To oil or not oil new cyl and piston

[mowoodchopper]

The harm can come from the assembly oil only partially burning and glazing the bore.

With good oil and a light coat there is no chance of that. Even with to much oil in a two stroke its gonna be gone in a few seconds. More of an issue in four strokes and usually from low quality parts or machine work not assembly lube.

 

[tdi-rick]

Holy smoke, or not to smoke. Thanks all for responding or all 2 cents. I think I'll just put a light coat of oil on everything, and put the saw back together.
Another myth or theory is --- don't use synthetic oil for the breakin period, supposedly the rings will never seat. Only use synthetic after the engine has been broken in and the rings seated.
Just another rumor i suppose.
Normally what I do is put a small amount of oil on everything including all the bearings and wrist pin. Get the saw running, turn up the idle and let it sit in the yard or somewhere running for 10 to 15 minutes to help seat the rings. I do not run the saw wide open till this is done. Right or wrong, this is just how I do it. I realize the shops and others don't have the time to do this.

thanks all

jbgorecom

First up I reckon the syn=no break in is an absolute myth.

In the Yamaha 'J' kart class over 20 years ago we used full syn Castrol TTS right from the beginning, and I had one of the top engine builders in Australia at the time.
In the reed and rotary valved classes we used Castrol R30 (full castor, my engine builder, rightly or wrongly reckoned R30 made more power than A747) as those things were revving up towards 20,000RPM then.

Idling for any length of time won't seat rings. The only thing that seats a ring is to put it under load, preferably at low revs to get the combustion gasses into the ring groove and really push the ring against the cylinder wall.

Idling and getting heat into a cylinder isn't a bad thing, but ideally you'd run it up and down the rev range a little and turn off to give it a few heat soak cycles.
I could go into the run in procedure of an old high HP air cooled kart engine, but it isn't really relevant as we were terrified of piston seizures due to the different growth rates of an iron sleeve and cast aluminium piston.

 

[maico490]

With good oil and a light coat there is no chance of that. Even with to much oil in a two stroke its gonna be gone in a few seconds. More of an issue in four strokes and usually from low quality parts or machine work not assembly lube.

Nothing to get worked up over, just what I read and followed.
Volttaire put it better than I can by saying:

"I disapprove of what you say, but I will defend to the death your right to say it"

 

[THALL10326]

What is the best way to install a new cylinder, piston, & rings. Oil the cylinder before installing the piston??? or start the saw with the cylinder dry???
I know some guys on car engines don't oil the cylinders before. This was supposed to seat the rings better.

any help from the big dogs?? (no pun intended)

jbgorecom

Thats a interesting question. I remember when I was at the Stihl factory watching the people assemble engines I don't recall them oiling them down at all. Whether the cylinders were pre-lubed with something before assembly is beyond me. All I seen was engines being assembled and sent down the line. Once the unit was complete it was ran in a test cell, adjusted and sent on. I never seen any oil anywhere on the line but I wasn't searching for it either.

I do know over at the tech center at the factory the engine gets soaked with oil during assembly, I know, I did one at the instructions of the instructor. He handed us a bottle of orange 2-stroke mix oil and said oil it up good.

As for me I've assembled engines both ways, dry and oiled, and really seen no differance. I always oil up all the bearings during assembly though which runs off in the bottom of the engine. I'm sure it gets taken up in the cylinder during start up. I've made a habit of coating the cylinder very very lightly with 2 stroke oil only as my personal perferance. Whether the assembly really needs any oil at all is beyond me. I do know less is better than alot, all the smoke on start up is why I use very little oil during assembly.

 

[mowoodchopper]

Nothing to get worked up over, just what I read and followed.
Volttaire put it better than I can by saying:

"I disapprove of what you say, but I will defend to the death your right to say it"

:agree2: with the last part same goes for me!

 

[blsnelling]

Assy lube is for components that require lube while operating, and would otherwise be dry on start up.

Cylinders and rings on 2 strokes get enough of a coating with the first intake stroke. If they didn't, the darn things wouldn't run very long after sitting for a week.

I'm replying for the sake of discussion, not arguing.

I don't buy your arguement. Your piston, cylinder wall, and rings are dry at startup if you assemble it that way. There's just no way all of those components are coated with the first intake stroke. It takes some time for the oil to migrate to all those surfaces. This is not a pressurized lubricating system. With that philosophy, there's no reason to lube the crank bearings either. It may not take long, but you will be running dry for a short period of time. No?

