1995 Yamaha yz250 resto (Attention Engine Gurus!)

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1/15/2018 3:44 PM
Edited Date/Time: 1/23/2018 5:15 PM

Picked up this beaut today. It was sitting in a garage with a layer of dust, wasp mud huts and other junk on it.
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About 30 mins after I got it home...

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The low down:
The engine is locked up, needs a subframe, plastics are garbage, needs at least a front tire, chain, sprockets, suspension needs rebuilt.

The plan:
It will be a winter/spring project and on going after that. My goal right now is to get it running good then do cosmetics. It did com with some nice parts: Boyesen rad valve, billet big bar clamp, clarke tank, Pro Circuit full exhaust and the frame is in very good condition. But I’m undecided if I want to keep the 95 look or update the subframe and plastics? Still not sure if it can be done.

If anybody has parts laying around please let me know!

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1/15/2018 4:58 PM

Sweet, man! I'm doing a '95 myself! (you got a better deal than me!!)

On the subbies- you can pick them up all day on eBay for about $75-$100 but they are all going to have some
bends, tweaks, etc. 125 will fit as well; it will just have an additional silencer bracket on the lower right tube.
AC Racing makes them for about $275.00 http://www.acracing.com/category-s/145.htm

This guy is selling a titanium one for $250.00 https://nh.craigslist.org/mpo/6436763668.html

From what I've read, you can update plastics but yes, you will have to update subby and seat. There's a couple threads floating around on other forums of guys that have done it.

Later model suspension bolts right on. Seat bases are REALLY hard to come by so hang on to yours!

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1/15/2018 7:48 PM

FWYT wrote:

Sweet, man! I'm doing a '95 myself! (you got a better deal than me!!)

On the subbies- you can pick them up all day on eBay for about $75-$100 but they are all going to have some
bends, tweaks, etc. 125 will fit as well; it will just have an additional silencer bracket on the lower right tube.
AC Racing makes them for about $275.00 http://www.acracing.com/category-s/145.htm

This guy is selling a titanium one for $250.00 https://nh.craigslist.org/mpo/6436763668.html

From what I've read, you can update plastics but yes, you will have to update subby and seat. There's a couple threads floating around on other forums of guys that have done it.

Later model suspension bolts right on. Seat bases are REALLY hard to come by so hang on to yours!

Thanks man! I saw your build prior to buying it. Will you be sticking with stock plastics?

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1/15/2018 7:56 PM

I can get you dealer pricing on rockymountain text me for prices 570-606-7687

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1/15/2018 8:24 PM

I'm pretty stoked on what I presume to be the stand. Good luck on the build!

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1/15/2018 8:52 PM

Zach_K wrote:

Thanks man! I saw your build prior to buying it. Will you be sticking with stock plastics?

Yes, definitely. That's why I went with this era; I love the styling of this bike.
Though I'm struggling between going with the purple frame and the matching graphics
or the blue frame with the blue "works" graphics. I'll probably go purple as that
was my original plan.

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1/16/2018 6:34 AM

DTR830 wrote:

I can get you dealer pricing on rockymountain text me for prices 570-606-7687

Thanks!

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1/16/2018 6:38 AM

SLOWTIME wrote:

I'm pretty stoked on what I presume to be the stand. Good luck on the build!

That’s actually my home built stand. A while back I had wr250r and a Clapped our Ktm 65. I built that stand for he purpose of holding that bike for a resto and I just stuck with it. It’s a perfect step for loading a bike into my 2500 and I get coments on it all the time with 16 Ktm 250 fe sitting in it

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1/16/2018 7:03 AM
Edited Date/Time: 1/16/2018 7:49 AM

I’ll be posting photos on my phone then updating later on..

Breaking it down: luckily no seized bolts so far. Lots of PB blaster and wb.
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Next is to work on the rear end
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Popped open the engine to get a look at what I could be dealing with. From the cylinder you can see some type of fluid; I'm guessing coolant? What you guys thinks? Hows she look?
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Working on the rear end...The brake fluid is (well what is left) is a black sludge
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SO I'm stuck. Last night I loaded the front swing arm bolt with lots and lots of lube as I couldn't get the bitch to budge. Every "big bolt" on the bike two sides to work with except this bolt. Any tips on getting it? Hopefully all the lube penetrates it and its easier the next time I work on the bike.

