1981 YZ125H modified vintage racer

5/16/2014 10:27am
All balls, Moose sell complete fork rebuild kits, bushings(upper, lower, ) bottom(dampner copper washers) drain gaskets
seal spring clips for all the 38-43 kyb models
I just purchased a kit on ebay for 23.00 with free
shipping, and installed it on a set of 43mm forks
All the same for 43 from 81-86 plus kyb
MaxPower
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5/16/2014 2:32pm
I hadn't noticed when I first looked at your 125 that you made tthe trick brake pedal. That looks pretty factory there Rob Boucher
DirtDgr
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Lakeport, CA US
5/18/2014 8:39am Edited Date/Time 5/20/2014 6:50am
Just picked up one for $500 in pretty damn good shape except for the water cooler seal. Will get that fixed up and turn it into a racer for my son.

Will not be anywhere close to the one here but I'm just stoked because I have all three sizes now. 81-125cc, 81-250cc, 80-465cc.

I will line them up at the races and get to feel like those rich kids did back in the day!



1

The Shop

11/17/2014 7:57am
Came across one locally for 300, missing stator. Is this something readily available ? I'll go take a look close up Friday night for shits and giggles.
Tuck812
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Fallon, NV US
11/17/2014 9:03am
rear brake plate after machining, bushings installed, billet axle cover, ready to assemble[img]https://p.vitalmx.com/photos/forums/2013/11/19/36850/s1200_image.jpg[/img]
rear brake plate after machining, bushings installed, billet axle cover, ready to assemble
What finish was used on your hubs ? they look awesome
MaxPower
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11/17/2014 6:00pm
Came across one locally for 300, missing stator. Is this something readily available ? I'll go take a look close up Friday night for shits and...
Came across one locally for 300, missing stator. Is this something readily available ? I'll go take a look close up Friday night for shits and giggles.
You will be able to come up with something .Finding a stator for that old YZ is a lot easier than making a swingarm.
barkhard696
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Houston, TX US
11/17/2014 6:31pm
>I hadn't noticed when I first looked at your 125 that you made tthe trick brake pedal. That looks pretty factory there Rob Boucher

+1 Rob is without a doubt one of the best machinists I have seen in our hobby. No crazy powder coatings, no bling... Just great engineering, well-executed. "God is in the details," as a famous architect once said. Steve D is up there also.

So Rob, have we pumped your head up to the size of a balloon yet?

Mike P.
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11/17/2014 7:32pm
Not sure I follow your logic on the 43mm forks being a weight issue on 80 YZ125. I race my bikes and I can tell you, when I jump I jump big and with full Race Tech suspension (to include hard anodized forks and a fully built Race Tech Shock (much lighter than the stock shock), I have had no issues with weight. Here are a couple of photos. What's not seen in these photos are the billet triple clamps I have since added. I would never ever consider running a set of 38mm forks on this bike (way too much travel…would be like riding on a set of springs with nothing to hold you up).








1
11/18/2014 7:25am
Came across one locally for 300, missing stator. Is this something readily available ? I'll go take a look close up Friday night for shits and...
Came across one locally for 300, missing stator. Is this something readily available ? I'll go take a look close up Friday night for shits and giggles.
MaxPower wrote:
You will be able to come up with something .Finding a stator for that old YZ is a lot easier than making a swingarm.
hehe, yep doing a stator is easier I admit ! I'll go look at the YZ125H Friday night, good news is it has a title !
In socialist quebec you need an off road plate to even trailer the thing.
Any untitled bike can be seized and impounded here.
Ah the joys of french québec and big government.
For the CR I will have to get creative to put a plate on it.

Rob Boucher is a pro machinist, being in the trade myself I can see his attention to detail and
knowledge in materials and their heat treatment. You on the Practical Machinist Forum Rob ?
11/20/2014 4:00pm
Question, anyone retrofit an H back to an air cooled G cylinder ?
I'm going to look the aforementioned bike over tomorrow evening and may very well end up purchasing it.
I'd prefer to run air cooled bikes and would think this would be an easy mod while benefiting from
the H's rolling chassis upgrades. Getting rid of the high CG rad and piping I could put a big 43mm front end
on it. The swingarm is longer already compared to the G so it would balance out.

So now I end up with an '80 CR125R and an '80-'81 YZ125H !