 

[Hddnis]

Sharing what we've each done and has worked for us is fine.

Seems an awful lot of trouble to try to shoot down how the other guy is doing it, seems in this case both ways work for folks.


Mr. HE

 

[blsnelling]

The idea of only coating the piston skirt kind of intriques me. But it still goes against logic, IMHO. Never again in the life of the engine will the rings and cylinder be dry. I don't believe much breakin in is going to happen either before lube hits those components.

 

[tdi-rick]

I'm replying for the sake of discussion, not arguing.

I don't buy your arguement. Your piston, cylinder wall, and rings are dry at startup if you assemble it that way. There's just no way all of those components are coated with the first intake stroke. It takes some time for the oil to migrate to all those surfaces. This is not a pressurized lubricating system. With that philosophy, there's no reason to lube the crank bearings either. It may not take long, but you will be running dry for a short period of time. No?

Brad, the boys are advocating oiling the piston skirt, just not the ring/s and above, so the cylinder wall will be lubed when the piston is fitted anyway, the way I read it, it just reduces the chances of over oiling.

If you wanted to compromise oil it all with mix. :greenchainsaw:

 

[Tzed250]

The idea of only coating the piston skirt kind of intriques me. But it still goes against logic, IMHO. Never again in the life of the engine will the rings and cylinder be dry. I don't believe much breakin in is going to happen either before lube hits those components.

I am not saying the engine will break in with a dozen strokes.

Never in the life of an engine will it have straight oil on the cylinder walls.

Straight oil and 2% premix are vastly different. As I stated, the purpose of the dry rings is to make sure they touch the cylinder wall, a coating of oil will prevent this.

Rings are meant to run with very little oil. That is why four-strokes have oil scraper rings below the compression rings.

I should have known better than to get in the middle of an oil discussion.

Everyone use the method they like best. I was posting about the one that works for me and other respected two-stroke engine builders.

 

[MS460WOODCHUCK]

Holy sheep!opcorn:

 

[THALL10326]

I am not saying the engine will break in with a dozen strokes.

Never in the life of an engine will it have straight oil on the cylinder walls.

Straight oil and 2% premix are vastly different. As I stated, the purpose of the dry rings is to make sure they touch the cylinder wall, a coating of oil will prevent this.
Rings are meant to run with very little oil. That is why four-strokes have oil scraper rings below the compression rings.

I should have known better than to get in the middle of an oil discussion.

Everyone use the method they like best. I was posting about the one that works for me and other respected two-stroke engine builders.

You got some good points there. I'll be heading down to Stihl 10/13 and I'll ask my buddy there if they lube the cylinders before assembly. I stood and watched those people and I never seen any oil anywhere on the line. Thats not to say they don't or do, only saying I seen many engines get assembled and I don't recall seeing any oil anywhere..

 

[blsnelling]

I should have known better than to get in the middle of an oil discussion.

Everyone use the method they like best. I was posting about the one that works for me and other respected two-stroke engine builders.

I told you I was intrigued with your method. Just not convinced yet. I'm intrigued enough I may try it though.

 

[jbgorecom]

From the stihl 025 service manual (the one I'm putting together)

**before installing the piston into the cylinder
**apply a thin coating of sealant to the outer diameters of the oil seals
**lubricate piston and piston ring with oil

Does not say what oil to use.

So whatever works for you, that's the way to do it.

I'm going to have to come up with something really good to top this post.

jbgorecom (once again , beer's on me)

 

[056kid]

I can say one thing, when good $$ gets spent on P&C's,Im not even gonna dry fit the two before applying some lubricant...

That crap of glazing the bore cause of too much oil? what next?

Bubble blowing reeds caused by a 20:1 mix?

there really are better things to argue about...

 

[AUSSIE1]

I am not saying the engine will break in with a dozen strokes.

Never in the life of an engine will it have straight oil on the cylinder walls.

Straight oil and 2% premix are vastly different. As I stated, the purpose of the dry rings is to make sure they touch the cylinder wall, a coating of oil will prevent this.

Rings are meant to run with very little oil. That is why four-strokes have oil scraper rings below the compression rings.

I should have known better than to get in the middle of an oil discussion.

Everyone use the method they like best. I was posting about the one that works for me and other respected two-stroke engine builders.

Good thing you did get involved.
Nothing wrong with healthy debate.

 

[mowoodchopper]

I am not saying the engine will break in with a dozen strokes.

Never in the life of an engine will it have straight oil on the cylinder walls.

