More power out of 1980 YZ 125?????

berniepiet
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berniepiet
Edited Date/Time 12/20/2018 11:32am
Have a nice, very stock , 1980 yz 125 G, that I would like to race next year. Am going to put 1980 YZ 250 or 465 rear shock spring on and probably bolt on some 1980 YZ 250 forks. So I am set with the suspension.

Anybody have any tips on getting a few more ponies out of the engine? I have ridden some 82/83 Suzukis that pull like my KTM 150. Don't know that much about the air cooled engines though. Rob Boucher , Newman ? Any tips?
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Brett Campbell 7/7/2014 7:23am
7/7/2014 7:23am Edited Date/Time 7/7/2014 10:03am
If you can, get your hands on the old Yamaha wrench reports for this year, they have some good hop up tips.
Joe_Stricklin 7/7/2014 7:34am
7/7/2014 7:34am
Hey Ziggy

Finally sold mine about a year ago. Never could get it jetted right. Went though about three cylinders. LOL I think I still have a couple.

I got it jetted pretty close when I sold it but man I really had run that thing WFO or it would not put out much power. But when it hit the front end would come off the ground.

Handling was great like riding a large mini or a mountain bike. I did lots of research and I think I still have some of the stuff I found. I got Eric Gorr do the cylinder I ended up with. I think I have some Boyesen reeds too. I can make a good deal for ya if you show up at a race that is.

C ya
berniepiet
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berniepiet 7/7/2014 9:01am
7/7/2014 9:01am Edited Date/Time 7/7/2014 9:02am
Joe_Stricklin wrote:
Hey Ziggy Finally sold mine about a year ago. Never could get it jetted right. Went though about three cylinders. LOL I think I still have...
Hey Ziggy

Finally sold mine about a year ago. Never could get it jetted right. Went though about three cylinders. LOL I think I still have a couple.

I got it jetted pretty close when I sold it but man I really had run that thing WFO or it would not put out much power. But when it hit the front end would come off the ground.

Handling was great like riding a large mini or a mountain bike. I did lots of research and I think I still have some of the stuff I found. I got Eric Gorr do the cylinder I ended up with. I think I have some Boyesen reeds too. I can make a good deal for ya if you show up at a race that is.

C ya
Sounds good Joe. Who ended up buying it?

The Shop

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berniepiet
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berniepiet 7/7/2014 9:03am
7/7/2014 9:03am
Brett Campbell wrote:
If you can, get your hands on the old Yamaha wrench reports for this year, they have some good hop up tips.
Thanks Brett. Do you race SEVMX with us?
Brett Campbell 7/7/2014 9:36am
7/7/2014 9:36am
Brett Campbell wrote:
If you can, get your hands on the old Yamaha wrench reports for this year, they have some good hop up tips.
berniepiet wrote:
Thanks Brett. Do you race SEVMX with us?
No Bernie. I have not raced since the late 80's. I mostly ride here at one of the local tracks.
Joe_Stricklin 7/7/2014 10:01am
7/7/2014 10:01am
East Coast Vintage bought it. Not sure who wound up with it.
GIwasB4
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GIwasB4 7/7/2014 10:52am
7/7/2014 10:52am
Brett Campbell wrote:
If you can, get your hands on the old Yamaha wrench reports for this year, they have some good hop up tips.
This.
If you relieve the exhaust port bridge it greatly improves the cylinder's longevity. It's covered in the wrench report.
For more power, porting, pipe and either the stock carb bored, or put on the 1981 YZ125 carb.
Joe_Stricklin 7/7/2014 11:51am
7/7/2014 11:51am
Also I have a brand new uni air filter. But i highly recommend getting a filter for a 81 CR125 (i think twin air makes it) that has a molded on boot. You have to modify the air box for it to work but I had lots problems with my air box from warping and just not sealing properly and it does not need a cage. Need to add some type of support for the backside of the carb though. If you don't I would take the whole air box apart and reseal the whole thing really good.

This was the cause of one rebore...lol
berniepiet
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berniepiet 7/7/2014 11:56am
7/7/2014 11:56am
Brett Campbell wrote:
If you can, get your hands on the old Yamaha wrench reports for this year, they have some good hop up tips.
GIwasB4 wrote:
This. If you relieve the exhaust port bridge it greatly improves the cylinder's longevity. It's covered in the wrench report. For more power, porting, pipe and...
This.
If you relieve the exhaust port bridge it greatly improves the cylinder's longevity. It's covered in the wrench report.
For more power, porting, pipe and either the stock carb bored, or put on the 1981 YZ125 carb.
Thanks! Any pipe that you recommend? I have a flat slide Kiehn from a 1986 CR125. Would that be too much carb?
berniepiet
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berniepiet 7/7/2014 11:56am
7/7/2014 11:56am
Joe_Stricklin wrote:
Also I have a brand new uni air filter. But i highly recommend getting a filter for a 81 CR125 (i think twin air makes it)...
Also I have a brand new uni air filter. But i highly recommend getting a filter for a 81 CR125 (i think twin air makes it) that has a molded on boot. You have to modify the air box for it to work but I had lots problems with my air box from warping and just not sealing properly and it does not need a cage. Need to add some type of support for the backside of the carb though. If you don't I would take the whole air box apart and reseal the whole thing really good.

