raced it already in two vintage Enduro races. First one with a lot of mud and a broken rear mudguard and on the second scored a DNF. So eager to twist the throttle that I broke the cable... just ordered new throttle, clutch and front brake cable!
Next step is to tune the suspension, at the moment is way to soft... Thinking of using some of the race tech parts with my suspension tuner.
Here goes some photos:



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Brian_Bowles
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Brian_Bowles 5/6/2020 4:29am
5/6/2020 4:29am
Good looking bike. I have always wanted one of the old YZs. I love the yellow and the tank graphics. It is so much better than the newer blue stuff.
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MaxPower
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MaxPower 5/6/2020 11:28am
5/6/2020 11:28am
That's a great looking machine. I think you'll enjoy it even more once you dial the suspension
SXS
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SXS 5/7/2020 12:54am
5/7/2020 12:54am
Brian_Bowles wrote:
Good looking bike. I have always wanted one of the old YZs. I love the yellow and the tank graphics. It is so much better than...
Good looking bike. I have always wanted one of the old YZs. I love the yellow and the tank graphics. It is so much better than the newer blue stuff.
I own a 20’ Yamaha and do like a lot the blue, but these vintage yellow Yamaha are really cool looking!
SXS
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SXS 5/7/2020 12:55am
5/7/2020 12:55am
MaxPower wrote:
That's a great looking machine. I think you'll enjoy it even more once you dial the suspension
I hope so! I’ll give some feedback afterwards

The Shop

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riv187
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riv187 5/7/2020 12:15pm
5/7/2020 12:15pm
Welcome to the G club. There is a facebook page just for it. I restored my own G years ago and have raced it several seasons with various improvements. Some stuff from the H model like swingarm,shock,and larger intake boot,,,A kicker from 82 is aluminum (I still use the steel one though). I went with a later PWK 36 carb,,special v force,,pipe,silencer, dg head,83 YZ125 forks,,rebuilt stock 1981 YZ250 shock & spring in back. 1980 465 springs in front,,1981-83 YZ front fender is still available from Yamaha,,special porting. I'm very happy with the stock shock valve of a 1981 YZ250 in mine. Won many many races and a championship with my bike,,so it's worked and proven itself fast& reliable. You have a great bike to start with,,,even bone stock. I wouldn't say its the best trail racer,,,but can be made quite spunky with right changes.
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SXS
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SXS 5/7/2020 3:22pm
5/7/2020 3:22pm
I’ve joined a Facebook group about the “Gs”! Probably the one that you are referring...
Your bike by the amount of mods must be really fast! I would love to do some engine work but nothing too serious! Just a new piston and an aftermarket exhaust (the silencer is a DG).
Foot pegs are on the wanted list as well, thinking of using the ones from the CRF 50...
MaxPower
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MaxPower 5/7/2020 5:08pm
5/7/2020 5:08pm
Your 250 is in pretty good shape too. Is the 125 easier to ride in the woods? I had a 250 like yours. While I had a lot of fun riding it, I thought it sucked compared to my 81 Suzuki. I wouldn't hesitate to own one today.
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riv187
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riv187 5/8/2020 11:38am
5/8/2020 11:38am
SXS wrote:
I’ve joined a Facebook group about the “Gs”! Probably the one that you are referring... Your bike by the amount of mods must be really fast...
I’ve joined a Facebook group about the “Gs”! Probably the one that you are referring...
Your bike by the amount of mods must be really fast! I would love to do some engine work but nothing too serious! Just a new piston and an aftermarket exhaust (the silencer is a DG).
Foot pegs are on the wanted list as well, thinking of using the ones from the CRF 50...
I tried a couple different pipe/silencer combos. The stock pipe with a long DG worked very well. I honestly don't know for sure the silencer was for my G,,,or another year YZ125. When you get something used off ebay,,no telling if it was for what they advertise or not or something else...I tweaked it though and made it fit well. I have a pro-form pipe and matching shorty silencer on it now,,,but only because the stock pipe rusted out badly. The PFR took some new jetting,,,but can't say it mad the bike faster. Maybe a bit more mid range. I've ran a 2 cylinders on it. Stock at .060 over and a nos that I went crazy adding boost ports,,but ports otherwise still stock. This bike has been a evolution of tweaks and changes. I got to ride a bone stock one at Gainesville and it was then I realized how all the little things added up on mine to make it stronger. Much easier to ride with a broader powerband. If I said do only 2-3 things, 1) 36PWK from 88-91 KX125- much better response off idle and cleaner pulling. 2) v-force for it,,again better response idle to mid. I also would bump the compression with a thinner head gasket to get .030" squish,,,better bottom end and midrange.
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SXS
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SXS 5/9/2020 7:51am
5/9/2020 7:51am
MaxPower wrote:
Your 250 is in pretty good shape too. Is the 125 easier to ride in the woods? I had a 250 like yours. While I had...
Your 250 is in pretty good shape too. Is the 125 easier to ride in the woods? I had a 250 like yours. While I had a lot of fun riding it, I thought it sucked compared to my 81 Suzuki. I wouldn't hesitate to own one today.
The 250 isn’t mine, but from a big friend! The 125 is way much more fun cause you’re always pinned, and definitely much easier to ride in the woods.
1
SXS
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SXS 5/9/2020 7:54am
5/9/2020 7:54am
SXS wrote:
I’ve joined a Facebook group about the “Gs”! Probably the one that you are referring... Your bike by the amount of mods must be really fast...
I’ve joined a Facebook group about the “Gs”! Probably the one that you are referring...
Your bike by the amount of mods must be really fast! I would love to do some engine work but nothing too serious! Just a new piston and an aftermarket exhaust (the silencer is a DG).
Foot pegs are on the wanted list as well, thinking of using the ones from the CRF 50...
riv187 wrote:
I tried a couple different pipe/silencer combos. The stock pipe with a long DG worked very well. I honestly don't know for sure the silencer was...
I tried a couple different pipe/silencer combos. The stock pipe with a long DG worked very well. I honestly don't know for sure the silencer was for my G,,,or another year YZ125. When you get something used off ebay,,no telling if it was for what they advertise or not or something else...I tweaked it though and made it fit well. I have a pro-form pipe and matching shorty silencer on it now,,,but only because the stock pipe rusted out badly. The PFR took some new jetting,,,but can't say it mad the bike faster. Maybe a bit more mid range. I've ran a 2 cylinders on it. Stock at .060 over and a nos that I went crazy adding boost ports,,but ports otherwise still stock. This bike has been a evolution of tweaks and changes. I got to ride a bone stock one at Gainesville and it was then I realized how all the little things added up on mine to make it stronger. Much easier to ride with a broader powerband. If I said do only 2-3 things, 1) 36PWK from 88-91 KX125- much better response off idle and cleaner pulling. 2) v-force for it,,again better response idle to mid. I also would bump the compression with a thinner head gasket to get .030" squish,,,better bottom end and midrange.
Thanks for those advice! I might try those... Do you have de V Force references?
nicko-31
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nicko-31 5/15/2020 6:10am
5/15/2020 6:10am
The owner of Moto Tsanri has a trick 126-G
He would definitely be able to help.
2
SXS
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SXS 5/15/2020 6:47am
5/15/2020 6:47am
nicko-31 wrote:
The owner of Moto Tsanri has a trick 126-G
He would definitely be able to help.
Thanks
chrisg19
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chrisg19 5/15/2020 10:59am
5/15/2020 10:59am
The original MXA test...








