1980 YZ 250

SCREAMIN62
Edited Date/Time 12/18/2020 9:52pm
Just finished this bike, just thought I'd share.



Dead of winter, gonna be months before I can ride it.
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Wandell
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Wandell 12/19/2012 6:01pm
12/19/2012 6:01pm
Looks great! Nice job!!
SCREAMIN62 12/19/2012 6:45pm
12/19/2012 6:45pm
Yep, 43mm fork upgrade with Race Tech emulators and stiffer springs.
newmann
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newmann 12/19/2012 7:11pm
12/19/2012 7:11pm
Give us a ride report and some engine specifics. My 81 model feels slow. No real low end grunt, fair midrange and little over rev. Pretty unexciting. I tried a DG pipe and now have the Pro-Form which doesn't seem to be much different in performance over the DG. Be interested to hear how yours runs.

Looks good!

The Shop

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SCREAMIN62 12/19/2012 8:24pm
12/19/2012 8:24pm Edited Date/Time 12/19/2012 8:30pm
Bought the bike in fall, it was a pretty clean unit. Only rode it for a hour or so to make sure it shifted and ran properly. It had the PFR pipe on it, boyesen reeds (toast) and what looked like a bone stock cylinder. It ran well, but certainly was no rocket but easily came on the pipe with a stab of the clutch. I've ridden a few of these bikes with various engine mods, pipes etc. I think the stock pipe works prob as well as the aftermarket ones. My friends PFR pipe is different than mine, my header is much longer than his ( strange). I know PFR makes diff pipes for some models but didn't think they did for this model. His uses o-ring at the header , mine does not. His is ported to the max and is super fast if you can keep it on the pipe (he can, I find that to be too much work).
I did replace the cylinder because I found a cracked exhaust bridge. I replaced the Boyesen reeds with a V-force set-up to try.
Found a sleeved cylinder stock bore, had the ports properly matched and flow benched ( local old mx engine guru). Asked him to keep it close to stock. Any input on the sleeved cylinder? I was reluctant at first but sure looked nice after.
I have gathered up some cylinders now for some experimentation!
I do think a bike can "feel" slow when the transition from bottom end to mid to top end is smooth. Is your bike actually slow?
Or does it just feel slow?
I also have a 465 with pipe and a lot of testing/tuning, the power is so smooth compared to any other 465 I've ridden but the bike is super fast ( only about a length behind my new 450 in drags).
Where are you at with jetting on your 250?
I know you are very knowledgeable , excuse me if I'm stating the obvious here. Look forward to your response.
xnationalwrench 12/20/2012 9:12am
12/20/2012 9:12am Edited Date/Time 12/20/2012 9:16am
newmann wrote:
Give us a ride report and some engine specifics. My 81 model feels slow. No real low end grunt, fair midrange and little over rev. Pretty...
Give us a ride report and some engine specifics. My 81 model feels slow. No real low end grunt, fair midrange and little over rev. Pretty unexciting. I tried a DG pipe and now have the Pro-Form which doesn't seem to be much different in performance over the DG. Be interested to hear how yours runs.

Looks good!
I'm not sure when the Yamaha Wrench Report came out but except for some different bore and strokes the Yamaha engines were fairly similar so check it out and get some horsepower.
project racer 12/20/2012 4:09pm
12/20/2012 4:09pm
I had a new '80 YZ250 back when. I thought it was pretty fast, even stock. Ran up front in the B class all year on it. Only the '80 CR 250 was a match for it, motor wise. On the whooped out sand tracks here, the Yamaha seemed to have an overall edge, handling, suspension, power combined.

Yamaha kind of went for the mid range type of power for 81. The 250 and 465 were much mellower than the '80 models.

They did the same thing from the '83 250 to the '84. My K model was a mid to top rocket, the 84 went for the low to mid, and signed off early.

The G model 465 was a brute.
JustPuttinAround 12/21/2012 3:02pm
12/21/2012 3:02pm
Woohoo Damn...NICE bike!

