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295 Cylinder Plating Crack

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Hey guys I have a 2005 yz295 that has 20 hours. It is set up for the wider powerband porting and race gas head. The bike has been very hard to start recently so I decided to change the piston even though it has 220 psi of compression.

Upon taking the cylinder off I found a 10 thou-.0010 groove worn into the piston on the exhaust- clutch side of the bike. The groove goes the whole way through both ring grooves down to the skirt.

When looking at the cylinder there is a piece of plating that is cracked between the exhaust port and the boost port. All of the other ports plating is polished and the plating is flush with the port except this one. It looks like this piece of plating was never polished and is hanging past the edge of the port. It really looks like it was never dealt with when it was plated, what do you guys think?

I don't have a problem paying to get it replated and i have a new piston, but it looks like it might be there fault. I will give them a call Tuesday when there open to see what they say. Although my 1 year plating adhesion warranty expired 8 months ago. Have you guys ever seen this? Do you think it's there fault? I'm sure with the volume they do some mistake is bound to happen. Just wanted to get your guy's opinions.

Here's some pics

ImageUploadedByThumper Talk1378140184.007016.jpgImageUploadedByThumper Talk1378140220.627396.jpgImageUploadedByThumper Talk1378140277.121175.jpgImageUploadedByThumper Talk1378140304.588118.jpgImageUploadedByThumper Talk1378140341.209034.jpgImageUploadedByThumper Talk1378140396.076048.jpg

Thanks

Ryan

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I think that the cylinder may have cracked there it looks like in the pics material is pushing outward it's common for this port to wanna crack stock and with it being a 295. I am thinking it is an over bore of the stock jug right? and there is less material there and it fatigued and cracked snagging the piston which is probably holding it in place from dropping into the cylinder.

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My cylinder cracked there as well. Millennium welded it up, said it was ubber common on Yz250's, and said they can't warranty their plating in that are as it was that common. Dunno, thats what I was told over the phone ~4 years ago.

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I have seen this happen many times on Pro stock Drag snowmobile engines. That is a hot spot with the triple port. A lot of guys will grind the plating there to see if it is cracked or not. If it is not cracked a lot of guys run it with the plating missing in that area. I know it sound like a very bad idea but a friend of mine did that for two years before replating and it did not hurt the cylinder. I would have thought it would gouge the aluminum away but it did not. As for Plating I prefer US chrome as I have had to many problems with Millennium. US chromes plating is harder and last longer. You can also plate up to .020 per side with there plating which resist flaking. You would have to bore it over size .010 for that much plating but it works.

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Yes the 295 takes the stock 66.4mm bore to 72mm. I was surprised this happened so soon with only 20.4 hours on it. I will call him tomorrow when there open and send it in for plating. I'd only send it to him just because he knows the kit best and invented it.

Adam how many hours did your cylinder have on it when it cracked?

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That does not look like one of EG's pistons unless it was an earlier version as the new ones have oil holes in that spot to help stop this type of issue.

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The cracking is fairly common especially on a big bore.

In this case hard to say if cylinder cracked our not but it certainly looks so.

 

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NitrousR1, I'm with harrperf. I'm not certain, but doubt it's a case of plating coming away.  That separated bit looks like it's been pushed away rather than flaked off.  I'm wondering if some valve vibration caused or contributed to the cracking.  Does there seem to be any abnormally large amount of play in that valve right behind the chunk?

 

If it is not cracked a lot of guys run it with the plating missing in that area. I know it sound like a very bad idea but a friend of mine did that for two years before replating and it did not hurt the cylinder. I would have thought it would gouge the aluminum away but it did not.

Very interesting he could run it like that for so long.  I would have guessed that little bridge does a lot to stop the ring bulging at that position. So with no plating there I'd guess the ring would get seriously worn and/or chip away the plating just above and below the bridge.

 

 

That does not look like one of EG's pistons unless it was an earlier version as the new ones have oil holes in that spot to help stop this type of issue.

Good to learn that.  I can understand the extra oil slowing down the wear of the ring at that position, but this chunk looks like there's more going on.

Edited by numroe

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NitrousR1, I'm with harrperf. I'm not certain, but doubt it's a case of plating coming away.  That separated bit looks like it's been pushed away rather than flaked off.  I'm wondering if some valve vibration caused or contributed to the cracking.  Does there seem to be any abnormally large amount of play in that valve right behind the chunk?

 

Very interesting he could run it like that for so long.  I would have guessed that little bridge does a lot to stop the ring bulging at that position. So with no plating there I'd guess the ring would get seriously worn and/or chip away the plating just above and below the bridge.

