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Queston about honing a cylinder
#1
P
Phototone
P
Phototone
I have been told that when I replace the rings on a Lawnboy, I should hone the cylinder to help the rings seat. Can somebody give this self-taught Lawnboy mechanic some instruction on how to do this? What type of hone to use, what type of lubricant to use when honing?
#2
L
lewb
L
lewb
I have never replaced a piston or rings in a cylinder. I will be replacing two pistons this fall so I have done some research. I have found that the two or 3 stone expanding hone works better than the round ball type. There are many different sized hones and that you need one that will fit the bore you are working on. The speed of the hone spinning is another issue. Have not gotten much on the ideal rpm only that you do not want to spin too fast. Number of passes is also a concern, less is better. What kind of oil or lubricant is another I do not have any kind of information on. Probably not much help hopefully someone that rebuilds motors will reply.
#3
BlazNT
BlazNT
Lots of YouTube videos on that subject. You really need to watch it to understand it.I have been told that when I replace the rings on a Lawnboy, I should hone the cylinder to help the rings seat. Can somebody give this self-taught Lawnboy mechanic some instruction on how to do this? What type of hone to use, what type of lubricant to use when honing?
#4
J
jp1961
J
jp1961
Hello,
I've never honed the cylinder of a Lawn-boy, but I have rebuilt the engine on a Sears Gamefisher (Tanaka) 3.5 air-cooled outboard. I used a brake cylinder hone and a hand drill. As stated, Youtube does show how to perform honing. The trick is to keep the drill speed slow and move in and out of the cylinder quite rapidly. You shouldn't perform this procedure for that long, maybe a minute or two. You are just deglazing the cylinder and introducing a cross hatch pattern of 30 to 40 or so degrees. Use WD-40 or motor oil as a cutting fluid. Don't stop the hone in the cylinder and remove it, keep the drill spinning as you withdraw it from the bore.
The Outboard ended up with a cold compression test of 103 PSI,,,I guess not too bad for such a small piston. Most weed whacker engines I have only pull about 80 PSI
Jeff
I've never honed the cylinder of a Lawn-boy, but I have rebuilt the engine on a Sears Gamefisher (Tanaka) 3.5 air-cooled outboard. I used a brake cylinder hone and a hand drill. As stated, Youtube does show how to perform honing. The trick is to keep the drill speed slow and move in and out of the cylinder quite rapidly. You shouldn't perform this procedure for that long, maybe a minute or two. You are just deglazing the cylinder and introducing a cross hatch pattern of 30 to 40 or so degrees. Use WD-40 or motor oil as a cutting fluid. Don't stop the hone in the cylinder and remove it, keep the drill spinning as you withdraw it from the bore.
The Outboard ended up with a cold compression test of 103 PSI,,,I guess not too bad for such a small piston. Most weed whacker engines I have only pull about 80 PSI
Jeff
#5
M
motoman
M
motoman
Just a word to interested parties...the honing creates a new surface with a pattern that holds extra oil during new ring break in. I think kerosene is also used. One golden rule from hot rod lore. After honing USE HOT SOAPY WATER AND A SCRUB BRUSH TO THOROUGHLY CLEAN THE BORE OF GRIT. RINSE WITH CLEAN WATER AND WIPE WITH A WHITE RAG. Oil afterward to avoid rust. This is hot rod gospel, I forget the verse...:thumbsup:
#6
R
Rivets
R
Rivets
Motoman hit it on the head before I could. The only thing I would add is I use a ball hone instead of a three leg expanding hone. Easier to control and you don't have to worry about setting stone pressure. Don't use a brush, just a rag, but I also wash it twice. You don't want any leftover grit in you engine. I like a spray can of oil (WD-40, PowerLube, etc.) at the ready to stray down any machined surface ASAP after drying. Compressed air first then the white towel, any dirt on the towel, START OVER.
#7
B
bertsmobile1
B
bertsmobile1
And a quick word on stone grit.
Cast iron barrels with cast iron rigs require a really rough hone 180 grit or coarser.
I do a lot of old Pommie motorcycles and they get 120 stones as bottle brush hones do not go that coarse.
Too fine a hone and the rings will never seat properly.
You will get good compression but blow a smoke screen James Bond would be proud of.
Assemble the rings into the bore with no oil.
A touch of starter fluid or carb cleaner if it needs a little help.
Try not to leave the re-ringed engine idleing for more than a few seconds.
Assemble the engine into the mower start the engine and push it into some long grass they will put a heavy load on the engine.
This builds up pressure behind the rings and they will seal in a few seconds but mow for 10 minutes or so to do the job properly.
Now that the rings have sealed start to play with the carb it will need adjusting if it has been adjusted to compensate for the old worn out rings.
Too many failures come from people spending 20 minutes buggerising around with carb settings with the engine on low idle most of the time happily glazing the bore.
Don't worry if it runs rough , misses, backfires ( a little ) just so long as the throttle is wide open and there is a load on the engine.
The load is really important or the engine overrevs and again glazes the bore.
While mowing it is beneficial to open & close the throttle .
Been breaking in engine this way for 20 years and never had a failure once I changed over to dry installation.
This only applies to castiron rings running on castiron bores
A whole different ball game with steel rings or chrome plated bores
Cast iron barrels with cast iron rigs require a really rough hone 180 grit or coarser.
I do a lot of old Pommie motorcycles and they get 120 stones as bottle brush hones do not go that coarse.
Too fine a hone and the rings will never seat properly.
You will get good compression but blow a smoke screen James Bond would be proud of.
Assemble the rings into the bore with no oil.
A touch of starter fluid or carb cleaner if it needs a little help.
Try not to leave the re-ringed engine idleing for more than a few seconds.