I had a Jim Felt ported jug on mine back in the day and it was a holeshot machine!
SCREAMIN62 12/22/2012 2:20pm
12/22/2012 2:20pm
Newmann, do you remember what jetting you ended up with? What fuel are you using? Looking for a baseline to start with.
newmann
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newmann 12/22/2012 2:33pm
12/22/2012 2:33pm
I'll have to dive in. That was a few years back. 38mm Sudco Mikuni. Thinking 380 or 390 main for some reason? Not sure. I'll get all pertinent info.
yzvet426
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yzvet426 12/27/2012 8:38am
12/27/2012 8:38am
It looks like you have the XYZ triple clamps but different bar mounts. What bar mounts did you use and what bend bars? I've got a 79 and I have to ride like a hunchback on it
SCREAMIN62 12/27/2012 5:11pm
12/27/2012 5:11pm
yzvet426 wrote:
It looks like you have the XYZ triple clamps but different bar mounts. What bar mounts did you use and what bend bars? I've got a...
It looks like you have the XYZ triple clamps but different bar mounts. What bar mounts did you use and what bend bars? I've got a 79 and I have to ride like a hunchback on it
Those are XYZ triples clamps correct. Bar mounts are moose ( extra long bolts for the clamps). I'm not usually into oversize bars on my vintage stuff but the bike had them on already. The bars are Vortex ( same bend as 971). I have Renthal 984s on all the of my vintage stuff ( about an inch taller than the 971 bend). I try to use all the same bend bars on all my bikes, makes it easier to adapt to on race day.
MaxPower
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MaxPower 12/28/2012 5:38pm
12/28/2012 5:38pm
project racer wrote:
I had a new '80 YZ250 back when. I thought it was pretty fast, even stock. Ran up front in the B class all year on...
I had a new '80 YZ250 back when. I thought it was pretty fast, even stock. Ran up front in the B class all year on it. Only the '80 CR 250 was a match for it, motor wise. On the whooped out sand tracks here, the Yamaha seemed to have an overall edge, handling, suspension, power combined.

Yamaha kind of went for the mid range type of power for 81. The 250 and 465 were much mellower than the '80 models.

They did the same thing from the '83 250 to the '84. My K model was a mid to top rocket, the 84 went for the low to mid, and signed off early.

The G model 465 was a brute.
my opinion of the suspension of that bike is the polar opposite. Stock or revalved, I thought the mono shock was horrific. Not that I didn't have find on that bike. I just don't I know if I could say something nice about the shock other than it went up and down. I would still own and race one today in a heartbeat if I had the chance.
1
rob.boucher.547 1/17/2013 2:56pm
1/17/2013 2:56pm
Cool bike,

The trick to get the ultimate look on resto racer's and to really get the bike to stand out
Is hand machined bolts,washers, exhaust mounts, all out of titanium, 17-4 SS, and aluminum.

I make all my bolts, hardware, bits from billet
ledger
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ledger 1/18/2013 8:48pm
1/18/2013 8:48pm
This bike just got my attention and in a huge positive way.You did a fantastic job.This bike got the job done in it's day and looked good doing it,all the way to the checkered flag.
dave.bonz.9
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dave.bonz.9 1/29/2013 7:03pm
1/29/2013 7:03pm
# 1 that a sweet ass yz 250 .. # 2 I had a 78 & 79 at the same time,,,and had a 1980 yz 250 a few years later and loved all 3 bikes big time.. I'm a big guy 6 3" 248 and these bikes riped me around like i was a 80 lb -er not kidding ,, these bikes hull ASS !! I day i went out to this place to ride my bike ( texas canyon ) in so - cal after going thu the motor and few other things as i pulled up there was a few other guys there with 88 - 90 cr 250's looking and laughing at my old and slow YZ ( as thy thought ) ,,lmao. after about 5 mins of warming it up i got on it and putted over to the straight away that's about 3/4 to a mil long ... right as i pulled out on the straight away i opened the BAD BOY UP !!! both of the guy's were coming up on both sides of me to show me HOW SLOW MY OLD NASTY YZ WAS !!!! lmao again all the way down to the other side of the riding park,, As i went into 2ed,,,3ed,,,4th ,,,,,5th ,,,,and then 6th i was waiting to see both cr's come flying by me,,, But about at the qt mil mark when i looked back at the CR"S there were so far BACK IN MY DUST !!!! that i let up turned around to go back and chk on them ( no lie ) The only thing i did to this bike was put on a one more tooth front sprocket and new piston in it,,The sprocket added about 6 mph on top and with the 6 speed thy both got SMOKED !!!! GOOD . When i pulled back into the docking area 10 to 15 mins later both bikes and trucks were GONE .. and i know why that was,,,lol
ledger
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ledger 1/29/2013 8:13pm
1/29/2013 8:13pm
Oh my gosh!!! That is my dream machine.Excellant job,I raced that bike back in the day.CONGRAT"S TO YOU.
Zook La Douche 2/2/2013 6:15pm
2/2/2013 6:15pm
My favorite bike of all time. 1980 was a good year for YZ-125 and 250. Great looking job!!!

