Does anyone "knurle" pistons anymore or that another lost art ?

Piston knurling was mostly done to expand the skirt on old worn pistons for a better fit in the bore...Haven't seen one in years...Some of the knurls would imprint the name of the knurl on the piston skirt....

Originally Posted by rcign

www.angelfire.com/biz/snwvlly/bikes/dnthone.htm

Nice opinion about honing, the problem with it is the author disputed himself, so what are we to believe? I just reringed a 4 cylinder rice burner and put 3000 miles on the engine. It burned a quart of oil every 200-300- miles during this period. So I did a little digging and found out it is impossible to get all the rings cast iron, all manufactures of piston rings have one or more rings chrome plated. Finding this hard to believe, I called Hastings and spoke to an engineer who told me the rings I needed for my 2nd rering had the top compression and oil rings chrome plated and I would have to do an "agressive ball hone to get the rings to seat". The block in this engine is very hard, per the engineer. I ordered the ring set from Hastings and will do as they suggest and see what happens. I also ordered a silicon carbide ball hone. Now as far as our 2 cycle engines, it has been my experience that unhoned cylinders are very hard to start some are near impossible to start but they get better as the engine is run. A friend brought his 180 cc engine for me to check out. this engine had about 50 gallons of fuel run in it. We ran the engine, noted the rpm I then honed the cylinders with a crosshatch, ran the engine and after about 10 ounces of fuel thru it the rpm was checked and there was a 200 rpm increase. And the owner said " my god the compression was way more than before the hone job". So the bottom line is, of course, do what you want or believe when reringing. This opinion is based on building some 100 engines over the last 30 years.

Just a hone Jack, or did you replace the rings too??
I had a similar instance when I plated some aluminum in a cylinder. Took some muriatic acid and cleaned that out, then ran a brake hone through it, rpms came back to original without replacing the rings.

Originally Posted by RTK

Just a hone Jack, or did you replace the rings too??
I had a similar instance when I plated some aluminum in a cylinder. Took some muriatic acid and cleaned that out, then ran a brake hone through it, rpms came back to original without replacing the rings.

If you are asking about the 180cc engine, just honed and used original rings.

Originally Posted by ken crane

the nikasil liners are real hard and you risk chipping the edges of the transfer ports with a ball hone iif you are not careful.

excactly! do not hone a coated cyl. its not needed. just put the new parts in it will seat just fine!

Originally Posted by ken crane

the nikasil liners are real hard and you risk chipping the edges of the transfer ports with a ball hone iif you are not careful.

excactly.do not hone a coated cyl its not needed!! it will chip! and then you got big problems....

Originally Posted by swheaton

excactly.do not hone a coated cyl its not needed!! it will chip! and then you got big problems....

Why do you think it is not ok to hone coated cylinders? and what type of "coating" do you think is on the cylinders? Why does Sachs, Sthil, Homelite Husky, Echo, and all other manufactures HONE the cylinders on their industrial engines. I think people who have opinions on these forums should have a little knowledge of the subject thats being discussed. If you take the cylinder off your gas rc engine, you must hone a crosshatch in the cylindfer in order for the rings to seat, if you do not do this the rings will never seat.

Originally Posted by jack strickland

Why do you think it is not ok to hone coated cylinders? and what type of "coating" do you think is on the cylinders? Why does Sachs, Sthil, Homelite Husky, Echo, and all other manufactures HONE the cylinders on their industrial engines. I think people who have opinions on these forums should have a little knowledge of the subject thats being discussed. If you take the cylinder off your gas rc engine, you must hone a crosshatch in the cylindfer in order for the rings to seat, if you do not do this the rings will never seat.

jack,this should maybe say "if your rc cylinder isnt nikisil or flash coated"as the origonial poster stated it was an evoloution that claims nikisil coating.
some of do know what we are discussing and are not looking to get into a pissing contest so dont take this the wrong way. in most cases any hone short of diamond, all you do is wear the hone as the coating is harder than the hone. most of the article we read a few pages back were related to a 4 cycle engine that used chrome wiper rings to seal oil from the crank case.the part where the author stated all you do is trap sanding compound in the cross hatches could be very true if you dont properly clean after yopu service but that is why after you do hone a cylinder you must always wash it in dawn or a like soap and hot water. i raced ktm enduro motorcycles from 1990- 2005 . theese are the years when the most advanced technology went into racing development in two cycle engines. all cylinders at that time were powervalved reed induction large bore motors. they put up with more torture than any 10 of our engines will ever see in their lifetime.we ingested mud raw water sand and anything else that would get into the air box. 99 out of 100 % of the time the cylinder looked good and the piston skirt was trash. a little soap and water, maybe a scotch brite to clean the carbon that built up where the rings stuck or was worn. a new piston and a couple of cast iron rings and it was as good or better than new. now drop a ball hone into the same cylinder and you can almost be gaurenteed that you will have leaks near the transfer ports ,exhaust bridge or cylinder taper where the balls catch an edge.i also have 16 holes in the 2 v8 300 hp outboards that are hanging off my race boat. those motors work in more he same type of enviorment we fly in with clean air and no air filter. pistin rings wear, leak by.just a re ring clean the block with soap and water re assemble its as good or better than new. all proven by leakdown testing.
what it looks like is the poster that asked us our opinions will need to decide what he feels is the best action and maybe google the subject and get 300 different answers from every expert from snomobile -motorcycle- industrial- boat-and hobby world ! sorry for my rant but i had to.