This was the cause of one rebore...lol
Thanks Joe, I will be in touch
GIwasB4
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GIwasB4 7/9/2014 12:41pm
7/9/2014 12:41pm
berniepiet wrote:
Thanks! Any pipe that you recommend? I have a flat slide Kiehn from a 1986 CR125. Would that be too much carb?
DG pipe, if you can find one. Pro-Form makes one, never ran it. Jemco pipe (pictured) adds nice mid-range hit all the way to the top.


The CR carb would be all over the place jetting wise. The 1981 YZ125 carb is plug and play and should only need fine tuning and makes the biggest difference.

berniepiet
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berniepiet 7/9/2014 1:32pm
7/9/2014 1:32pm
GIwasB4 wrote:
DG pipe, if you can find one. Pro-Form makes one, never ran it. Jemco pipe (pictured) adds nice mid-range hit all the way to the top...
DG pipe, if you can find one. Pro-Form makes one, never ran it. Jemco pipe (pictured) adds nice mid-range hit all the way to the top.


The CR carb would be all over the place jetting wise. The 1981 YZ125 carb is plug and play and should only need fine tuning and makes the biggest difference.

Thanks for the info. I appreciate it.

How would I tell the difference between the 1980 and 1981 carb?

Do you have any ideas on which wide foot pegs work best on the 1980 yz 125?

That pipe wouldn't happen to be for sale would it?
kelroy_leon
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kelroy_leon 7/9/2014 2:09pm
7/9/2014 2:09pm
The 82/83 Suzuki was a power valve engine. The OWO1 was a power valve air cooled Yamaha if I recall?
GIwasB4
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GIwasB4 7/9/2014 3:29pm
7/9/2014 3:29pm
1980 32mm carb has straight pull up choke and 3R3 stamped on front.



1981 34mm carb has push down lever chock with 4V2 stamped on it.









Not for sale.

berniepiet
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berniepiet 7/9/2014 7:39pm
7/9/2014 7:39pm
GIwasB4 wrote:
1980 32mm carb has straight pull up choke and 3R3 stamped on front. [img]https://p.vitalmx.com/photos/forums/2014/07/09/59005/s1200_1980_YZ_3R3_Carb.jpg[/img] 1981 34mm carb has push down lever chock with 4V2 stamped on...
1980 32mm carb has straight pull up choke and 3R3 stamped on front.



1981 34mm carb has push down lever chock with 4V2 stamped on it.









Not for sale.

Thanks! I talked to Jon at Jemco today. Super nice guy
GIwasB4
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GIwasB4 7/10/2014 1:23am
7/10/2014 1:23am
berniepiet wrote:
Thanks! I talked to Jon at Jemco today. Super nice guy
Sent you a PM
C2C
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C2C 8/4/2014 2:28pm
8/4/2014 2:28pm


A good friend of mine is making those beautiful hydroformed pipes, more power, more rpm but expensive...



Pit Row

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Shawbridge Husky 11/27/2014 3:40pm
11/27/2014 3:40pm Edited Date/Time 11/27/2014 3:57pm
Bump for a cool thread, going to look over the H tomorrow night. If I buy it's going air cooled, still unsure about a 125 or 175 cylinder though.

Anyone know these guys, sees like a solid company to deal with :

http://ledperformanceengines.com/index.htm
Dick Trickle 11/27/2014 6:16pm
11/27/2014 6:16pm
I know Jemco makes a nice cone pipe for these bikes. Give Jon Easton at call at Jon Easton Manufacturing Company. I have one of his cone pipes for my 1983 yz125K. Here are some pics below...


YZ125G cone pipe by Jemco.


YZ125K cone pipe by Jemco

berniepiet
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berniepiet 11/27/2014 6:41pm
11/27/2014 6:41pm
Thanks!!
MaxPower
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MaxPower 11/28/2014 3:57pm
11/28/2014 3:57pm
kelroy_leon wrote:
The 82/83 Suzuki was a power valve engine. The OWO1 was a power valve air cooled Yamaha if I recall?
No they weren't. They moved the reed block to the back of the cylinder instead of in the cases but they did not have a power valve for 2 or 3 more years.
kelroy_leon
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kelroy_leon 11/28/2014 5:05pm
11/28/2014 5:05pm
Thank you for the clarification, I was mistaken.
#214
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#214 12/20/2018 11:32am
12/20/2018 11:32am
C2C wrote:
[img]https://p.vitalmx.com/photos/forums/2014/08/04/61494/s1200_1980_yz_125.jpg[/img] A good friend of mine is making those beautiful hydroformed pipes, more power, more rpm but expensive... [img]https://p.vitalmx.com/photos/forums/2014/08/04/61495/s1200_yz_125_83_3.jpg[/img]


A good friend of mine is making those beautiful hydroformed pipes, more power, more rpm but expensive...



C2C do you have a contact for these pipes?

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