Assemble the engine into the mower start the engine and push it into some long grass they will put a heavy load on the engine.
This builds up pressure behind the rings and they will seal in a few seconds but mow for 10 minutes or so to do the job properly.
Now that the rings have sealed start to play with the carb it will need adjusting if it has been adjusted to compensate for the old worn out rings.
Too many failures come from people spending 20 minutes buggerising around with carb settings with the engine on low idle most of the time happily glazing the bore.
Don't worry if it runs rough , misses, backfires ( a little ) just so long as the throttle is wide open and there is a load on the engine.
The load is really important or the engine overrevs and again glazes the bore.
While mowing it is beneficial to open & close the throttle .
Been breaking in engine this way for 20 years and never had a failure once I changed over to dry installation.
This only applies to castiron rings running on castiron bores
A whole different ball game with steel rings or chrome plated bores
#8
M
motoman
M
motoman
That is good stuff, Bert. Once had a chrome ringed engine which would not seat and blow- by was pints of oil out the crankcase breather. Changed to Grant cast iron rings.
#9
J
jp1961
J
jp1961
Hello,
Not to hijack this thread, but still on the topic of honing. Should you hone cylinders the are chrome or Nakasil plated?
Jeff
Not to hijack this thread, but still on the topic of honing. Should you hone cylinders the are chrome or Nakasil plated?
Jeff
#10
B
bertsmobile1
B
bertsmobile1
Chrome , no
Chrome is micro cracked. It looks like a dried up mud flat and these cracks hold the oil that lubes the bore it is also why you should apply a chrome wax to decorative chrome.
Nickasil is another ball game again.
It is very very very hard and should be used in conjunction with soft rings.
Never had to work on a nikasil engine bore. Only place I come across it is drum brakes which have to be rotary ground back to round.
Chrome is micro cracked. It looks like a dried up mud flat and these cracks hold the oil that lubes the bore it is also why you should apply a chrome wax to decorative chrome.
Nickasil is another ball game again.
It is very very very hard and should be used in conjunction with soft rings.
Never had to work on a nikasil engine bore. Only place I come across it is drum brakes which have to be rotary ground back to round.
#11
timw128
ABSOLUTELY NOT!... if you had a piston seizure, or scuff, wipe the Nik plating down with muriatic acid and mild Scotch Brite pad. Wash with warm water/Tide
solution, blow dry, inspect bore for any Nikasil wear through. If so, you need to send out for re-plate. Millennium Technologies is the best source and they
charge about $200/cyl. Nik plated cylinders use an entirely different piston ring than a steel bore. They also have the proprietary equipment to diamond hone
the cyl bore to a precise dimension, and they don't chatter and chip the plating.
We prefer the steel bore with a specific honing process and ring metallurgy in our Mercury V6 race outboards. Controlling the bore finish=horsepower.
http://www.millennium-tech.net/serviceInfo.php?id=7
Hope this helps.
tim
timw128
Hello,
Not to hijack this thread, but still on the topic of honing. Should you hone cylinders the are chrome or Nakasil plated?
Jeff
ABSOLUTELY NOT!... if you had a piston seizure, or scuff, wipe the Nik plating down with muriatic acid and mild Scotch Brite pad. Wash with warm water/Tide
solution, blow dry, inspect bore for any Nikasil wear through. If so, you need to send out for re-plate. Millennium Technologies is the best source and they
charge about $200/cyl. Nik plated cylinders use an entirely different piston ring than a steel bore. They also have the proprietary equipment to diamond hone
the cyl bore to a precise dimension, and they don't chatter and chip the plating.
We prefer the steel bore with a specific honing process and ring metallurgy in our Mercury V6 race outboards. Controlling the bore finish=horsepower.
http://www.millennium-tech.net/serviceInfo.php?id=7
Hope this helps.
tim
#12
B
bertsmobile1
B
bertsmobile1
learn something new every day.
So they plate nickasil onto the bore ?
Would be interesting to know how that is actually done as once dissolved the nickel, aluminium, silicon & iron should all separate out and having different valiencies should not plate as an alloy.
Are you sure it is plated onto the bore or is it sprayed onto the core before the barrel is cast around it then diamond honed after the core is removed ?
So they plate nickasil onto the bore ?
Would be interesting to know how that is actually done as once dissolved the nickel, aluminium, silicon & iron should all separate out and having different valiencies should not plate as an alloy.
Are you sure it is plated onto the bore or is it sprayed onto the core before the barrel is cast around it then diamond honed after the core is removed ?
#13
M
motoman
M
motoman
Interesting, but a long reach into AC tractor engines with such Porsche technology....:laughing:
#14
timw128
'So they plate nickasil onto the bore ?'..... YES
NSC (Nickel Silicon Carbide) is plated to the cast aluminum cylinder bore- after the bore has been machine established at approx. .006"-.010" over to accommodate standard
plating thickness of .003"-.005" (can be applied to .035" thkns). (Ref: http://www.f1moto.com.au/view/nikasil-plating/51) Diamond honing is implemented to achieve final bore/piston fit.
'Nikasil' is a trademarked electrodeposited lipophilic nickel matrix silicon carbide plating. It was developed by Mahle GmbH around 1966. Mahle piston alloys are recognized as the best
in the world, and are found in hi-perf apps such as Porsche engines, among others.
Steel/Iron liners can also be plated accordingly. There are pros and cons to both a Nikasil cylinder wall and a 'steel', as we call them, cylinder wall. There are trade offs between
thermal transformations and cylinder sealing. It's a complex study in the realm of internal combustion engine design and, perhaps, too complicated of a treatise for discussion
here.
Hope this helps.
tim
timw128
learn something new every day.
So they plate nickasil onto the bore ?