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1/16/2018 8:46 PM
Edited Date/Time: 1/16/2018 9:03 PM

Sitting overnight and few good wacks she came loose
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Yum...all from the oil drain plug
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THIS is when I could use some engine gurus help. Before I completely dissasemble the engine completely, what do you believe happened here...My thought is blown crank bearings due to the flywheel positioning
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finally out!
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Clutch is in pretty damn good shape. No notches in the basket
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more yum
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no scores or notches
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The last engine (ktm 65) did not have this. What is it?
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Cylinder looks pretty good
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no major damage to the piston
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notches in the con rod
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1/17/2018 1:58 AM

Cant wait to see the progress. I love mid 90s YZ250s I’m currently building a 98.

It’s the powervalve linkage.

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1/17/2018 3:38 AM

Looks like it blew the head gasket and washed out the crank bearings, also, it may have hydraulically seized when the cylinder filled with coolant and took out the crank bearings. The top end looks surprisingly good minus the power valve.

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1/17/2018 7:31 AM

Correct me if im wrong but in one of your pics of the cylinder (while still mounted to the cases has a +/-5mm aliminum spacer under it correct?

That means youve got one of the YZ250’s that someone put the Yamaha “Long Rod Kit” in it!!! Made all those Yz250’s from that era absolute rockets!! It was a really popular mod that you could get directly through Yamaha after getting one of their “Wrench Reports” (pre GYTR I believe) and that rod was actually out of an 88 YZ250 as part of the kit.... make sure to try and reinstalling those seemingly insignificant parts as part of your restoration .... youll have dam bear a full blown factory engine with that mod and a little porting. The LR kit didnt alter displacement surprisingly and im not sure exactly how common they were back in the day bec this was just a tad bit shy and still in the ‘dark ages’ as before there was internet and this setup was the main reason any racer in the SX series would always nad a holeshot or a dam good start.... just ask Jeff Emig and Chicken, they both lamented on about how fast their 94 bike was.

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1/17/2018 7:47 AM

Lightning78 wrote:

Correct me if im wrong but in one of your pics of the cylinder (while still mounted to the cases has a +/-5mm aliminum spacer under it correct?

That means youve got one of the YZ250’s that someone put the Yamaha “Long Rod Kit” in it!!! Made all those Yz250’s from that era absolute rockets!! It was a really popular mod that you could get directly through Yamaha after getting one of their “Wrench Reports” (pre GYTR I believe) and that rod was actually out of an 88 YZ250 as part of the kit.... make sure to try and reinstalling those seemingly insignificant parts as part of your restoration .... youll have dam bear a full blown factory engine with that mod and a little porting. The LR kit didnt alter displacement surprisingly and im not sure exactly how common they were back in the day bec this was just a tad bit shy and still in the ‘dark ages’ as before there was internet and this setup was the main reason any racer in the SX series would always nad a holeshot or a dam good start.... just ask Jeff Emig and Chicken, they both lamented on about how fast their 94 bike was.

You are correct! I noticed that last night. I’m pretty sure this was originally owned by a racer at some point. I keep finding little surprises in this bike

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1/17/2018 8:23 AM

That picture is the power valve. Really clean that up if you can and make sure it opens fully and also returns smoothly. If it doesn’t work properly, the bike will not run right.

Tomm55x is spot on with the hypothesis. Everything looks in really good shape minus corrosion. My guess is they put the LR kit in improperly and blew the head gasket and locked it up within a few hours. Everything else looks pretty good. Can’t really see the cylinder, but judging from the gaskets, there isn’t a whole lot of wear.

One thing to watch out for is the nikasil plating looking deformed or cracking from hydroshock. If the coolant rapidly cooled the walls while under high load, it could affect the plating and deteriorate it.

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If you're not mixing gas, you're not haulin ass.

