Noticed a flat spot when honing cylinder

[moose_338]

56 minutes ago, 298 said:

"So please don't go telling people it's fine to do because you do it or you know some "factory mechanics" that do."

On the other end, don't say you can't or shouldn't since you prefer not using one. Or because you don't know how to use one.

Nobody is saying to use one. I'm just saying using one isn't the death for all plated cylinders, like some are recommending here. There is a proper way to use one. If you can't use one without destroying the plating on your cylinder, then maybe you shouldn't be giving advice on them.

There is no proper way to use a hone for a plated two stroke cylinder though, that's what I just explained. It has a very high chance of chipping off the plating by the edges of the ports. And on the off chance it manages to remove said plating you only have microns of material to play with. It can and will be the death of a cylinder.

 

This is no reason to use a hone when scotchbrite does the same thing with no risk. I don't know what so hard to understand about that.  You also have to remember your on here writing advice that people that may not be the most knowledgeable and skilled in this then some and you run the risk of them ruining an engine on your misguided advice...

[Nevada Al]

Prime example I point to the OP and his “honed cylinder “. Jury verdict please

[markmc2]

put an hours meter on it, run it, let us know results. inquiring minds want to know.

[YZDOC]

?

Copy that! 

 

 

[Motox367]

5 minutes ago, 2 STOKE YZ DOC said:

?

Copy that! 

 

 

Roger ???

[SmokinJoe90]

The only time I had a cylinder honed was after like 6 years of owning my 06 yz 144 Gorr did. I sent it back to him to have it diamond honed which has been great but this year it finally gets a replate. Just to be clear I had the bike 144'd in Jan 06 so that's 10 years on that plating. 

But I only use a scotch brite pad on it to clean it up at a 45 degree angle. I only sent the 144 jug to be honed by Gorr at the time cause of some piston material build up I was getting on the bottom below the exhaust bridge I couldn't remove fully by using the scotch brite pad on it.

[YZDOC]

Whenever someone comes on here and contradicts their own posts/statements in the same thread, it’s almost like I walked over a trolls bridge and hearing, “who’s that trip trapping across my bridge”... 

If you are not a certified mechanic and/or a machinist, and/or don’t know what the hell you are doing, STAY THE HELL AWAY FROM THESE TYPE TOOLS, or you will destroy whatever it is you are dicking with...

Me, not certified, not a machinist, but I have built enough engines over my lifetime to know what’s right and wrong. I have been told I am certifiable by the little lady! 

? like a ?

[YZ144FirstTimer]

Is this correct?

"On 2 strokes, the crosshatch matters (obviously), just a whole lot less. We don't have oil rings (breaking news). On a 4 stroke, it's obviously much more important."

I always thought because we dont have oli rings to keep the walls lubed that we needed the cross hatching more so to hold it there for the ring (and piston) to glide over.

[YZDOC]

Oil rings prevent engine oil from entering the combustion chamber. 

Just like valve seals. 

[jimspac]

That is the real problem. Never use a ball hone within a 2 stroke cylinder regardless of plating or not. Ball hones are for 4 stroke cylinder with no intersecting ports. The hones with 3 or more long stones are best on 2 cycles with larger ports to bridge. I am a certified machinist and engineer. With the correct media you can clean a nikisil bore but must take care to not increase the bore size. That takes feel that few non professionals have.

[jeffoff]

Worked with top mechanics in the f1h2o circuit, rebuild dozens of those mercury v6 2stroke race engines. I was teached to hone the plated cilinders with every rebuild... more of deglaze and put back crosshatch, we did this with a diamond hone. For replating we send the blocks to us chrome, best results for us...

When i went to a known ktm mechanic for a new piston, i asked him to give it a little hone because of marks i did not like. He refused...  

If i had the the correct tools i would do it with every rebuild of my bike... Maybe at the expense to replate quicker...