Would be interesting to know how that is actually done as once dissolved the nickel, aluminium, silicon & iron should all separate out and having different valiencies should not plate as an alloy.
Are you sure it is plated onto the bore or is it sprayed onto the core before the barrel is cast around it then diamond honed after the core is removed ?
'So they plate nickasil onto the bore ?'..... YES
NSC (Nickel Silicon Carbide) is plated to the cast aluminum cylinder bore- after the bore has been machine established at approx. .006"-.010" over to accommodate standard
plating thickness of .003"-.005" (can be applied to .035" thkns). (Ref: http://www.f1moto.com.au/view/nikasil-plating/51) Diamond honing is implemented to achieve final bore/piston fit.
'Nikasil' is a trademarked electrodeposited lipophilic nickel matrix silicon carbide plating. It was developed by Mahle GmbH around 1966. Mahle piston alloys are recognized as the best
in the world, and are found in hi-perf apps such as Porsche engines, among others.
Steel/Iron liners can also be plated accordingly. There are pros and cons to both a Nikasil cylinder wall and a 'steel', as we call them, cylinder wall. There are trade offs between
thermal transformations and cylinder sealing. It's a complex study in the realm of internal combustion engine design and, perhaps, too complicated of a treatise for discussion
here.
Hope this helps.
tim
#15
timw128
TRUE THAT! :thumbsup:
timw128
Interesting, but a long reach into AC tractor engines with such Porsche technology....:laughing:
TRUE THAT! :thumbsup:
#16
F
fabricgator
F
fabricgator
I am going to chime in with a little bit of (possibly incomplete) information that I am aware of (or believe to be true and pertinent)
You must cross hatch or hone your cylinders when you replace the piston rings. I was told (informally) that two fold, the newly roughened surface aids in the new rings being seated to the cylinder mating surface. [side bar] If you just replace the brake pads without resurfacing (or glaze breaking) the rotors, the pads will not seat on the rotors and you will only have partial contact, thus less braking ability] So in that sense, if you just install new rings on a glazed and polished cylinder bore, there is not any microscopic rough surface to aid in the wear and break in of the new rings. You may have been better off leaving the old rings in there as they have already been shaped and polished to the current cylinder profile.
Basically, your break in period, is a period of all the parts being worn and polished to perfect the microscopic fit of all the components to one another. If you were to monitor everything that is going on, you would note that compression increases over time of correctly breaking in period, and temperature will slowly decrease as the parts polish and friction decreases.
Remember it is called cross hatching, so while you are spinning the hone, you need to be always moving in and out of the bore. Don't just put a hone stone in there and rotate it quickly without aggressively moving in and out of the bore. Slow to moderate rotation and a balanced in/out movement all the while lubricating to remove particle matter. Think wet sanding a paint surface with fine grit sandpaper. You use the water to keep the cutting surface of the sandpaper from clogging with the dust...
Also, the cross hatching will hold more lubricating oil for the break in period, and assist in carrying the wear metals away (well, this is true in crankcase engines with oil bath and I can imagine somewhat similar in two stroke also)
Which inspires another comment for discussion, in two stroke, use additional oil in fuel for initial break in?
And we are air cooled, I know with aircraft engines, we do not run them much on the ground, (especially with the cowling removed) they need to be flown a certain way that puts the most cooling air across the cylinder fins for cooling (shallow climbs), and shallow descents (powered) descents to avoid shock cooling the cylinders.
If you overheat the cylinders during that break in period of high friction, you run the risk of galling the pistons.
So maybe, we should start a freshly honed cylinder with new rings, run it for an initial period (in tall grass like someone previously posted) but for a limited period and then let it cool off. Then an little longer run with a heavier load, but keeping in mind not to run it too long and getting too hot.
I was told one time to drive it like I stole it, and other said to baby it during break in. I know with aircraft engines during breaking, it is common practice to continually change the power settings so as to not "groove" the engine to being used to just running at one particular power setting...
I apologize for being so long in the finger. I like to learn and teach what I have learned. If I openly run my keyboard, maybe someone will point out where I am thinking wrong...
You must cross hatch or hone your cylinders when you replace the piston rings. I was told (informally) that two fold, the newly roughened surface aids in the new rings being seated to the cylinder mating surface. [side bar] If you just replace the brake pads without resurfacing (or glaze breaking) the rotors, the pads will not seat on the rotors and you will only have partial contact, thus less braking ability] So in that sense, if you just install new rings on a glazed and polished cylinder bore, there is not any microscopic rough surface to aid in the wear and break in of the new rings. You may have been better off leaving the old rings in there as they have already been shaped and polished to the current cylinder profile.
Basically, your break in period, is a period of all the parts being worn and polished to perfect the microscopic fit of all the components to one another. If you were to monitor everything that is going on, you would note that compression increases over time of correctly breaking in period, and temperature will slowly decrease as the parts polish and friction decreases.
Remember it is called cross hatching, so while you are spinning the hone, you need to be always moving in and out of the bore. Don't just put a hone stone in there and rotate it quickly without aggressively moving in and out of the bore. Slow to moderate rotation and a balanced in/out movement all the while lubricating to remove particle matter. Think wet sanding a paint surface with fine grit sandpaper. You use the water to keep the cutting surface of the sandpaper from clogging with the dust...
Also, the cross hatching will hold more lubricating oil for the break in period, and assist in carrying the wear metals away (well, this is true in crankcase engines with oil bath and I can imagine somewhat similar in two stroke also)
Which inspires another comment for discussion, in two stroke, use additional oil in fuel for initial break in?
And we are air cooled, I know with aircraft engines, we do not run them much on the ground, (especially with the cowling removed) they need to be flown a certain way that puts the most cooling air across the cylinder fins for cooling (shallow climbs), and shallow descents (powered) descents to avoid shock cooling the cylinders.
