81 yz250 forks/front brake question

swatdoc
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swatdoc
Edited Date/Time 11/10/2014 7:46pm
Hey guys in looking at 81 250's and I see some with dual front brake arms and some with single arms. What was standard? And did all the 81's have 43mm forks?
Thanks
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newmann
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newmann 8/4/2014 4:35am
8/4/2014 4:35am
The dual actuated brakes came off of the YZ465. Backing plate is a direct swap.
C2C
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C2C 8/4/2014 2:10pm
8/4/2014 2:10pm
81 250's and 465's have 43mm forks. 125's have 38 mm...
newmann
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newmann 8/4/2014 2:19pm
8/4/2014 2:19pm Edited Date/Time 8/4/2014 2:20pm
C2C wrote:
81 250's and 465's have 43mm forks. 125's have 38 mm...
Long time, no posts. What's up?? Anything exciting?
swatdoc
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swatdoc 8/4/2014 2:31pm
8/4/2014 2:31pm
Thanks guys - I'm buying an 81 and am a little confused on a couple things. I think you guys cleared up the fork/brake issue for me.

It seems there are 2 models of the 81's - an H and a G model. First, what are the differences? And second, can you tell from the VIV which model - the vin for this bike is 4V2002133

thanks guys

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C2C
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C2C 8/4/2014 2:32pm
8/4/2014 2:32pm
Hello Jo, I come here every day but not connected..
C2C
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C2C 8/4/2014 2:33pm
8/4/2014 2:33pm Edited Date/Time 8/4/2014 2:35pm
4V2 is H 125. 81 model.... '4V3 is 250 H. 81 model. 3R4 is G. 80 model
newmann
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newmann 8/4/2014 2:35pm
8/4/2014 2:35pm
I think the 80 model 250 had 38mm forks, not sure about the 465.
C2C
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C2C 8/4/2014 2:38pm
8/4/2014 2:38pm
yes Jo, the 1980 465 have a 38 mm fork.
swatdoc
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swatdoc 8/4/2014 2:41pm
8/4/2014 2:41pm
huh that is weird - is it possible they stuck a 250 motor in a 125 frame?

here's a link to the bike - what do you guys think? is this some kind of frankenbike with a huge parts miss-mash?
They did tell me it needs a new cdi and stator, which is fine, that's no big deal to replace, but this vin thing worries me

http://www.ebay.com/itm/Yamaha-YZ-1981-Yamaha-YZ-250-Vintage-Restored-/…
newmann
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newmann 8/4/2014 2:57pm
8/4/2014 2:57pm
No, the 125 was a completely different bike. The 250 and 465's were basically the same chassis.
swatdoc
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swatdoc 8/4/2014 3:29pm
8/4/2014 3:29pm
in one of the ebay pics, a close up of the cylinder shows a part number of 4V3 - so that matches up with an 81 250H model - not sure why the farm would be different though.

Can you guys point me in a direction to find out the differences between the H and G models?

thanks
newmann
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newmann 8/4/2014 3:48pm
8/4/2014 3:48pm
1980 YZ250G model was a 6 speed gear box I do believe. Look for any old magazine test articles on the 81, they will usually point out the upgrades.

Ask me about the differences in 74-78 CR125's though.....Smile
swatdoc
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swatdoc 8/4/2014 4:02pm
8/4/2014 4:02pm
ok Newmann I think the lightbulb finally went on for me! Although I have seen 81's listed as both G and H, It would seem like the G was actually the designation for the 1980 model, and H was the 81. Kinda making sense now. Although the frame vin is a little funny, at least the motor seems to have the correct designation. Feeling a little better about the bike now.

My first bike was a 75 CR125 - loved it. Then got a 77 i believe it was, before graduating to my beloved 78 CR250R.











Ardfarkl
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Ardfarkl 8/5/2014 7:05am
8/5/2014 7:05am
C2C wrote:
81 250's and 465's have 43mm forks. 125's have 38 mm...
I hgave an '81 YZ 250 and it has 38mm forks, not 43mm.
newmann
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newmann 8/5/2014 8:18am
8/5/2014 8:18am
I have an81 YZ250 and it has 46mm forks.Smile



Ard, somethings up there buddy. Someone swap an 80 front end onto yours?