Well gentlemen, I am glad I brought this up. I was hoping for some good points and discussion and was also reminded in the first couple of posts that the cylinder may be Nikasil coated. Honing will never help it. I would have tried to hone it as I always do with any other internal combustion engine and would have hurt it before helped. I just slapped a new ring on the piston last night and cleaned up the jug. Added some oil and bolted it on. To be certain that the cylinder is indeed Nikasil coated, I will PM Pe. My 450cc race quad has a Nikasil coated cylinder, and when the time comes for a rebuild, a larger bore kit and new cylinder is most likely going to be cheaper than cutting the coating and re applying. It is not cheap. I have investegated the scenario for the quad.

Chainsaw cylinders ARE honed after plating..Chrome plating builds up on sharp edges, you can see this where the sharp edges around the ports a slightly rounded, just enough to take the sharp edges off.....A diamond or Borazon hone is used to SMOOTH theremaining high spots...Without the finish honing the cast iron rings would be worn in short order...If it were possible to plate a cylinder smooth enough there would be no honing necessary...Take a new, never run 2 cycle engine apart and look closely at the bore...It's mirror smooth...The visible marks are below the smooth surface....If you can feel marks with your fingernail it's because the high spots have been smoothed off....With a hone...To keep the rings from being destroyed.....Look at the steel cylinder liner in a new glow engine..Perfectly smooth, no crosshatch....

Originally Posted by ken crane

jack,this should maybe say "if your rc cylinder isnt nikisil or flash coated"as the origonial poster stated it was an evoloution that claims nikisil coating.
some of do know what we are discussing and are not looking to get into a pissing contest so dont take this the wrong way. in most cases any hone short of diamond, all you do is wear the hone as the coating is harder than the hone. most of the article we read a few pages back were related to a 4 cycle engine that used chrome wiper rings to seal oil from the crank case.the part where the author stated all you do is trap sanding compound in the cross hatches could be very true if you dont properly clean after yopu service but that is why after you do hone a cylinder you must always wash it in dawn or a like soap and hot water. i raced ktm enduro motorcycles from 1990- 2005 . theese are the years when the most advanced technology went into racing development in two cycle engines. all cylinders at that time were powervalved reed induction large bore motors. they put up with more torture than any 10 of our engines will ever see in their lifetime.we ingested mud raw water sand and anything else that would get into the air box. 99 out of 100 % of the time the cylinder looked good and the piston skirt was trash. a little soap and water, maybe a scotch brite to clean the carbon that built up where the rings stuck or was worn. a new piston and a couple of cast iron rings and it was as good or better than new. now drop a ball hone into the same cylinder and you can almost be gaurenteed that you will have leaks near the transfer ports ,exhaust bridge or cylinder taper where the balls catch an edge.i also have 16 holes in the 2 v8 300 hp outboards that are hanging off my race boat. those motors work in more he same type of enviorment we fly in with clean air and no air filter. pistin rings wear, leak by.just a re ring clean the block with soap and water re assemble its as good or better than new. all proven by leakdown testing.
what it looks like is the poster that asked us our opinions will need to decide what he feels is the best action and maybe google the subject and get 300 different answers from every expert from snomobile -motorcycle- industrial- boat-and hobby world ! sorry for my rant but i had to.

No problem on ranting, I do it also. the way I see this subject is-- we tend to get off topic a little and compare every type of engine to make the point. Example Ralph says "look in the bore of a glow engine" this has absolutely nothing to do with this discussion. Bottom line If you want your rings to seat, then you must crosshatch the cylinder. If you don't want to do this, then live with the results. I need an answer to this question. Why do EVO and Kroma crosshatch their new engines, and did not crosshatch their engines when starting up? Don't believe me, Just ask Kiwi about this. Kiwi please chime in here.

Originally Posted by rcign

Chainsaw cylinders ARE honed after plating..Chrome plating builds up on sharp edges, you can see this where the sharp edges around the ports a slightly rounded, just enough to take the sharp edges off.....A diamond or Borazon hone is used to SMOOTH theremaining high spots...Without the finish honing the cast iron rings would be worn in short order...If it were possible to plate a cylinder smooth enough there would be no honing necessary...Take a new, never run 2 cycle engine apart and look closely at the bore...It's mirror smooth...The visible marks are below the smooth surface....If you can feel marks with your fingernail it's because the high spots have been smoothed off....With a hone...To keep the rings from being destroyed.....Look at the steel cylinder liner in a new glow engine..Perfectly smooth, no crosshatch....

Your statement about "take a 2 cycle engine apart" etc is not what I have observed on Sachs cylinders, they were crosshatched form/by Sachs.

A bore is a bore is a bore.Some glow engines have rings just like gassers.It's EXACTLY the same..The finish is what's important...a rough finish will wear out the rings in short order since any plating, chrome or Nikasil is harder than the rings.....A chosshatch finish that is not completley smooth will wear the rings...a crosshatch finish that IS smooth retains lube in the low sections...

My Lycoming was not honed when it was rebuilt....

Until recently I was rebuilding one to three engines a day for instant reuse in the field. Honing was not performed in any of them. All of them were "famous maker" engines that were flame flame plated. In every rebuild the engines equalled or exceeded the original performance of the engine and flew for hundreds of hours post rebuild. The most that was done to any of the cylinders was removal of any carbon blow by using a brass rotary brush and kerosene. Over the course of the last year hundeds of engines have been handled this way, with thousands of hours of post rebuild running time that prove the validity of the process.

I know that RCIGN is absolutely correct about how the cylinders are plated. Plating is done after the cylinders were cross honed, not before. The better engines have a second honing process peformed after the plating, as Ralph noted, to take off the high spots and edges. Many Chinese engines do not have the second clean up hone performed and ring wear is extremely fast, and very uneven, along with LOTS of piston skirt and lower cylinder wear. Sometimes their cylinders are actually concentric.