If you overheat the cylinders during that break in period of high friction, you run the risk of galling the pistons.
So maybe, we should start a freshly honed cylinder with new rings, run it for an initial period (in tall grass like someone previously posted) but for a limited period and then let it cool off. Then an little longer run with a heavier load, but keeping in mind not to run it too long and getting too hot.
I was told one time to drive it like I stole it, and other said to baby it during break in. I know with aircraft engines during breaking, it is common practice to continually change the power settings so as to not "groove" the engine to being used to just running at one particular power setting...
I apologize for being so long in the finger. I like to learn and teach what I have learned. If I openly run my keyboard, maybe someone will point out where I am thinking wrong...
#17
J
jp1961
J
jp1961
Is there any definitive way to determine if the cylinder was either chrome or Nikasil plated? I'm assuming (maybe wrongly)a chrome plated cylinder doesn't actually look like a chrome bumper, as a bumper isn't shiney until it gets buffed to a high luster.
Jeff
Jeff
#18
timw128
Jeff, generally speaking, on a Nik plated cylinder you'll notice a small degree of casting porosity- little pockets or voids left behind from off gassing during the casting process.
They do not fill in with the plating operation, hence they can be seen. And actually, they'll retain lubricant. These voids do not affect cylinder sealing in any way.
Every engineering dept. has a tolerant point as to how much voiding is acceptable. On the other hand, a steel/iron liner will appear perfectly smooth- especially after
extended use and the cross hatching has worn smooth. Cylinders in an internal combustion engine do not wear uniformly, due to crank pin forces creating a variable load path
through the con rod, transferring the angular force normal to wrist pin center line. Hence uneven bore wear, to different degrees. For that reason, you may still observe
some cross hatch in the bore at different locations.
There are many more complex dynamics involved than this, though.
Hope this helps.
tim
timw128
Is there any definitive way to determine if the cylinder was either chrome or Nikasil plated? I'm assuming (maybe wrongly)a chrome plated cylinder doesn't actually look like a chrome bumper, as a bumper isn't shiney until it gets buffed to a high luster.
Jeff
Jeff, generally speaking, on a Nik plated cylinder you'll notice a small degree of casting porosity- little pockets or voids left behind from off gassing during the casting process.
They do not fill in with the plating operation, hence they can be seen. And actually, they'll retain lubricant. These voids do not affect cylinder sealing in any way.
Every engineering dept. has a tolerant point as to how much voiding is acceptable. On the other hand, a steel/iron liner will appear perfectly smooth- especially after
extended use and the cross hatching has worn smooth. Cylinders in an internal combustion engine do not wear uniformly, due to crank pin forces creating a variable load path
through the con rod, transferring the angular force normal to wrist pin center line. Hence uneven bore wear, to different degrees. For that reason, you may still observe
some cross hatch in the bore at different locations.
There are many more complex dynamics involved than this, though.
Hope this helps.
tim
#19
B
bertsmobile1
Arrrrh,
the old two countries divided by a common language strikes again.
Nikasil was the registered trade name for a series of Nickel, Aluminium, Silicon alloyed cast irons dating back to the late 1800's
I can see where the new name come from because they form nickel-silicon carbides which makes them hard as hell. They also form Nickel-Aluminium -Silicides which does the same as the Aluminium Silicides in the 13% Si controlled expansion alloys used for pistons.
Nikasil was developed for cannon barrels so it is high temperature tollerant , high pressure stable , not reactive, abrasion resistant . Thus the fledging auto industry has a perfect alloy for brake drums when they developed the internal expanding brake.
It was also used for cylinder sleeves in wet sleeves aero engines ,motorcycle brake drums with intergral sprockets , excavator teeth , dozer blade tips and latter disc brake rotors.
That out of the way, I seriously doubt there would be any casting voids in a modern pressure die cast cylinder as the aluminium is degassed with chlorine prior to pouring or you end up with the infamous "growing castings" which kept cast iron being used for pistons right up till the 1940's and the whole point in pressure die casting is to force feed the solidifing casting to prevent the formation of shrinkage voids.
You could however etch the machined bore with hydro flouric acid which will dissolve some of the exposed silicon without touching the aluminium thus maintaining the overall bore dimensions prior to plating.
If you are involved in the process you can check because a casting void will have a very smooth rounded almost glass looking surface where as the etched holes will have a flat sided hole with sharp edges.
B
bertsmobile1
Jeff, generally speaking, on a Nik plated cylinder you'll notice a small degree of casting porosity- little pockets or voids left behind from off gassing during the casting process.
They do not fill in with the plating operation, hence they can be seen. And actually, they'll retain lubricant. These voids do not affect cylinder sealing in any way.
Every engineering dept. has a tolerant point as to how much voiding is acceptable. On the other hand, a steel/iron liner will appear perfectly smooth- especially after
extended use and the cross hatching has worn smooth. Cylinders in an internal combustion engine do not wear uniformly, due to crank pin forces creating a variable load path
through the con rod, transferring the angular force normal to wrist pin center line. Hence uneven bore wear, to different degrees. For that reason, you may still observe
some cross hatch in the bore at different locations.
There are many more complex dynamics involved than this, though.
Hope this helps.
tim
Arrrrh,
the old two countries divided by a common language strikes again.
Nikasil was the registered trade name for a series of Nickel, Aluminium, Silicon alloyed cast irons dating back to the late 1800's
I can see where the new name come from because they form nickel-silicon carbides which makes them hard as hell. They also form Nickel-Aluminium -Silicides which does the same as the Aluminium Silicides in the 13% Si controlled expansion alloys used for pistons.