 

 

Good to learn that.  I can understand the extra oil slowing down the wear of the ring at that position, but this chunk looks like there's more going on.

 

My buddy took a die grinder and just smoothed out where the plating was flaked off. Ya I was total surprised he did not need a new cylinder. The same guy once had about a 1/2" of plating missing above the exhaust port and rode in on his trail snowmobile like that for approx 1500 miles. The only reason I know this is I sold him that cylinder cheap and he rides with our group. He is a tight wad and would rather cobble stuff than fix it right.

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That was one of his earlier pistons, the work was done november 2011. The new piston I got is the current type with oiling holes and coated skirts. The bike also had the older single layer head gasket. I have Mainly been riding a yz450 and a yz85-105 supermini since this bike has been hard to start recently probably due to this crack and the race gas head.

The powervalve is tight as I wondered if it was loose and caused this crack. It also moves freely and was pretty clean. Eric had me send back the cylinder with the powervalve installed as well as the old and new piston. He also wanted to look at it before he charged me, although I'm fine with paying for it. I was mainly just surprised this happened with only 20.4 hours. How long do your guys 295 cylinders last?

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That was one of his earlier pistons, the work was done november 2011. The new piston I got is the current type with oiling holes and coated skirts. The bike also had the older single layer head gasket. I have Mainly been riding a yz450 and a yz85-105 supermini since this bike has been hard to start recently probably due to this crack and the race gas head.

The powervalve is tight as I wondered if it was loose and caused this crack. It also moves freely and was pretty clean. Eric had me send back the cylinder with the powervalve installed as well as the old and new piston. He also wanted to look at it before he charged me, although I'm fine with paying for it. I was mainly just surprised this happened with only 20.4 hours. How long do your guys 295 cylinders last?

I have 170 hours on mine at the moment

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Ryan, did you have Eric 295 your personal cylinder or did you do a cylinder exchange?  Just curious what the condition of the cylinder was before it was bored......was it high hours or maybe the cylinder was seized hard and that area was compromised?

 

 

Sent you a PM on the exhaust if you're still interested.

Edited by moto2000

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Did you have Eric 295 your personal cylinder or did you do a cylinder exchange?  Just curious what the condition of the cylinder was before it was bored......was it high hours or maybe the cylinder was seized hard and that area was compromised?

 

 

Sent you a PM on the exhaust if you're still interested.

I bought a full kit off EG. everything looked fairly new. I couldn't tell if it was brand new or not.

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I didn't want the cyl exchange just in case the cyl was thrashed, so I had him use my cylinder. It was a good shape 265 cylinder with no cracks or plating rubbed off.

The cylinder is still in the mail as of today. I heard of others cylinders lasting hundreds of hours as stated above. We will see what happens. I appreciate the offer on the exhaust, I am going to hold off until I know how much this is going to cost me, thanks though

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Had this exact same thing happen to me....TWICE!!  Had a 295 done 3 years ago put 20-25 hours max on it and blew during the middle of a hare scramble.  The power valve bolts came undone so I blamed it all on the power valves coming undone and somehow that cause it to crack.  Bought another 295 kit and bam same about of time, same thing happened, on both sides of the cylinder.  At this point I had enough, bought a brand new stock cylinder and put over 80 hours on it without a problem, before I sold the bike this past July.

 

DestoyedPiston.jpg

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2sd, the second time it happened, what did you conclude was the cause? What did EG say about it?

PV related again? If yes, were your PV parts covered in carbon or lubed and smooth?

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2sd, the second time it happened, what did you conclude was the cause? What did EG say about it?

PV related again? If yes, were your PV parts covered in carbon or lubed and smooth?

Same exact thing happened. Bike was jetted perfect, was running 100 octane unleaded to avoid detonation. The second cylinder I checked the power valves frequently after the screws came out on the first one and every time I checked them they were perfectly lubed with no wear or carbon. I just assumed after the second one went that I was really unlucky, still don't have hard feelings for Gorr just can't deal with having a big bore like that. I ride a lot and I need parts available on a dime and a engine that will put up with my abuse.
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To keep everyone updated, I spoke to eric on the phone today and they are covering the plating under warranty. Normally the plating adhesion warranty is 1 year but he is going to cover this just because of the low hours. I was glad to hear this to say the least, it should be shipped by the end of next week.

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Good stuff.  Was it simply a plating break-away, or was the metal underneath deformed at all?

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He did not say but I will ask him when I call next week. I imagine that piece of plating cutting into the piston was the reason the bike was so hard to start.

I also want to ask if they will pay for the piston since the plating destroyed it, but I'm fine if they don't pay for that as I have a new one here allready. I figure its worth a shot as people do that to us all day everyday

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