Ardfarkl
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Ardfarkl 8/5/2014 4:29pm
8/5/2014 4:29pm Edited Date/Time 8/5/2014 4:30pm
My apologies. Local know it all gave me incorrect info as he was trying to sell me a set of 43mms! Thanks guys!
swatdoc
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swatdoc 8/5/2014 5:12pm
8/5/2014 5:12pm
Love your YZ Newmann. I'll be on the hunt to find some trick stuff for mine now!

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rob.boucher.547 8/6/2014 9:17am
8/6/2014 9:17am Edited Date/Time 8/6/2014 11:07am
The dual cam set-up was standard on the 80 465g
an option on the 250g for 1980
My 1980 250 G had the dual set-up from the dealer
The 1980 250G 6-8 lbs lighter based on the magazine tests
and faster than all the 81 jap bikes tested in the magazine
shootouts that year
C2C
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C2C 8/6/2014 1:15pm
8/6/2014 1:15pm Edited Date/Time 8/6/2014 1:18pm
I'm with you Rob, the G is a good bike but the 6 speed gear box is made of glass...
I have a G ported cylinder with additionnal boosters on my H : the bike rips !!!!
newmann
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newmann 8/6/2014 2:29pm
8/6/2014 2:29pm
C2C wrote:
I'm with you Rob, the G is a good bike but the 6 speed gear box is made of glass... I have a G ported cylinder...
I'm with you Rob, the G is a good bike but the 6 speed gear box is made of glass...
I have a G ported cylinder with additionnal boosters on my H : the bike rips !!!!
Maybe that's what mine needs. The 81 is a turd. Think I have some death spooge leaking from my ignition. I may drop a PVL in mine since I have one in everything else.Laughing

Going to ditch the boost bottle as well.
project racer 8/6/2014 8:32pm
8/6/2014 8:32pm
Fragged the gearbox in my new 250G after owning it about four months. Fast bike, though. The 465G trans were shit too.
barkhard696
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barkhard696 11/9/2014 7:58am
11/9/2014 7:58am
I believe Rick Sieman or Jody Weisel said the '80 YZ250 was the best YZ in terms of performance gap over competitors same year models. Everyone seemed to love the suspension, the Monocross reaching the pinnacle of development before the linkage suspensions came along, coupled with the flexibility of the 6 speed. Yamaha is a big parts recycle/trickle down company-- didn't they use the '80 YZ250 bottom end in the '83 IT250?

It's too bad the transmissions of those years were so fragile. Yamaha still gets a gold star in terms of parts availability compared to some of the other brands.
Cancerman
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Cancerman 11/9/2014 9:52pm
11/9/2014 9:52pm
project racer wrote:
Fragged the gearbox in my new 250G after owning it about four months. Fast bike, though. The 465G trans were shit too.
I raced both the 1980 YZ 250 & 465 back in 1980. Both were purchased new> Never had a DNF, no seizures, no tranny issues at all. Moto and GP/Hare scrambles. When I got out of the service, I bought a used G model 250 in So Cal, raced it until 1985 when I got my first new Honda CR. I raced desert as well in So Cal, never DNF'd, no tranny issues. I'm restoring a 250 G right now, from the frame up. These were good bikes in their day. I'll do vintage races with this one. I'd still like to find a 465 though. I loved mine.Cool
captmoto
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captmoto 11/9/2014 11:28pm
11/9/2014 11:28pm
I took a ride on a friends 250G. I bought one the next day. I was a die hard Suzuki guy back then.
I never broke my G model 250. Never had any mechanical problems.
I recently crushed a shift drum on my 465 but was easily replaced from Ebay. Shifter forks seem soft but haven't fragged one yet.
Prairieboy43
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Prairieboy43 11/10/2014 7:46pm
11/10/2014 7:46pm
newmann wrote:
I have an81 YZ250 and it has 46mm forks.:) [img]https://p.vitalmx.com/photos/forums/2014/08/05/61596/s1200_darrick1.jpg[/img] Ard, somethings up there buddy. Someone swap an 80 front end onto yours?
I have an81 YZ250 and it has 46mm forks.Smile



Ard, somethings up there buddy. Someone swap an 80 front end onto yours?

46mm forks? What's the story? Kx250 forks?
colinac34
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colinac34 3/27/2017 9:29am
3/27/2017 9:29am
Does anyone have a pvl ignition system installed on their 1981 yz 250 h. If so could you tell me what your B.T.D.C measurement is.

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