Nikasil was developed for cannon barrels so it is high temperature tollerant , high pressure stable , not reactive, abrasion resistant . Thus the fledging auto industry has a perfect alloy for brake drums when they developed the internal expanding brake.
It was also used for cylinder sleeves in wet sleeves aero engines ,motorcycle brake drums with intergral sprockets , excavator teeth , dozer blade tips and latter disc brake rotors.
That out of the way, I seriously doubt there would be any casting voids in a modern pressure die cast cylinder as the aluminium is degassed with chlorine prior to pouring or you end up with the infamous "growing castings" which kept cast iron being used for pistons right up till the 1940's and the whole point in pressure die casting is to force feed the solidifing casting to prevent the formation of shrinkage voids.
You could however etch the machined bore with hydro flouric acid which will dissolve some of the exposed silicon without touching the aluminium thus maintaining the overall bore dimensions prior to plating.
If you are involved in the process you can check because a casting void will have a very smooth rounded almost glass looking surface where as the etched holes will have a flat sided hole with sharp edges.
#20
B
bertsmobile1
so what do you think the piston rings do ?
Chrome bores are shinny and slightly blue in appearence
Steel bores will also be shinny but slightly green in appearence.
cast iron will be shinny and grey looking
B
bertsmobile1
Is there any definitive way to determine if the cylinder was either chrome or Nikasil plated? I'm assuming (maybe wrongly)a chrome plated cylinder doesn't actually look like a chrome bumper, as a bumper isn't shiney until it gets buffed to a high luster.
Jeff
so what do you think the piston rings do ?
Chrome bores are shinny and slightly blue in appearence
Steel bores will also be shinny but slightly green in appearence.
cast iron will be shinny and grey looking
#21
B
bertsmobile1
Not far off, not meaning to sound patronising
B
bertsmobile1
I am going to chime in with a little bit of (possibly incomplete) information that I am aware of (or believe to be true and pertinent)
You must cross hatch or hone your cylinders when you replace the piston rings. I was told (informally) that two fold, the newly roughened surface aids in the new rings being seated to the cylinder mating surface. [side bar]
Yes the bore is not perfect round and neither are the rings so they wear into each other.
If you just replace the brake pads without resurfacing (or glaze breaking) the rotors, the pads will not seat on the rotors and you will only have partial contact, thus less braking ability]
No wrong a myth circulated by owners and makers of disc grinding machines. The amount of clamping pressure applied by the brake piston is orders of magnitude higher than the force applied by rings to a bore.
Piston rings also remove a significant amount of heat from the piston to the cylinder wall
So in that sense, if you just install new rings on a glazed and polished cylinder bore, there is not any microscopic rough surface to aid in the wear and break in of the new rings. You may have been better off leaving the old rings in there as they have already been shaped and polished to the current cylinder profile.
Sort of true , if the rings have worn too thin, then they are too thin and you run the risk of them breaking up
Basically, your break in period, is a period of all the parts being worn and polished to perfect the microscopic fit of all the components to one another. If you were to monitor everything that is going on, you would note that compression increases over time of correctly breaking in period, and temperature will slowly decrease as the parts polish and friction decreases.
Correct
Remember it is called cross hatching, so while you are spinning the hone, you need to be always moving in and out of the bore. Don't just put a hone stone in there and rotate it quickly without aggressively moving in and out of the bore. Slow to moderate rotation and a balanced in/out movement all the while lubricating to remove particle matter. Think wet sanding a paint surface with fine grit sandpaper. You use the water to keep the cutting surface of the sandpaper from clogging with the dust...
Also, the cross hatching will hold more lubricating oil for the break in period, and assist in carrying the wear metals away (well, this is true in crankcase engines with oil bath and I can imagine somewhat similar in two stroke also)
No, you don't want any oil in there which is why you install rings dry. Initial wear in particles are sent to the crank by blow by and you run a new engine rich to help wash the bores.
Which inspires another comment for discussion, in two stroke, use additional oil in fuel for initial break in?
No same reason, actually I break in two strokes with a very lean mix. Fuel alone will provide sufficient lube for the big & little ends for a long while and a little squirt of strait oil directly into the crank will keep the mains happy.
And we are air cooled, I know with aircraft engines, we do not run them much on the ground, (especially with the cowling removed) they need to be flown a certain way that puts the most cooling air across the cylinder fins for cooling (shallow climbs), and shallow descents (powered) descents to avoid shock cooling the cylinders.
If you overheat the cylinders during that break in period of high friction, you run the risk of galling the pistons.
Galling is the wrong term but you do get metal to metal contact which will abrade the piston and deposit aluminium on the bore
So maybe, we should start a freshly honed cylinder with new rings, run it for an initial period (in tall grass like someone previously posted) but for a limited period and then let it cool off. Then an little longer run with a heavier load, but keeping in mind not to run it too long and getting too hot.
Not allowing the engine to overheat is a good idea however, heavy loading to develope maximum pressure on the rings is the go then back off to reduce the load allowing the debris to be removed then heavy contact again.
After 5 minutes the rings have seated & worn in, after that you are worried about everything else setteling down
I was told one time to drive it like I stole it,
This is to bed in the rings
and other said to baby it during break in.
This is for fully rebuilt engines where bearing and bushes have to stettle into place thrust washers have to position themselves, crankcases have to heat up, expand then contract to align itself in its bearing / bushings, cam followers have to break in etc etc etc.
I know with aircraft engines during breaking, it is common practice to continually change the power settings so as to not "groove" the engine to being used to just running at one particular power setting...
yes proper run in technique for any piston engine
I apologize for being so long in the finger. I like to learn and teach what I have learned. If I openly run my keyboard, maybe someone will point out where I am thinking wrong...
