1986 Yamaha YZ250S

Ove
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137
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NO
3/29/2018 10:25am Edited Date/Time 1/8/2019 6:47pm
Got a basket case bike that I have as my winter project.
Was one almost complete bike and a couple of engines and a frame when I got it.
This is what I started with:







Tore it down and got the frame cleaned up, welded a few cracks and painted:



Rebuild began, all bearings etc replaced.
Öhlins shock rebuilt
Spokes etc replated
Wheels rebuilt
Some photos of the process:





















Engine getting new bearings, and overhaul of the crank.
Transmission was good
Doing some porting to the cylinder after reading Eric Gorr's book















The bike as it sits now.
It will be a Broc Glover "replica"
Since it's near impossible to get any parts, exhaust etc to do a proper replica, I will build it to look like Glover's 86 bike.





3
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nicko-31
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NY US
3/29/2018 10:53am
Nice, very nice. I didn't know Yamaha went to standard spokes in 86.
Ove
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137
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3/29/2018 11:13am
nicko-31 wrote:
Nice, very nice. I didn't know Yamaha went to standard spokes in 86.
Thanks!

The rear spokes are Z-spokes, and a first time dealing with that for me.
Front spokes are more like standard spokes
nicko-31
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3/29/2018 12:11pm
Don't let the Z spokes scare you, there actually easer to work with than standard spokes. The cylinder pic that you show of the intake side is the same extra left side boost port Eric added to one of my 85 125 YZ cyclinder also. It really cured what I believe was probably the slowest 125 in 84/85.
Ove
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3/29/2018 12:51pm
nicko-31 wrote:
Don't let the Z spokes scare you, there actually easer to work with than standard spokes. The cylinder pic that you show of the intake side...
Don't let the Z spokes scare you, there actually easer to work with than standard spokes. The cylinder pic that you show of the intake side is the same extra left side boost port Eric added to one of my 85 125 YZ cyclinder also. It really cured what I believe was probably the slowest 125 in 84/85.
Yes, I got the hang of it after a while, and rebuilding the wheel with Z-spokes was actually a cool experience. Took me some tries to sort out the order the spokes had to be installed into the hub.
Sweet, nice to know that Eric's advice works that good.

The Shop

PJRAUS
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AU
3/29/2018 2:51pm
Beautiful work!
I had both the 250 and 125 brand new that year...I loved those bikes..
PJRAUS
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3/29/2018 11:44pm


I loved mine, that was me on the 250 at the Mildura supercross in 1986
2
Ove
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137
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NO
3/30/2018 1:12am
PJRAUS wrote:
Beautiful work!
I had both the 250 and 125 brand new that year...I loved those bikes..
Thanks!
Awesome photo of you from the Mildura Supercross!
BenG
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12/20/2017
Location
Denton, TX US
3/30/2018 2:57am
Bike looks sweet already.
Ove
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137
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3/30/2018 3:25am
BenG wrote:
Bike looks sweet already.
Thanks!
propp2531
Posts
10
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12/16/2014
Location
Deptford, NJ US
3/30/2018 6:05pm
Nice. I got one just over a year ago. Was sitting in someones garage with very little done to bring it back to nearly new. I havent had the nerve to take it in the dirt yet.





nicko-31
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NY US
3/30/2018 6:29pm
Getting the gas tank white is a big delema I've been trying to resolve. How did you get yours so white Ove ?
Ove
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3/30/2018 10:08pm
nicko-31 wrote:
Getting the gas tank white is a big delema I've been trying to resolve. How did you get yours so white Ove ?
I cleaned it several times, but could not get the yellowing out.
I ended up buying a white perforated tank decal from Evo-mx.
Ove
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3/30/2018 10:12pm
propp2531 wrote:
Nice. I got one just over a year ago. Was sitting in someones garage with very little done to bring it back to nearly new. I...
Nice. I got one just over a year ago. Was sitting in someones garage with very little done to bring it back to nearly new. I havent had the nerve to take it in the dirt yet.





Nice one!
I can understand the hesitation to bring it out into the dirt, have the same dilemma with my build...:-)
nicko-31
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NY US
3/31/2018 5:14am
great . I did the same thing. There's a chemical process that can be used ,it's on a few Internet forum's.

1
Ove
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4/15/2018 4:09am
Billet Alu water pump impeller. A good upgrade from the stock plastic one.