[298]

2 hours ago, YZ144FirstTimer said:

Is this correct?

"On 2 strokes, the crosshatch matters (obviously), just a whole lot less. We don't have oil rings (breaking news). On a 4 stroke, it's obviously much more important."

I always thought because we dont have oli rings to keep the walls lubed that we needed the cross hatching more so to hold it there for the ring (and piston) to glide over.

If a 4 strokes oil rings do not seat, you will burn oil. Depending on how often you change your oil, you could run it low much quicker than you think and potentially seize the motor (you'd have to really be ignoring some signs, like constant blue smoke).

On a 2 stroke, if rings don't seat you'll get blowby, and the cylinder walls will get glazed.

Edited February 7, 2018 by 298

[mbrick]

I don't know anyone that would recommend using a ball hone on a 2 stroke cylinder..... yikes.  3 bar hone maybe, or scotchbrite.

The plating looks toast below the exhaust port anyway.  You should send it out to be re-plated.

[turbo dan]

Here's the thing with plating.  The finished surface is hard if properly prepared, as in the final step of the plating process with a diamond hone.  The plating itself is a nickel plating with chunks of silicon carbide dispersed in the matrix.  Nickel is not particularly hard or durable.  When you run a common abrasive hone through the bore you are going to knock the chunks of silicon carbide out of the cylinder wall and embed abrasive particles in.  If you are persistent enough you will remove the plating entirely.  Its just nickel with chunks of silicon carbide.  A diamond hone will cut the chunks of carbide cleanly as opposed to pulling them right out.  That's the only way to do it.

Honing a cylinder as a routine matter or maintenance is a bad idea.  Your rings will seat regardless due to the hardness of the cylinder wall against the soft faced ring.  Honing a worn bore cannot restore it to proper dimensions, same as any bore cast iron, plated, sleeved, etc.  If the cylinder is worn through the cross hatch it is near the end of its service life and should be replated.  A plated bore will last hundreds of hours if taken care of, and all it needs is a enough oil of good quality and good air filtration.  Unless you're running a castor based oil you don't need to bother scrubbing the cylinder wall at all. 

You would be far better off just running a worn cylinder than you would be trying to hone a crosshatch back into it.  You're just taking more material out of an already large bore and as the pictures in the original post show, hones tend to bite into edges around ports.  It is possible that this cylinder would have been serviceable before the honing.  The damage to the plating is asymmetrical, indicating the direction the hone was run, which tells you that it was if nothing else made much worse by the honing.

[digital290]

It's a 2 stroke thats what they do after while.  Just put it back together and ride it.

[turbo dan]

18 minutes ago, digital290 said:

It's a 2 stroke thats what they do after while.  Just put it back together and ride it.

If the guy runs it like that the plating will continue to chip away and the ring will begin to eat into the aluminum at the bottom of the port until it bulges into the port and snags, which gets suddenly much more expensive to fix.  Happens slowly at first, then goes real quick at the end.  Wouldn't recommend it.

[Red Eye]

Did you measure it?  (snap-gauge and micrometer)

[wolfgang123]

dang I never expected this much heat!! 
 

I watched a video on rocky mountain ATV you tube channel for rebuilding a cylinder on a yz250..

 

Did exactly what they did. apparently that was wrong? I haven't had a chance to read everyone's response. But i might just put her back together and see what happens. I have a sneaky feeling she needs more than a top end anyways

 

I am going to more research before just going with it..but we will see

Edited February 8, 2018 by wolfgang123

[wolfgang123]

one more thing, the "grinding marks" are VERY VERY enhanced by the camera flash. 

 

Not even close to looking that severe in person 

[turbo dan]

11 minutes ago, wolfgang123 said:

one more thing, the "grinding marks" are VERY VERY enhanced by the camera flash. 

 

Not even close to looking that severe in person 

The surface finish of the remaining plating is not the main issue.  The aluminum showing under the exhaust port is the fatal wound.