Not far off, not meaning to sound patronising
#22
J
jp1961
J
jp1961
Thanks Bertsmobile1,
Yeah, two old countries separated buy the same language and a very large pond,,,lol. Your input is appreciated.
Jeff
Yeah, two old countries separated buy the same language and a very large pond,,,lol. Your input is appreciated.
Jeff
#23
timw128
Highly incorrect statement. A simple look at Mercury Marine V6 2 cycle engine blocks from the 1980's forward will clearly remove any of your doubt.
Of further note, your statement regarding Nikasil is also questionable- https://en.wikipedia.org/wiki/Nikasil
timw128
... I seriously doubt there would be any casting voids in a modern pressure die cast cylinder...
Highly incorrect statement. A simple look at Mercury Marine V6 2 cycle engine blocks from the 1980's forward will clearly remove any of your doubt.
Of further note, your statement regarding Nikasil is also questionable- https://en.wikipedia.org/wiki/Nikasil
#24
B
bertsmobile1
B
bertsmobile1
Sorry Tim,
But an entry in Wickipedia does not cut the mustard.
Google "Heat Resistant Cast Irons" and you should come up with foundries casting,
Nickasil ( Ni-Al- Si )
Nicrosil ( Ni-Cr-Si )
Nimosil ( Ni-Mo-Si )
particularly in the UK
BSA held the patient for some of the alloys back in the 60's before they were asset stripped by Manganeese Bronze Ltd.
And a trade name for an alloy can also be used as a trade name for a plated coating as they are not the same thing.
You will find their chemical compositions and mechanical properties on pages 404-406 of the American Society of Metals Handbook volume 1 Properties & Selection of Metals
Also in Volume 7 Atlas of Microstructures
AS for mercury V 6 blocks you have me at a dissadvantage here I have never seen one,
OTOH I have cast around 1000 tons of finished Al castings and made about 60 tons of secondary foundry ingot per week for 5 years.
There is virtually no way to create micro pores in a casting without making a substantially inferriour casting.
Hydrogen is extreamly soluible in molten aluminium and almost all gas porosity will be due to hydrogen.
Because hydrogen atoms are so small they travel quite easily through the solid metal lattice and when 2 hydrogen atoms come together they immediately for a hydrogen molecule.
The hydrogen molecule is substantially bigger and forces the layers of aluminium atoms apart,
the net result of this is the item grows, gets physically bigger and was the chief reason for a lot of engines using heavy cast iron pistons because the aluminium ones expanded and siezed in the bores.
This expansion is perminant and untill a method of scouring the hydrogen out was found limited the developement of alloy pistoned engines till chlorohexamine was found to be efective and it is still used today, although chlorine gas delivered through a titanium lance is a lot more effective.
The only other way to have pores is to super heat the alloy then short poor so there is not enough molten metal to accomodate for the volume contraction from liquid to solid but this would not happen at a core because the melt solidifies from the outside in, not the inside out although with dendritic modification by innoculation combined with ultrasonic disruptions you can get almost equal rates of grain growth inside out & outside in but as far as I know this was only used to facilitate the pouring of larger cross section rolling & extrusion billets.
To get a consistant and equally dispersed surface porosity on the face of the bore it would have to be done chemically after casting.
You do get porosity in castings when using metal moulds, and that is a defect that happens till the surface temperature of the mould gets up to working temperature due to excess chilling at the mould surface.
You also get massive chill grains so the first few casting usually go back into the pot.
If you can explain how you get micro pores only on the bore , controlled so they are uniformly distributed and do not extend all the way through to the water jacket then I am all ears.
But an entry in Wickipedia does not cut the mustard.
Google "Heat Resistant Cast Irons" and you should come up with foundries casting,
Nickasil ( Ni-Al- Si )
Nicrosil ( Ni-Cr-Si )
Nimosil ( Ni-Mo-Si )
particularly in the UK
BSA held the patient for some of the alloys back in the 60's before they were asset stripped by Manganeese Bronze Ltd.
And a trade name for an alloy can also be used as a trade name for a plated coating as they are not the same thing.
You will find their chemical compositions and mechanical properties on pages 404-406 of the American Society of Metals Handbook volume 1 Properties & Selection of Metals
Also in Volume 7 Atlas of Microstructures
AS for mercury V 6 blocks you have me at a dissadvantage here I have never seen one,
OTOH I have cast around 1000 tons of finished Al castings and made about 60 tons of secondary foundry ingot per week for 5 years.
There is virtually no way to create micro pores in a casting without making a substantially inferriour casting.
Hydrogen is extreamly soluible in molten aluminium and almost all gas porosity will be due to hydrogen.
Because hydrogen atoms are so small they travel quite easily through the solid metal lattice and when 2 hydrogen atoms come together they immediately for a hydrogen molecule.
The hydrogen molecule is substantially bigger and forces the layers of aluminium atoms apart,
the net result of this is the item grows, gets physically bigger and was the chief reason for a lot of engines using heavy cast iron pistons because the aluminium ones expanded and siezed in the bores.
This expansion is perminant and untill a method of scouring the hydrogen out was found limited the developement of alloy pistoned engines till chlorohexamine was found to be efective and it is still used today, although chlorine gas delivered through a titanium lance is a lot more effective.
The only other way to have pores is to super heat the alloy then short poor so there is not enough molten metal to accomodate for the volume contraction from liquid to solid but this would not happen at a core because the melt solidifies from the outside in, not the inside out although with dendritic modification by innoculation combined with ultrasonic disruptions you can get almost equal rates of grain growth inside out & outside in but as far as I know this was only used to facilitate the pouring of larger cross section rolling & extrusion billets.
To get a consistant and equally dispersed surface porosity on the face of the bore it would have to be done chemically after casting.
You do get porosity in castings when using metal moulds, and that is a defect that happens till the surface temperature of the mould gets up to working temperature due to excess chilling at the mould surface.