1/17/2018 11:11 AM

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1/17/2018 3:42 PM
Edited Date/Time: 1/17/2018 3:45 PM

Man Ive never seen a rod bend like that on a two stroke. Looks like it hydro locked at some point from blown head gasket. Make sure you surface that head/check for warpage

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1/21/2018 4:30 PM

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1/22/2018 6:24 AM

That’s one hell of a seizure! I think it’s due for a full rebuild sick

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If you're not mixing gas, you're not haulin ass.

1/22/2018 6:42 AM

Also this was fun...over torqued bolt
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1/22/2018 8:17 AM

blink MC mechanic for 30+ years and NEVER seen a rod like that
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1/22/2018 8:44 AM

lumpy790 wrote: blink MC mechanic for 30+ years and NEVER seen a rod like that

It’s pretty f’ed up. I’ll have to see if the part number matches up with the long rod kit. Maybe prior owner had the wrong rod?

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1/22/2018 8:53 AM
Edited Date/Time: 1/22/2018 10:14 AM

Nice Pics, man!

You got your work cut out for ya! I'll certainly follow you progress. I'd replace every bearing since you have it split and give the tranny and water pump a good going over as well. Any internal shaft type mechanism should be properly evaluated for trueness. Seizures can pass mucho damage onto other components. Keep up the work and good luck.



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1/23/2018 6:28 PM
Edited Date/Time: 1/23/2018 8:57 PM

Plans may change and may end up parting it out. Cost is a little much to justify because of it needing work on both top and bottom end... ?

Nevermind
Stopping with the logical nonsense this bike is to much fun

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1/23/2018 7:34 PM

Zach_K wrote:

Plans may change and may end up parting it out. Cost is a little much to justify because of it needing work on both top and bottom end... ?

Nevermind
Stopping with the logical nonsense this bike is to much fun

WAT? Naw, man! Don't say that!

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1/23/2018 7:56 PM

FWYT wrote:

WAT? Naw, man! Don't say that!

I’m still debating but I did a spreadsheet and I probably should not have...

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1/23/2018 9:00 PM

She’s in to good of shape.. this has to be powdered
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New toy brings me happiness...just the brass brush
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1/23/2018 9:44 PM

Zach_K wrote:

Plans may change and may end up parting it out. Cost is a little much to justify because of it needing work on both top and bottom end... ?

Nevermind
Stopping with the logical nonsense this bike is to much fun

FWYT wrote:

WAT? Naw, man! Don't say that!

Zach_K wrote:

I’m still debating but I did a spreadsheet and I probably should not have...

Yeah, that's precisely why I do NOT keep track!! laughing laughing laughing laughing

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1/24/2018 2:42 PM

Dude you HAVE TO finish the rebuild of this bike just for the special long rod kit alone! Thats a special mod and if youre gonna be replacing that rod make sure you get the rod from a 1988 YZ250 thats the rod that was used for this special kit and like i mentioned above. This engine if you fix it up properly will be an absolute MONSTER but overall very rideable. That was a huge power gain mod and was the reason there were so many Yamaha holeshots for the 1994-1995 season and even Emig recently posted his 94 YZ250 was one of the fastest bikes he ever raced.

Also i agree this bike might be a racer owned bike and possibly a little bit of a special bike, although i could be wrong but the frame appears to have some gussets welded onto it as well....might want to check into that and if you can run the vin you could possibly find the bike owner history and may discover you found a diamond in the rough.

Im dying to build an Emig replica 1994 bike with the long rod kit it would be so cool!!

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1/24/2018 4:23 PM

That is a nice find, and you should proceed with it. Cheaper than buying a new bike, is in great shape, and has the cool factor. People stare at my 96 CR250 all the time, and I’m pretty sure it’s not because of the guy riding it. (Okay, maybe)
Owned a 94, with the kit, and yes, it was a rocket. From what I recall, the 95 was a mid-range only motor, and I’m not sure porting will change that. If you are after an electric motor, the 94 cylinder might be the way to go, and it was better than my 93. No hit, just linear power, and string. If a punchy mid-range motor is what you want, proceed.

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