1979 yz125

cr2507354
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cr2507354
Edited Date/Time 11/14/2020 5:59pm

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cr2507354
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cr2507354 10/29/2020 1:20pm
10/29/2020 1:20pm
Picked up this 1979 yz125 for 300$ a couple days ago. I don’t plan on painting the frame or doing a bottom end. I plan on racing this bike in the local vintage races.
cr2507354
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cr2507354 10/29/2020 1:25pm
10/29/2020 1:25pm
The engine was filled with gas😂 I was trying to start the bike when I got it home and it was spraying from the pipe so i just started taking it apart. Other than it being flooded the engine feels tight and looks good. A new top end should be fine
cr2507354
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cr2507354 10/29/2020 1:31pm
10/29/2020 1:31pm
Don’t want to spend tons of money on this bike so instead of buying a new pipe I just gave the stock pipe a works finish
2

The Shop

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cr2507354
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cr2507354 10/29/2020 1:36pm
10/29/2020 1:36pm
Sanded the engine and painted it. Im probably going to sand blast the head and leave it as raw metal.
cr2507354
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cr2507354 10/29/2020 1:39pm
10/29/2020 1:39pm
Are the rear shocks on 70s Yamahas rebuildable??
cr2507354
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cr2507354 10/29/2020 1:40pm
10/29/2020 1:40pm
Started putting it back together already! The frame and swing arm cleaned up nice nicely
cr2507354
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cr2507354 10/29/2020 1:42pm
10/29/2020 1:42pm
Cleaned up the forks and put new fluid in. The seals don’t leak at all so no point in rebuilding them right now. The front wheel cleaned up really nice
cr2507354
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cr2507354 10/29/2020 1:46pm
10/29/2020 1:46pm
More progress... clean up the rear wheel and mounted up a tire that I had laying around.also got the air box and some other parts cleaned up and put on the bike!
cr2507354
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cr2507354 10/29/2020 1:49pm
10/29/2020 1:49pm
Does anyone know where to get a bolt kit for a 70s Yamaha?
450exc115
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450exc115 10/30/2020 6:17am
10/30/2020 6:17am
cr2507354 wrote:
Are the rear shocks on 70s Yamahas rebuildable??
Yes. You can use a newer style seal head to replace the dated setup in those shocks. The YZ125 rear shock had a spacer in it too that you can toss and get an 1"+ or more of extra travel. The forks also have long rebound springs (Bob Hannah liked having the bike closer to the ground for better handling) that can be replaced to gain travel in the front. Yamaha tucked the front end a little on the 79 which made them handle better. Looks like you found a good deal.
1
cr2507354
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cr2507354 10/30/2020 8:50am
10/30/2020 8:50am
cr2507354 wrote:
Are the rear shocks on 70s Yamahas rebuildable??
450exc115 wrote:
Yes. You can use a newer style seal head to replace the dated setup in those shocks. The YZ125 rear shock had a spacer in it...
Yes. You can use a newer style seal head to replace the dated setup in those shocks. The YZ125 rear shock had a spacer in it too that you can toss and get an 1"+ or more of extra travel. The forks also have long rebound springs (Bob Hannah liked having the bike closer to the ground for better handling) that can be replaced to gain travel in the front. Yamaha tucked the front end a little on the 79 which made them handle better. Looks like you found a good deal.
Thanks! I’m going to do that most likely because the front suspension is a lot better with new fluid but the rear feels terrible. I haven’t had to much experience with this old of a bike but it’s been fun working on it!
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450exc115 10/30/2020 8:58am
10/30/2020 8:58am
You can do a lot to improve the function of the rear shock. I've built a few from stock to heavily modified with modern internals.

Here is a 81 I modified with fox remote reservoir and modern piston/valving.

1
cr2507354
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cr2507354 10/30/2020 9:11am
10/30/2020 9:11am
450exc115 wrote:
You can do a lot to improve the function of the rear shock. I've built a few from stock to heavily modified with modern internals. Here...
You can do a lot to improve the function of the rear shock. I've built a few from stock to heavily modified with modern internals.

Here is a 81 I modified with fox remote reservoir and modern piston/valving.

I’m going to keep an eye out on eBay for a 1981 shock if thats what will work better. Where did you get the fox reservoir?
1
cr2507354
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cr2507354 10/30/2020 9:17am
10/30/2020 9:17am
Here is one that I found just now for cheap!

