Need Help! Questionable top end? Do I need to get this cylinder reconditioned?

[dk]

Need Help! Questionable top end? Do I need to get this cylinder reconditioned? ? 2005 yz 125

I bought a 2005 yz 125 last week and I am currently in the middle of doing the top end.  I noticed that the top of the cylinder is starting to break down!  Please review the pic and let me know if this is normal for a 125 or do I need to get this thing reconditioned?

Thanks in advance!

Dave

[TMKIWI]

Looks like it has had a sleeve put in and it has some electrolysis.
Not good.
Take it to an engine rebuilder and get some advice.

[dk]

I was told that they never touched the top end and it looks stock but I was afraid that i would have to take this in.  Man.  I guess you get what you pay for.  Thanks for the reply!

[ford832]

The plating down the side looks fine so there is nothing for the ring to snag-it would run that way no problem.You do run a high risk of having pieces flake off and gouging the piston/cyl or getting into the crank area.I'd fix it where you appear to have caught it before any more damage was done.Given that it's on the top edge,it just could be flaking due to age-or it could have been caused by a detonation issue.What does the head look like?

[cnrcpla]

I was told that they never touched the top end and it looks stock but I was afraid that i would have to take this in.

Maybe they weren't the first owners and they may not have touched it. But technically you can run the engine with that, but more than likely pieces will break off and go into your cylinder and scratch up the sides, and then you will be doing another top end job after the first few rides. It almost looks like someone tried to DIY a cylinder sleeve job by hitting that one with a chisel or something to get it out.  " title="Roll Eyes" class="smiley"> But engine specialist will more than likely re-sleeve it which is a bit more expensive than simply getting a top end done. The only thing is, those chips go even further than the sleeve, so I'm not sure what they would say about that.

[SachsGS]

You've got something funny going on there.Take the cylinder and head to a machinist and have him(her) measure for warpage, this YZ may have got hot at some point.

[Recovered]

looks like there has been some flakes right at the edge of the cylinder wall if it's flaked that much it's bound to flake more I know of a place that you might be able to send that cylinder to and exchange it for a replated one or a sleeved one they have both......Cylinder Exchange 1-760-815-0444 they have fast turn around

[dk]

Thanks for all the feedback.  I ended up picking up a new cylinder for $420!   
I am thinking this was pre-mature after reading further comments since this could be a bigger problem.  If the head is wrapped I am just on borrowed time.  Here are some pics of the head.  The bike was used in the desert and I am thinking with all the carbon buildup on the exahust side of the cylinder and gunked up power valve that she got hot.

[xandyx]

for me looks like only a casting flaw, nothing major.

aluminum doens't stick that well with sleeve metal, maybe it cracked those small bits.

doesn't seem to deteriorate and lead to a problem.

[cnrcpla]

Are those chips from the spark plug hole too? Or just oil? I can't tell.

[dk]

Are those chips from the spark plug hole too? Or just oil? I can't tell.

Just oil - I did a double take when posting the pics and looked at the head and it was just oil.

[dk]

I slapped her together last night and went to Pala this morning.  New piston and cylinder.  I did a 12 min warm up lap keeping it under half throttle.  Brought it back to the pits for a cool down.  Took her back out and didnt hold back.  Running very strong and super happy!

[cnrcpla]

That's good. Now I wish I had my cylinder back too