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YZ250 Identifying new to me yz250

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Alright so I picked up the yz250 from a guy that didn’t know a whole lot about what he had other than that he wrecked it and wanted to get it gone. After cleaning it up and getting it started I noticed it was a pain  to kick this thing over. I also noticed the head and cylinders are a different color than the case. Ran a compression test and I’m getting like 285 on a trusted gage. Then I noticed I have a metal head gasket. I think I have a big bore kit. Anyone else have any ideas? ThanksA7FC7F73-6EA5-47B4-8F8D-62458302C945.jpeg.13dd8a63017eec584185cfaf25a84900.jpeg

 

8FE566E8-9941-46EC-AFF2-D7250FC31705.jpeg

DCEF798A-5D5E-4D79-AF69-A066258B85A8.jpeg

Edited by jake644

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Man, I couldn't bring myself to ride it until I saw what was in that one. If that is really the compression and it doesn't have a chamber full of fluid I don't think it will like pump gas 😁

Edited by ossagp1

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^ Ya I tried running some local 91 non ethanol and I didn’t like the sounds it was making. I’m afraid I’m going to have to pull it apart and see what surprise is inside. 

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5 hours ago, jake644 said:

Alright so I picked up the yz250 from a guy that didn’t know a whole lot about what he had other than that he wrecked it and wanted to get it gone. After cleaning it up and getting it started I noticed it was a pain  to kick this thing over. I also noticed the head and cylinders are a different color than the case. Ran a compression test and I’m getting like 285 on a trusted gage. Then I noticed I have a metal head gasket. I think I have a big bore kit. Anyone else have any ideas? ThanksA7FC7F73-6EA5-47B4-8F8D-62458302C945.jpeg.13dd8a63017eec584185cfaf25a84900.jpeg

 

8FE566E8-9941-46EC-AFF2-D7250FC31705.jpeg

DCEF798A-5D5E-4D79-AF69-A066258B85A8.jpeg

What's this, tab for head gasket?

Id keep an eye on how it runs. Any fluctuating idle and I'd suspect crank seals are dry and cracked

Screenshot_20200522-050811~2.png

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Yes that is part of the metal gasket it looks very similar to the ones that come we it’s Eric gorr kit picture below is from his website I know it is a 4 stroke in the photo but gaskets are what I’m looking at. 

5A911E08-7D1D-4C50-BE7B-F4C9F7E3A33C.png

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5 minutes ago, jake644 said:

Yes that is part of the metal gasket it looks very similar to the ones that come we it’s Eric gorr kit picture below is from his website I know it is a 4 stroke in the photo but gaskets are what I’m looking at. 

5A911E08-7D1D-4C50-BE7B-F4C9F7E3A33C.png

Would be interesting to see the back side of that head, definitely had some cutting done to it to get 275.

Doesn't happen often that a kick start shaft breaks but if yours is remotely weak you'll find out soon kicking that mule

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Athena BB kits take O-rings like the OEM but bigger for the 72mm piston.

Didn’t Ohlins/Noleen make a BB kit (360) for the 250 at one time that took the regular head type gasket? But I didn’t think it was for the 99 up cases  

 

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It's definitely not an ohlins kit those where from the early 90's. That head gasket looks more like the one I've seen on the eric gorr yz295 big bore kits. 

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I had a Eric Gorr YZ295 kit and it had that same gasket. I also had high compression so your going to need more octane lest it detonate to death. Is that dirt around the spark plug coming from the plug treads? My compression was so high I had to really tighten the plug as it was coming loose. Be nice to see the condition of the top end prior to running it. With that level of compression I'd run straight VP110 or C12.

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1 hour ago, 2strokeYardSale said:

It looks like this Cometic gasket which is part of some BB kits. If you are really lucky you'll have a Wiseco piston with a part number on the top.

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That compression is insane. Stack another gasket? Recut the head?

You'll need to recut if your going to run 91-93 octane gas.

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18 hours ago, SmokinJoe said:

It's definitely not an ohlins kit those where from the early 90's. That head gasket looks more like the one I've seen on the eric gorr yz295 big bore kits. 

It wasn't on my EG295. It used o-rings. 

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Use an inspection camera to look down the spark plug hole to see the condition of your piston crown.Remove your pipe and shine a led light into the exhaust port and you can see the condition of your piston skirts and cylinder walls. When you start the bike, slowly push down on the Kickstarter until you get piston a little past top dead center, then bring Kickstarter back up and kick the bike over. ( this is the typically starting technique for a Cr or KX 500.)
 

https://www.homedepot.com/b/Tools-Power-Tools-Inspection-Cameras/N-5yc1vZc2gm

 

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4 hours ago, MX Tuner said:

It wasn't on my EG295. It used o-rings. 

That's interesting as it was on my EG295 which I bought from EG.

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Well it looks like I’m in trouble because I’m a newer rider and going from a kids drz125 and a fz07 streetbike im 25 and 205 LBs and I have not rode this thing yet but I’m afraid it’s too much bike for me what do you guys think? Thanks guys for all your replies. 

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Getting a yz250 is never a mistake. You can tame it down untill you get comfortable with it. The first thing to do on any used bike is take apart the top end to check condition. Once apart assuming it is an Eric Gorr 295, call him and tell him you would like to change it to pump gas. Some popular taming mods are lower compression, 250x power valve spring, flywheel weight, retarded timing, g2 throttle tamer.

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Maybe the PO got crazy and cut the head too much.

I'd take the head off and CC it.

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