Pit Row

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450exc115
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450exc115 10/30/2020 9:23am
10/30/2020 9:23am
Only 79 will work. The 80-81 are shorter as they changed the shock placement and angle. As long as the bore is good in the 79 that's the best shock for that chassis.

You can buy Fox reservoirs from spend shops for just under $100. If you want the compression adjuster that's another $130 or rob it from a street bike or atv application like I did
2
cr2507354
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cr2507354 10/30/2020 9:27am
10/30/2020 9:27am
Ohhh ok 😂 I thought the 1981 rear shock fit. It does look way shorter haha. I see what you mean now. Thanks for the help!
Ti
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Ti 10/30/2020 3:02pm
10/30/2020 3:02pm Edited Date/Time 10/30/2020 3:04pm
I do not know if you are interested in a spare engine for your bike or not??

I was trying to find an engine at our farm for the guy from New York who sent his engine [1980 YZ250] to Terry Varner in California... and having a HORRIBLE time trying to get it back. [[there is a thread here about his ordeal]]

Anyway I sent my boys into the front of one of the storage containers that is full of Yamaha's, with crates in the front [I could not fit because the motorcycles are shrunk wrapped like boats and stacked two high] to look for a 1980 YZ250 engine... they brought out a crate labeled 1980YZ. There was even a newspaper on top of the engine that had the headline "John Lennon shot"

The engine turned out to be a 1979 YZ125. I will take it apart with my boys... and if you would like I will send pictures to you.
1
cr2507354
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cr2507354 10/30/2020 4:05pm
10/30/2020 4:05pm
Ti wrote:
I do not know if you are interested in a spare engine for your bike or not?? I was trying to find an engine at our...
I do not know if you are interested in a spare engine for your bike or not??

I was trying to find an engine at our farm for the guy from New York who sent his engine [1980 YZ250] to Terry Varner in California... and having a HORRIBLE time trying to get it back. [[there is a thread here about his ordeal]]

Anyway I sent my boys into the front of one of the storage containers that is full of Yamaha's, with crates in the front [I could not fit because the motorcycles are shrunk wrapped like boats and stacked two high] to look for a 1980 YZ250 engine... they brought out a crate labeled 1980YZ. There was even a newspaper on top of the engine that had the headline "John Lennon shot"

The engine turned out to be a 1979 YZ125. I will take it apart with my boys... and if you would like I will send pictures to you.
I probably wouldn’t want to buy the whole engine but if y’all are taking it apart I would be interested in some parts from it
Ti
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Ti 10/30/2020 8:15pm
10/30/2020 8:15pm Edited Date/Time 10/30/2020 8:19pm
I was just opening the engine up to show you the condition of the internals if you wanted a spare motor to use at the races.

The storage container was sealed up in 1982 [I was four or five], but it was one of the containers our neighbor was positive the Yamaha race bikes were in.

I am not going to part the motor, I will have them box it and shrink wrap it at the marina and put it back in the container. I really wanted to find a YZ250 motor for a fellow vital member, but I do not have the time to pull all the bikes out to get to the crates in the front of this container. And I am not going to have my boys crawl under the frames of these old race bikes to get to the front again..

Have FUN with your race build..... and have the time of your life at the vintage races!!!!
1
cr2507354
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cr2507354 10/30/2020 8:18pm
10/30/2020 8:18pm
Ti wrote:
I was just opening the engine up to show you the condition of the internals if you wanted a spare motor to use at the races...
I was just opening the engine up to show you the condition of the internals if you wanted a spare motor to use at the races.

The storage container was sealed up in 1982 [I was four or five], but it was one of the containers our neighbor was positive the Yamaha race bikes were in.

I am not going to part the motor, I will have them box it and shrink wrap it at the marina and put it back in the container. I really wanted to find a YZ250 motor for a fellow vital member, but I do not have the time to pull all the bikes out to get to the crates in the front of this container. And I am not going to have my boys crawl under the frames of these old race bikes to get to the front again..

Have FUN with your race build..... and have the time of your life at the vintage races!!!!
How much for the motor?
Shawbridge Husky 11/14/2020 5:59pm
11/14/2020 5:59pm
To the OP : A clean '79 YZ250 shock would be the way to go on the cheap, same body, more travel with heavier spring and different valving I think
Suicidal_Tendencies 12/8/2020 9:21pm
12/8/2020 9:21pm
cr2507354 wrote:
More progress on the bike!! [img]https://p.vitalmx.com/photos/forums/2020/12/05/463681/s1200_8EF0E848_9082_4876_A06E_DAEF374F870C.jpg[/img]
More progress on the bike!!
Looking good!

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