Straight oil and 2% premix are vastly different. As I stated, the purpose of the dry rings is to make sure they touch the cylinder wall, a coating of oil will prevent this.

Rings are meant to run with very little oil. That is why four-strokes have oil scraper rings below the compression rings.

I should have known better than to get in the middle of an oil discussion.

Everyone use the method they like best. I was posting about the one that works for me and other respected two-stroke engine builders.

You just brought up one big diff in a two stroke and a four stroke. I dont know exactly where it fits into this but a four stroke prob is more crucial on break in because the bores are not plated , they rings and bores actually seat together , for instance a worn four stoke will have a ridge in the bore where the rings have worn into the bore. You cant even pull a piston without knocking the ridge down first alot of times. So it prob is gonna be more crucial on the four stroke as far as break in and lube. I do wonder in your method how much of the oil on the skirts gets up top? Its easy to guess but hard to say what actually goes on inside, I use a very light coat of oil on the rings and in the cyl not even enough to make it smoke alot just a thin coat.

 

[dingeryote]

I'm replying for the sake of discussion, not arguing.

I don't buy your arguement. Your piston, cylinder wall, and rings are dry at startup if you assemble it that way. There's just no way all of those components are coated with the first intake stroke. It takes some time for the oil to migrate to all those surfaces. This is not a pressurized lubricating system. With that philosophy, there's no reason to lube the crank bearings either. It may not take long, but you will be running dry for a short period of time. No?

Brad,

Just a wipe around the skirt bottom to get it wet is all.

The rings and cylinder are bone dry untill they make contact with the skirt.

When buttoned down, the cylinder walls above the rings wil be dry.
Chromed, but dry.

Once the crank is turned on starting, the rings will encounter some oil that was transferred by the skirt, and the incoming charge will contact all surfaces. Total distance travelled while not under load and in contact with naked liner is about zero when ya think about it.

The rings contact surface just needs a whisper of film of oil to keep from burnishing the chrome liner.If ya can see a film, it's too thick.

On the big end bearing, after the thing starts, it is only the incoming vapor lubricating, as any volume of significance will be flung off by centrifugal force.

Good 2 stroke oil is amazing stuff, when ya think about how well it works at so little volume.

I probably swapped out 100 sets of rings, and pistons every 4 races back then, and never had an issue except with some bad factory slugs.

Before the Kawasaki Chrome cylinders, I ran all YZ's with Iron Liners and we did splooge things real well with the old Castrol or golden Spectro.
Had a couple get glazed, and busted rings a couple times.

I ain't a pro builder, but when the Team Green Wrench say's "Do this, this is how we set up Wardy and Goat" that's what I do...did...LOL!!

Stay safe!
Dingeryote

 

[056kid]

Brad,

Just a wipe around the skirt bottom to get it wet is all.

The rings and cylinder are bone dry untill they make contact with the skirt.

When buttoned down, the cylinder walls above the rings wil be dry.
Chromed, but dry.

Once the crank is turned on starting, the rings will encounter some oil that was transferred by the skirt, and the incoming charge will contact all surfaces. Total distance travelled while not under load and in contact with naked liner is about zero when ya think about it.

The rings contact surface just needs a whisper of film of oil to keep from burnishing the chrome liner.If ya can see a film, it's too thick.

On the big end bearing, after the thing starts, it is only the incoming vapor lubricating, as any volume of significance will be flung off by centrifugal force.

Good 2 stroke oil is amazing stuff, when ya think about how well it works at so little volume.

I probably swapped out 100 sets of rings, and pistons every 4 races back then, and never had an issue except with some bad factory slugs.

Before the Kawasaki Chrome cylinders, I ran all YZ's with Iron Liners and we did splooge things real well with the old Castrol or golden Spectro.
Had a couple get glazed, and busted rings a couple times.

I ain't a pro builder, but when the Team Green Wrench say's "Do this, this is how we set up Wardy and Goat" that's what I do...did...LOL!!

Stay safe!
Dingeryote

Team Green and saws 101 aint the same ball game.

loader operator used to race, right along side with pastrana, but he gave it up..

back to the point, MX and saws are not the same and you know why...

 

[dingeryote]

Team Green and saws 101 aint the same ball game.

loader operator used to race, right along side with pastrana, but he gave it up..

back to the point, MX and saws are not the same and you know why...

2 Cycles are the same.... mostly.

Saws are catching up to the bikes of the early 80's finally.

Stay safe!
Dingeryote