Got the bottom finished, now waiting for the cylinder to get back from the machine shop. (Boring out to .50 oversize)



1
Ove
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NO
7/4/2018 6:31am
Out in the sun for the first time since last summer.
Some finishing touches and she is ready.
Have to weld up a new exhaust , install radiator hoses and some other stuff, but she is getting there









4
Ove
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7/13/2018 1:06am
chuckie108 wrote:
Awesome bike!!!
Thanks!
nicko-31
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NY US
7/17/2018 9:01am
Over, have you been able to race or ride the bike yet ?
Ove
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137
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7/17/2018 1:27pm
nicko-31 wrote:
Over, have you been able to race or ride the bike yet ?
No, still not finished with the exhaust. I will post a ride report when I have .
Ove
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137
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9/12/2018 11:28pm
And this is the bike completed.
Been a fun project
Hope you enjoy:












3
nicko-31
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411
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NY US
9/13/2018 8:54am
Bike looks great Ove. I had issues as well with my 33 year old carburetor and opted for a 38mm round slide Mikuni on my 1985 125-N. Worked well for me and it was only 100.00 In the US on ebay.
1
Ove
Posts
137
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NO
9/14/2018 1:59am
nicko-31 wrote:
Bike looks great Ove. I had issues as well with my 33 year old carburetor and opted for a 38mm round slide Mikuni on my 1985...
Bike looks great Ove. I had issues as well with my 33 year old carburetor and opted for a 38mm round slide Mikuni on my 1985 125-N. Worked well for me and it was only 100.00 In the US on ebay.
Thanks!
Yeah, I did do a cleaning and used the best parts i had from two carburetors, but look like I have to rebuild once more.
(Not sure what happened to my post where I wrote about the flooding of the carb..?)
Anyhow, the bike fired up and ran absolutely great, and had a strong midrange as I hoped it would have after the Eric Gorr mod I did to the cylinder, with the Boyesen Reeds.
Will install a complete FMF exhaust, and I think that will help as well.
Thanks for the tip on the carb, will look into something like that if I can't get the one I have to work.
propp2531
Posts
10
Joined
12/16/2014
Location
Deptford, NJ US
9/27/2018 11:41am
Ove wrote:
Got a basket case bike that I have as my winter project. Was one almost complete bike and a couple of engines and a frame when...
Got a basket case bike that I have as my winter project.
Was one almost complete bike and a couple of engines and a frame when I got it.
This is what I started with:







Tore it down and got the frame cleaned up, welded a few cracks and painted:



Rebuild began, all bearings etc replaced.
Öhlins shock rebuilt
Spokes etc replated
Wheels rebuilt
Some photos of the process:





















Engine getting new bearings, and overhaul of the crank.
Transmission was good
Doing some porting to the cylinder after reading Eric Gorr's book















The bike as it sits now.
It will be a Broc Glover "replica"
Since it's near impossible to get any parts, exhaust etc to do a proper replica, I will build it to look like Glover's 86 bike.





What pegs did you put on your bike? Mine still has the stock and I'm looking for bigger more modern pegs
Micahdogg
Posts
1267
Joined
1/3/2011
Location
US
9/27/2018 9:34pm
Great job on the resto! That is one of my favorite color combos!
1
wfoskir
Posts
181
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6/11/2017
Location
Half Moon Bay, CA US
9/30/2018 9:09pm
You did a great job. That bike looks awesome.
1
Ove
Posts
137
Joined
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NO
10/21/2018 9:14am Edited Date/Time 10/21/2018 9:16am
propp2531 wrote:
What pegs did you put on your bike? Mine still has the stock and I'm looking for bigger more modern pegs
Sorry for late answer Propp2531
I bought a set of Super Stock pegs from Parts Europe P/N 277311 (Parts Unlimited)
They are wider than stock, and looks almost stock.
Ove
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137
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10/21/2018 9:16am
Micahdogg wrote:
Great job on the resto! That is one of my favorite color combos!
Thanks!
My favourite color on Yamaha's too!
Ove
Posts
137
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NO
10/21/2018 9:17am
wfoskir wrote:
You did a great job. That bike looks awesome.
Thanks! Glad you like it.
Ove
Posts
137
Joined
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NO
10/21/2018 9:26am
I ended up with a complete FMF exhaust system on the bike.
Not too keen on the chrome looks of it, but it will have to do for now. Looking to get a "works" looking exhaust built for it.
Happy with the engine response. It has a really good bottom end with a serious mid range as well
Here is a short little video of the bike idling after the first start with the carb issues fixed.

1986 Yamaha YZ250S first start

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