You also get massive chill grains so the first few casting usually go back into the pot.
If you can explain how you get micro pores only on the bore , controlled so they are uniformly distributed and do not extend all the way through to the water jacket then I am all ears.
#25
F
fabricgator
Thank you, I pick up some of this (previously posted beliefs) stuff through osmosis and contact in industry and some of it I draw my own conclusions. This is why I threw this out there so I could be either corrected or confirmed. Thank you for taking the time to straighten these belief's out. Your input only enhances my knowledge base.
I am also learning quite a lot from you and Tim's discussion on metallurgy, casting and plating. This is why I love the internet. I am continually growing and enhancing my knowledge base.
Thank you all.
F
fabricgator
Not far off, not meaning to sound patronising
Thank you, I pick up some of this (previously posted beliefs) stuff through osmosis and contact in industry and some of it I draw my own conclusions. This is why I threw this out there so I could be either corrected or confirmed. Thank you for taking the time to straighten these belief's out. Your input only enhances my knowledge base.
I am also learning quite a lot from you and Tim's discussion on metallurgy, casting and plating. This is why I love the internet. I am continually growing and enhancing my knowledge base.
Thank you all.
#26
J
jp1961
J
jp1961
Hi All,
Nikasil plated cylinders may be more common than you think. The Zenoah G-20 model airplane engine has a Nikasil plated cylinder.http://www.horizonhobby.com/product...e-engines-15042--1/zp-20cc-gas-engine-zenep20
Click the 'specs' tab once the screen comes up.
Jeff
Nikasil plated cylinders may be more common than you think. The Zenoah G-20 model airplane engine has a Nikasil plated cylinder.http://www.horizonhobby.com/product...e-engines-15042--1/zp-20cc-gas-engine-zenep20
Click the 'specs' tab once the screen comes up.
Jeff
#27
M
motoman
M
motoman
An interesting thread. I would like to hear more from the 2 stroke guys who (?had) hinted extra hard bores are used. Also ,like so many threads here, there is an opportunity for forum people to educate. There are many who read this stuff who wished they knew more about the unstated assumptions in many statements.
So maybe start with a primer on how piston rings work....
How many think sealing depends upon the spring affect of the compression rings? Like, dude, your have to compress them to get them into the bore?
How do oil rings work and what are they supposed to do?
What is a piston land?
Are there basic clearances and dimensions which must be met when installing rings?
Should bores be perfect or is taper , out-of-round ok? How about top ridges?
This can all be dug out of basic literature, but maybe some discussion is worthwhile?
So maybe start with a primer on how piston rings work....
How many think sealing depends upon the spring affect of the compression rings? Like, dude, your have to compress them to get them into the bore?
How do oil rings work and what are they supposed to do?
What is a piston land?
Are there basic clearances and dimensions which must be met when installing rings?
Should bores be perfect or is taper , out-of-round ok? How about top ridges?
This can all be dug out of basic literature, but maybe some discussion is worthwhile?
#28
javjacob
javjacob
Out of curiosity is it possible to Nikisil plate a lawn boy cylinder?
#29
J
jp1961
J
jp1961
You could probably have any cylinder plated, but then you'd need a smaller piston and rings. Were Lawn-Boy cylinders ever available oversized? Some manufacturers offered oversized pistons to allow for boring to remove scoring, out of round, etc.
I have a Bridgeport with a boring head and could accurately oversize the bore, but I would need to know how thick the Nikasil plating would end up to return the bore to factory specs.
Jeff
I have a Bridgeport with a boring head and could accurately oversize the bore, but I would need to know how thick the Nikasil plating would end up to return the bore to factory specs.
Jeff
#30
robinb66
robinb66
Also it may be worthy to note that when honing a cylinder or at least making the decision too cast iron cylinders are pretty much ok but if it is a aluminum cylinder with no iron sleeve then at most just run a deglazer a couple of times and don't hone it!
#31
J
jp1961
J
jp1961
Hello,
There is a local company (Labarons power sports in Almont MI - labaronspowersports.com) that offers Nikasil re-plating services. I will call them tomorrow to ask them if it is possible to plate a Lawn-Boy engine. Seems like you'd want to plate a Lawn-Boy engine that has a separate cylinder head like the Duraforce, but it may be possible to plate a jug style engine like the D series. I have an old Duraforce engine, that I could use as a guinea pig. Hmmmm sounds like I've found my next 'winter project',,,lol.
If feasible, sounds like a way to restore an engine, where the cylinder is no longer available from Toro.
Jeff
There is a local company (Labarons power sports in Almont MI - labaronspowersports.com) that offers Nikasil re-plating services. I will call them tomorrow to ask them if it is possible to plate a Lawn-Boy engine. Seems like you'd want to plate a Lawn-Boy engine that has a separate cylinder head like the Duraforce, but it may be possible to plate a jug style engine like the D series. I have an old Duraforce engine, that I could use as a guinea pig. Hmmmm sounds like I've found my next 'winter project',,,lol.
If feasible, sounds like a way to restore an engine, where the cylinder is no longer available from Toro.
Jeff
#32
J
jp1961
J
jp1961
Hi All,
I called Labaron power sports, they use Millennium Technologies (out of WI) for the actual plating, so I called them. The tech said any cylinder (aluminum or steel sleeved) can be plated, but can't be damaged. He said the plating is about .004 to .005" thick, so you would have to bore out the cylinder that much. The process takes 7 to 10 business days and the cost is 209.95. They diamond hone the cylinder after plating. He did say you have to use chrome moly rings with this plating. I'm not sure what standard Lawn-Boy rings are made from.
So there you have it,,,be the first kid on your block with a Nikasil plated Duraforce,,,lol.