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nicko-31
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nicko-31 5/15/2020 3:30pm
5/15/2020 3:30pm
I loved reading this time warp. 👍
1
Dick Trickle 5/24/2020 7:45am
5/24/2020 7:45am Edited Date/Time 5/24/2020 7:47am
Very nice G you have there, and i am glad your running it, and its going well.
I have two of the old girls on the go at the moment.
One is being built as a project show bike, and the other as a rider for some vmx meets.

We have been gathering parts from all over the world, and also getting fabricators and companies to modify, build and upgrade our parts.

Here is a few pics of some of the work we have completed so far. Both bikes are still in bits, but work should start soon on the rebuilds..



















And thats just a few of the parts and ideas we have. The rest include full titanium bolt kits, modified H swingarm, Mototassanari intake, H carburettor, HPI ignition, Jimmy Button bars and a mass of other stuff.

The G was the last aircooled YZ. It makes for some worthwhile projects..

























10
mayzo
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mayzo 5/28/2020 4:41am
5/28/2020 4:41am
Dick Trickle wrote:
Very nice G you have there, and i am glad your running it, and its going well. I have two of the old girls on the...
Very nice G you have there, and i am glad your running it, and its going well.
I have two of the old girls on the go at the moment.
One is being built as a project show bike, and the other as a rider for some vmx meets.

We have been gathering parts from all over the world, and also getting fabricators and companies to modify, build and upgrade our parts.

Here is a few pics of some of the work we have completed so far. Both bikes are still in bits, but work should start soon on the rebuilds..



















And thats just a few of the parts and ideas we have. The rest include full titanium bolt kits, modified H swingarm, Mototassanari intake, H carburettor, HPI ignition, Jimmy Button bars and a mass of other stuff.

The G was the last aircooled YZ. It makes for some worthwhile projects..

























So that’s your tank that was on Facebook the other day. 😎🙏👏👏👏 Serious $$$$ there.
Can’t wait to see the finished product 🤓
Will you be finished by the time Oz VMX resto or Classic dirt (if we’re out of lockdown) come around?
2
Dick Trickle 5/29/2020 1:17pm
5/29/2020 1:17pm
I don’t think so. We have two yz125ks that we’re trying to get running to race in a few Vmx meets. The G’s are just quietly plodding along in the background..
1
wfoyz250
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wfoyz250 10/7/2020 4:32pm
10/7/2020 4:32pm
I just acquired a "G".....what is the title of the facebook page?

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backinthesaddleagain 10/7/2020 7:36pm
10/7/2020 7:36pm
I loved those aluminum swing arms on those bikes. So much cooler than the black round steel ones.
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SXS
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SXS 11/19/2024 12:15pm
11/19/2024 12:15pm

Bike on the stand! Planning on doing some vintage enduro racing in December, so some maintenance and new enduro plastics on the way…

SXS
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SXS 11/19/2024 12:16pm
11/19/2024 12:16pm
IMG 7227 2.jpeg?VersionId=uzTLq2NpZAe8izM

 

IMG 7226.jpeg?VersionId=sRUxEuOa5GD7b8DMsps
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Inferno
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Inferno 11/20/2024 12:43pm
11/20/2024 12:43pm

Love the 80's yellow yz's😍

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SXS
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SXS 4/5/2025 8:25am
4/5/2025 8:25am

New exhaust for the old lady 

2BE404D9-F642-4F05-B6CF-B167093CA3FE.jpeg?VersionId=oVEKC.9qxgtqPG8E4x88598320B-ED96-4837-9949-19C3A597E4D2
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RednBlue
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RednBlue 4/6/2025 4:10pm
4/6/2025 4:10pm

That second photo in your string is the best - love that shot!

Coming off the start with the front wheel up sums up moto in one pic

Best friend had an '81 YZ 125 - still remember him dialing that thing in.

So glad people are keeping the old school moto vibe alive

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SXS
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SXS 1/9/2026 8:48am
1/9/2026 8:48am
IMG 7573 1IMG 7574 2
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