So much for simplification, but I just love the yellow and the good memories I had as a kid :


Mike P.
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11/20/2014 5:33pm
It's certainly up to you but for me that seems like a lot of work as the differences between the G & H aren't really that great. I simply do the 43mm fork (which the G nor H had), look for an H model swing arm (I found one on ebay for $50.00), get the H model throttle and you should be good to go. Also, i believe the G motor will slip into the H model frame. Take a look at my forum called "1980 Yamaha YZ175" as my bike has all those mods and they are race tested. Mike
11/29/2014 12:59pm
My VIN is 4V2-002818 where produced ?
How can I check it?
SRP33
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Shelton, CT US
11/30/2014 8:02pm
[img]https://p.vitalmx.com/photos/forums/2013/07/16/27229/s1200_image.jpg[/img]
That bike is beautiful. I have one also, what did you do for the seals in the frame for the water lines ?
12/1/2014 4:56am
My frame did not have rust issues
I remanufactured the steering stem, by sleeving the seal area's with a bronze sleeves.
See above post's

Thanks
Robert
AHRMA361
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Fantasy
232nd
12/2/2014 6:27am
Probably a decent parts bike for $150.

That is actually a 1979 "F" model.
12/2/2014 7:44am Edited Date/Time 12/2/2014 7:44am
You guys in the US have all the deals ! Up here they are few and far between.
12/13/2014 8:05am Edited Date/Time 12/13/2014 8:07am
Purchased the YZ125H last night Rob ! I got an extra complete motor and will be PM'ing you on some steering head questions later today. Once stripped down I now better appreciate it, nice well built little bike ! Totally different than my YZ125F of the past though. I'll stay water cooled after all but will really shoot for a custom 175 IT center port barrel / head retro-fit with custom water jacket on cylinder. The 38 mm forks on the front end will stay, they are up to the task as you say, if it were 36 mm they would be swapped out, 38 will work fine with some mods front and back.
swatdoc
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Temecula, CA US
12/13/2014 9:24pm
Hi Rob do any of the '81 125 parts that made interchange with the 250's? I have an 81 250 that I'd like to start making a little lighter.
thanks
John
12/14/2014 9:02am
Actually i am in the shop now, working on the tooling, and machining billet parts for the 80-81 YZ models

complete fuel tank and side panel, airbox mount bushings
exhaust hangers, both billet, and die stamped aluminum mounts
with injection molded rubber inserts, and drilled shoulder bushings
really nice stuff,

Also ti bolts and 17-4 stainless very small hand made numbers enough for
my bikes , maybe a few for sale
and that is it
swatdoc
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Location
Temecula, CA US
12/14/2014 5:15pm
OK keep me posted Rob. Let me know when you have stuff available. Do you plan on making any more of the spacers that go inside the hubs?
12/15/2014 7:44am
Hi Rob, question, I can get a 1983 CR250 rear shock with reservoir locally. Would it be worthwhile getting it to canabalize the rear rebound adjust. I have read of people doing this and there is even one for sale on ebay presently.
12/15/2014 3:42pm
Hi Rob, been trying to send you a PM. Looks like that option is not activated in your profile.

My question was on steering stem disassembly as well as deleting the water cooling.
I'm going IT175 air cooled after all on the H

That and what type titanium you are using and if there is any heat treatment involved ?
I have zero experience with the stuff. I'll be looking into dry film coating as well, another
area that is unknown to me. Do you have any recommendations and baking
procedures for as well ?

I'll need to pick yours brains on the 17-4 stainless as well. What would you recommend
for hollow wheel axles ?

My field is tool and die, machinery repair is done in house for our own needs so I
don't have as much exposure to it as you do. I would send you link to me shop but I can't PM you..

Sorry to be asking so much, I have a lot to learn in a short amount of time.
Want to make a couple meets or races summer '15

Hugh
12/19/2014 2:45pm Edited Date/Time 12/19/2014 2:54pm
You can build the bike you want
But i would make sure the 81 H base gasket matches whatever IT cylinder base gasket

The 1980 YZ125 engine was the base for the IT 175/200, and YZ100's after 81
but the 81 YZ 125 was different, left case, waterpump, centerport

Before you build a time consuming Frankenbike, you should build a nice 81 125 H
great bikes, parts and faster than a it175
easy to have ready for next season

In 81 when Magoo purchased his own bikes, he chose the 81 YZ125, and he did not have
and DNF bike problem with the YZ
mid season he was given RM's

And Bob hanah's bike OW40 had 38mm forks
1
craigmac215
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Location
Cambridge, ON CA
12/19/2014 8:19pm
Actually i am in the shop now, working on the tooling, and machining billet parts for the 80-81 YZ models complete fuel tank and side panel...
Actually i am in the shop now, working on the tooling, and machining billet parts for the 80-81 YZ models

complete fuel tank and side panel, airbox mount bushings
exhaust hangers, both billet, and die stamped aluminum mounts
with injection molded rubber inserts, and drilled shoulder bushings
really nice stuff,

Also ti bolts and 17-4 stainless very small hand made numbers enough for
my bikes , maybe a few for sale
and that is it
Rob,
If you have any of your hand made parts for sale I would be interested (1980 YZ125)
Let me know.
Craig
12/20/2014 11:03am
Went to my parts place last night, a 100, 125 and 175G bases to chose from, but some are in rough shape.
Getting a better handle on this now. Thanks Rob, all good points.



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