Is this cylinder still ok to use for a little while longer on this yz 250

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10/15/2019 3:34 PM

Is this still ok to use ??? Cant feal the scratches at all










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10/15/2019 4:09 PM
Edited Date/Time: 10/15/2019 4:10 PM

No.... those scratches are too deep, and it looks like there’s some plating damage as well below the exhaust port...

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10/15/2019 6:44 PM

Paul_Pitzonka wrote:

No.... those scratches are too deep, and it looks like there’s some plating damage as well below the exhaust port...

My finger nail dont catch its smooth. But I mean it is used.

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10/15/2019 6:45 PM

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10/15/2019 7:00 PM
Edited Date/Time: 10/15/2019 7:04 PM

Im still going to say no, but you can De-glaze it see how it looks... this is more of an issue than the scratches...

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10/15/2019 10:32 PM
Edited Date/Time: 10/16/2019 5:47 PM

Who dose replating for cheep but is reliable.. I only ran 2 pistons through this head..my ktm was did by Millennium Tech and I've ran quite a few through it I'm not sure but I haven't changed it in like 4 years and it still looks better than this one.. but Millennium Tech is way too expensive

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10/16/2019 3:51 AM

Millennium tech and powerseal USA. Millennium charges $300 and powerseal charges $200. Both equal quality.

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10/16/2019 3:55 PM
Edited Date/Time: 10/16/2019 3:56 PM

kb228 wrote:

Millennium tech and powerseal USA. Millennium charges $300 and powerseal charges $200. Both equal quality.

Hell I took it to my local shop that works on bikes they said I can get a nother 40 or 50 hrs out of it before I need to send it off if not longer..

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10/16/2019 5:34 PM

kb228 wrote:

Millennium tech and powerseal USA. Millennium charges $300 and powerseal charges $200. Both equal quality.

Toby_Blevins wrote:

Hell I took it to my local shop that works on bikes they said I can get a nother 40 or 50 hrs out of it before I need to send it off if not longer..

Id find another shop because theyre wrong. I dont think anyone is going to say run it with that gouge paul highlighted. I certainly wouldnt be running it. Did you even measure the bore to check if its in spec? If not youll get piston slap and blow it up.

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10/16/2019 5:46 PM

kb228 wrote:

Millennium tech and powerseal USA. Millennium charges $300 and powerseal charges $200. Both equal quality.

Toby_Blevins wrote:

Hell I took it to my local shop that works on bikes they said I can get a nother 40 or 50 hrs out of it before I need to send it off if not longer..

kb228 wrote:

Id find another shop because theyre wrong. I dont think anyone is going to say run it with that gouge paul highlighted. I certainly wouldnt be running it. Did you even measure the bore to check if its in spec? If not youll get piston slap and blow it up.

A gouge is a little bit of an exaggeration it's pretty smooth to be honest but ima probably send it off with my other cylinder so I won't need to worry about it for a long long time

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10/16/2019 6:01 PM

kb228 wrote:

Millennium tech and powerseal USA. Millennium charges $300 and powerseal charges $200. Both equal quality.

Toby_Blevins wrote:

Hell I took it to my local shop that works on bikes they said I can get a nother 40 or 50 hrs out of it before I need to send it off if not longer..

kb228 wrote:

Id find another shop because theyre wrong. I dont think anyone is going to say run it with that gouge paul highlighted. I certainly wouldnt be running it. Did you even measure the bore to check if its in spec? If not youll get piston slap and blow it up.

I agree... Find a different shop. Plain and simple that cylinder is hurt... my highlighted area may also be melted piston (Although I doubt it)... If it is it can be removed with some muriatic acid... If the shop didn’t even bother to run a hone through it to deglaze it, and take a measurement with either a bore gauge, or a snap gauge and outside mic then their opinion doesn’t hold much weight... There’s a difference between running and running correctly... The whole 40-50hr thing is nonsense you can’t measure a bore in hrs... it’s fairly black and white... either the bore is within service limit, or it’s not...

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10/17/2019 6:09 AM

Another option is to replace the cylinder. You don't mention the model year, but is this the same cylinder that is used on about a dozen model year YZ250s? If so, a good used cylinder may not be too hard to find and you may spend less than having current cylinder reworked. Not to mention, if you have a way to sell current cylinder, you might be surprised how little you spend going this route.

Yes, if you are looking to put this engine back together, race at the highest level and have it last as long as possible, then sure, you need to start with as 'new' as possible.

But, if you are not wringing that YZ out and riding a lot, the used cylinder route may be a good bet.

I've have gone the used cylinder route a few times, with no regrets - but again neither my skill level nor riding frequency would fall into the 'high' category.

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10/17/2019 8:08 AM

KX500 wrote:

Another option is to replace the cylinder. You don't mention the model year, but is this the same cylinder that is used on about a dozen model year YZ250s? If so, a good used cylinder may not be too hard to find and you may spend less than having current cylinder reworked. Not to mention, if you have a way to sell current cylinder, you might be surprised how little you spend going this route.

Yes, if you are looking to put this engine back together, race at the highest level and have it last as long as possible, then sure, you need to start with as 'new' as possible.

But, if you are not wringing that YZ out and riding a lot, the used cylinder route may be a good bet.

I've have gone the used cylinder route a few times, with no regrets - but again neither my skill level nor riding frequency would fall into the 'high' category.