Pit Row

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rob.boucher.547 2/4/2013 4:04pm
2/4/2013 4:04pm
Here is the 1980 YZ250G I rebuilt about 5 years ago, I have a few more trick parts that will be installed someday


3
Frog #1
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Frog #1 2/4/2013 7:11pm
2/4/2013 7:11pm Edited Date/Time 2/4/2013 7:12pm
1979 KX250 anybody! Made to looks like 1978 works SR250!
2
SCREAMIN62 2/4/2013 8:13pm
2/4/2013 8:13pm
rob.boucher.547 wrote:
Here is the 1980 YZ250G I rebuilt about 5 years ago, I have a few more trick parts that will be installed someday [img]https://p.vitalmx.com/photos/forums/2013/02/04/1980_yz250g_002_24909.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2013/02/04/1980_yz250g_011_788125.jpg[/img]
Here is the 1980 YZ250G I rebuilt about 5 years ago, I have a few more trick parts that will be installed someday


Nice bike! Give some details, suspension, motor etc.
MaxPower
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MaxPower 2/4/2013 11:03pm
2/4/2013 11:03pm
rob.boucher.547 wrote:
Here is the 1980 YZ250G I rebuilt about 5 years ago, I have a few more trick parts that will be installed someday [img]https://p.vitalmx.com/photos/forums/2013/02/04/1980_yz250g_002_24909.jpg[/img] [img]https://p.vitalmx.com/photos/forums/2013/02/04/1980_yz250g_011_788125.jpg[/img]
Here is the 1980 YZ250G I rebuilt about 5 years ago, I have a few more trick parts that will be installed someday


Little things like the tony d fender and KYB stickies make that bike look just right
rob.boucher.547 2/7/2013 3:19pm
2/7/2013 3:19pm Edited Date/Time 2/7/2013 3:28pm
The forks are hand machined, also replaced most of the fasteners with hand machined ti, aluminum drilled washers,bushings
On the fuel tank. The rear shock is a white bros modded, dual spring set-up about a 1.5 longer than stock. Ported cylinder

I am currently machining a few billet filled reservoir sets for the bikes with large I.D. braided hose

I cannot remember all the tricks on the bike, brand new Oem clutch basket( found at a car dealer on eBay) that
Had a huge stock of 80-81 yz parts, they had a listing on eBay stating old Yamaha stock found in back room
Email with needs
Bought a number of parts of cheap
The swing arm has been modified(if you can tell, or have a guess,) post
MaxPower
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MaxPower 2/8/2013 4:59am
2/8/2013 4:59am
what do you mean machined with the front forks? Did you chuck up the stock forks and put a finish on them to look factory or did you make them? Because they look works to me
1.5 inches longer at the shock or the seat? Because if its at the shock , that is a long YZ shock
I cant tell what is done to the swing arm.
It would be bad ass if someone made an aluminum tank for these bikes. Ones that cost less than 1000 dollars I mean
SCREAMIN62 2/8/2013 9:27am
2/8/2013 9:27am
Hey Rob, what's the vintage race scene like near Minneapolis. Always looking for a close place to race (within 8 hrs).
It's amazing how many nos parts are still available either from dealers or ebay. If you have any engine parts, I would be interested for sure.
Can't tell whats been done to your swingarm either, fill us in!
yamadogyz
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yamadogyz 2/8/2013 9:58am
2/8/2013 9:58am
that thing is sick. wheres its next destination, loroccos?
project racer 2/8/2013 12:52pm
2/8/2013 12:52pm Edited Date/Time 2/8/2013 12:53pm
If lengthening was the swing arm mod, I believe the 465G model swingarms were about an inch longer than the 250's, and bolt right on. Popular mod back then.
rob.boucher.547 2/9/2013 8:10am
2/9/2013 8:10am
The 80-81 Yamaha YZ models were the best production bikes you could buy. They were high quality, very durable, trick looking
And great all around performers.
I own a 81 full floater zook Modded 465- fantastic bike, Suzuki quality has always been a step down- but if you watch everything
Closely, they can last, I can list the poor items but that is another story.

Besides the basic mods, the best thing a person can do to the 80-81 YZ models is shed some weight.
An easy 10 lb reduction is attainable
Remove all the steel spacers, heavy hardware, seat brackets, axle spacers,internal hub spacers, kick stand mount,
Steel kicker(almost 5 lbs), replace steel washers, shock spring collar
Replace the bolts with aluminum,Ti bolts
Brake stay, steel bars
rob.boucher.547 2/9/2013 8:14am
2/9/2013 8:14am
MIDWEST VMX is the local vintage group .

Also the local VJMC club is huge is the twin cities here, we have the largest Vintage show in the Midwest in June.

A large show at the Minnesota state fairgrounds, last summer we had huge turnout again
Shawbridge Husky 12/4/2014 4:20pm
12/4/2014 4:20pm Edited Date/Time 12/5/2014 7:39am
NICE bikes Screaming and Rob Boucher, drool ! Rob Boucher when you say hand machined forks you mean to say you took a skim cut off the OD on the lower fork legs ? If so I'll do same to my CR250 forks. Wish you were closer to mentor me.. I can only hope to get close to the same look on my upcoming '80 CR125 project. A red Tony D fender will be on mine for sure, love that old school unique rounded look !
Hugh

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