Jeff
I called Labaron power sports, they use Millennium Technologies (out of WI) for the actual plating, so I called them. The tech said any cylinder (aluminum or steel sleeved) can be plated, but can't be damaged. He said the plating is about .004 to .005" thick, so you would have to bore out the cylinder that much. The process takes 7 to 10 business days and the cost is 209.95. They diamond hone the cylinder after plating. He did say you have to use chrome moly rings with this plating. I'm not sure what standard Lawn-Boy rings are made from.
So there you have it,,,be the first kid on your block with a Nikasil plated Duraforce,,,lol.
Jeff
#33
javjacob
javjacob
Thanks for finding that out for us! I wonder if it can be done to a F engine?
Then the next thing would be finding chrome rings. Is it chrome or chromoly?
Then the next thing would be finding chrome rings. Is it chrome or chromoly?
#34
J
jp1961
J
jp1961
You're welcome. The tech said chrome moly, not chrome. Standard iron rings would probably wear out very fast against the Nikasil plating. I see no reason why an F cylinder couldn't be plated, remember though you'd need to have the cylinder bored out about .005".
Jeff
Jeff
#35
javjacob
javjacob
I guess the hard part will be finding chromoly rings. If I can find a set I would think about doing it since I have a F engine short block I am going to tear down and rebuild sometime in the future. Just depends on the condition of the cylinder. I would imagine a F engine with a Nikisil cylinder and chromoly rings would never wear out.
#36
F
fabricgator
F
fabricgator
There is another plating technology (of at least brand name) that I have heard in aviation called Cermanil like ceramic.
I would think that Millennium would mill the bore the 5 thou, build it up with deposit plating and then cut it true to size. A one stop cylinder shop.
We also have Millennium brand cylinders in aviation. I wonder if it is the same outfit?
It is not uncommon for the Millennium cylinder to pass compression test beyond wildest dreams. My first time, I got another technician to find out what I was doing wrong to get so high a differential pressure reading (leak down compression test)
I would think that Millennium would mill the bore the 5 thou, build it up with deposit plating and then cut it true to size. A one stop cylinder shop.
We also have Millennium brand cylinders in aviation. I wonder if it is the same outfit?
It is not uncommon for the Millennium cylinder to pass compression test beyond wildest dreams. My first time, I got another technician to find out what I was doing wrong to get so high a differential pressure reading (leak down compression test)
#37
F
fabricgator
F
fabricgator
A few posts back, there was a statement about rings.
Just a little knowledge nugget for some.
When we install new rings on and aircraft engine, there is a procedure about filing the ring gap. We put the individual ring (lets say the number one [or top]) into the cylinder bore and use the piston to push them in to the place where they would be at TDC if wrapped around the piston. Then we slide the piston out and use a feeler gauge to check that ring's gap.
We file fit to a engine manufacturer specification. so that when the assembled engine is at operating temperature, that the gap is just right. Then we repeat for each ring, keeping track of each rings intended position and orientation.
We don't want the gap so big that it is a large passage for pressure to escape, nor do we want it so tight that when the engine heats up and the individual metal parts expand, that the gap closes too tight and possibly applies mechanical pressure to the ring and/or cylinder walls.
In spec is just right.
I've not done a mower nor a lawnboy, but I'd imagine there is a procedure similar to this.
I have a dream, a dream of a home built, scale Junkers_JU-390 or a Focke-Wulf Ta 400 two seat airplane that has six air cooled lawnboy engines powering it...
My friends think I am crazy.
Just a little knowledge nugget for some.
When we install new rings on and aircraft engine, there is a procedure about filing the ring gap. We put the individual ring (lets say the number one [or top]) into the cylinder bore and use the piston to push them in to the place where they would be at TDC if wrapped around the piston. Then we slide the piston out and use a feeler gauge to check that ring's gap.
We file fit to a engine manufacturer specification. so that when the assembled engine is at operating temperature, that the gap is just right. Then we repeat for each ring, keeping track of each rings intended position and orientation.
We don't want the gap so big that it is a large passage for pressure to escape, nor do we want it so tight that when the engine heats up and the individual metal parts expand, that the gap closes too tight and possibly applies mechanical pressure to the ring and/or cylinder walls.
In spec is just right.
I've not done a mower nor a lawnboy, but I'd imagine there is a procedure similar to this.
I have a dream, a dream of a home built, scale Junkers_JU-390 or a Focke-Wulf Ta 400 two seat airplane that has six air cooled lawnboy engines powering it...
My friends think I am crazy.
#38
javjacob
javjacob
I like that idea lol I have a dream of a garden tractor with a detuned triple cylinder 2 stroke snowmobile motor powering it.A few posts back, there was a statement about rings.
Just a little knowledge nugget for some.
When we install new rings on and aircraft engine, there is a procedure about filing the ring gap. We put the individual ring (lets say the number one [or top]) into the cylinder bore and use the piston to push them in to the place where they would be at TDC if wrapped around the piston. Then we slide the piston out and use a feeler gauge to check that ring's gap.
We file fit to a engine manufacturer specification. so that when the assembled engine is at operating temperature, that the gap is just right. Then we repeat for each ring, keeping track of each rings intended position and orientation.
We don't want the gap so big that it is a large passage for pressure to escape, nor do we want it so tight that when the engine heats up and the individual metal parts expand, that the gap closes too tight and possibly applies mechanical pressure to the ring and/or cylinder walls.
In spec is just right.
I've not done a mower nor a lawnboy, but I'd imagine there is a procedure similar to this.
I have a dream, a dream of a home built, scale Junkers_JU-390 or a Focke-Wulf Ta 400 two seat airplane that has six air cooled lawnboy engines powering it...
My friends think I am crazy.