I dont race.. it's a 2001 very hard to find parts.. I just picked this up for 400 .. I'm still debating on taking it apart and sending crank off to be balanced or just using it for a while


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10/17/2019 9:09 AM

How sure are you that the later MY cylinders don't work on an '01? The reason I ask is that some sources I've seen say that '02 to current cylinders work for '99-'01 as well, in spite of part number changes. I have no doubt the P/N changed for the newer cylinders, but was the change significant enough that a newer cylinder can't be used?

When you look at YZ250 pistons for example, it says '99 to current'.

I'm just asking - I don't know. And if you have researched this thoroughly, please disregard.

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10/17/2019 9:35 AM

KX500 wrote:

How sure are you that the later MY cylinders don't work on an '01? The reason I ask is that some sources I've seen say that '02 to current cylinders work for '99-'01 as well, in spite of part number changes. I have no doubt the P/N changed for the newer cylinders, but was the change significant enough that a newer cylinder can't be used?

When you look at YZ250 pistons for example, it says '99 to current'.

I'm just asking - I don't know. And if you have researched this thoroughly, please disregard.

If I remember correctly the newer cylinders and heads will swap over... they made changes in both port timing, and compression ratio... the cases and crank do not they use a different crank half and main bearing... OP if you’re not a pro who’s wfo all the time don’t worry about balancing a 2 stroke crank I would just have it rebuilt and trued...

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10/17/2019 9:44 AM

Also engine parts from the 2001 are still easy to find. I believe the stuff thats different is in the bottom end.

Getting a crank rebuilt is $190 from ken oconnor. Dunno why you wouldnt do that.

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10/17/2019 2:14 PM

KX500 wrote:

How sure are you that the later MY cylinders don't work on an '01? The reason I ask is that some sources I've seen say that '02 to current cylinders work for '99-'01 as well, in spite of part number changes. I have no doubt the P/N changed for the newer cylinders, but was the change significant enough that a newer cylinder can't be used?

When you look at YZ250 pistons for example, it says '99 to current'.

I'm just asking - I don't know. And if you have researched this thoroughly, please disregard.

I'm not sure tbh..

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10/17/2019 2:18 PM

kb228 wrote:

Also engine parts from the 2001 are still easy to find. I believe the stuff thats different is in the bottom end.

Getting a crank rebuilt is $190 from ken oconnor. Dunno why you wouldnt do that.

Now that is not true..took forever to find a case one company had 1 new and was 1000 I'm good on that.. somethings are easy to find yes... but other things not so much and parts are 3 times more $$$ then other bikes. New parts are almost impossible to find.. I was only able to find a high gear ratio for my transmission but they did have single gears

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10/17/2019 2:19 PM

kb228 wrote:

Also engine parts from the 2001 are still easy to find. I believe the stuff thats different is in the bottom end.

Getting a crank rebuilt is $190 from ken oconnor. Dunno why you wouldnt do that.

And I'm going to get my crank in my old case rebuild this winter and put it in next time my put a piston in but this case hase a good crank so I'm leaving it alone for now

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10/17/2019 3:38 PM

Riding on a used crank Off of eBay That you have no way of knowing the true history of would scare the hell out of me...

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10/17/2019 3:59 PM

Paul_Pitzonka wrote:

Riding on a used crank Off of eBay That you have no way of knowing the true history of would scare the hell out of me...

It has no play in it at all.. I'm sure it will be ok till I rebuild top end in April

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10/18/2019 5:40 AM

Why are you buying an entire bottom end?

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10/18/2019 11:26 AM
Edited Date/Time: 10/18/2019 11:57 AM

kb228 wrote:

Why are you buying an entire bottom end?

Because left side case is busted behind stator where bearings seat.. and it's not a good ideal to just buy the left side case and not the right they are all a little different it can cause problems.its always best to buy both sides..

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10/19/2019 8:14 PM

This is the new case.. I'm sending crank off in 5 or 6 weeks has a pro series crank in it never hurd of that. Sending cylinder off with piston when I receive it. Had some Mark's that looked like cracks but they sanded away

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10/19/2019 10:37 PM

Why sand it if your sending it out? Actually, why would it be ok to sand it?

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10/19/2019 11:08 PM

Chance1216 wrote:

Why sand it if your sending it out? Actually, why would it be ok to sand it?

I'm not talkin about sanding the cylinder the new case had a couple of Mark's that look like cracks so I sanded those down to make sure they were not cracks not the cylinder

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10/22/2019 11:30 AM

Everybody says send it off, which is what I would do if I was racing it. It just depends on what you are doing. If you are trail riding and goofing off, then run it. The bike will run with that cylinder. If you are racing it then no I wouldn’t because it could be dangerous. You don’t wanna be going off the face of a jump and the motor bog down and lock up. If you decide to use the cylinder just know you are taking a chance of causing more issues. There’s gonna be a lot of play in that piston to cylinder clearance. When it blows up it’s gonna more then likely mess the cylinder up more, trash the crank, and you will probably have to have your head resurfaced. Can you run that cylinder for a few more hours? Yes. Would I do it? No. And actually my friend had a cylinder shipped to millennium and they couldn’t fix it. he had to pay shipping there and he had to pay shipping back after they said there shop couldn’t fix it. Then he had to buy a new cylinder. So, you are taking a huge financial and physical risk, depending on your intentions for the bike, when you run that cylinder.

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