To oil or not oil new cyl and piston

[The Lorax]

Good Article, I always wondered when the 2T would come back, TBH I lost interest in the 4T MX Bikes the cost and complex engines have taken the fun out of it.
That sounds like a version of stratocharging in the Aprilia.

 

[edisto]

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.

I don't believe much breakin in is going to happen either before lube hits those components.

You can't have it both ways Brad! The process of "breaking in" is wear, so you can't be worried about excessive wear if you aren't convinced it isn't going to happen.

Glazing is what stops break in of the rings, and glazing is oxidation of the oil film due to high temperatures. 2-stroke rings simply are not designed to deal with a layer of 2-stroke oil on the cylinder wall...4 stroke rings are.

Another factor to consider is that the rings are forced against the cylinder wall by pressure from the combustion chamber. This requires the chamber to get warm before the serious breaking in starts. If the oil is too thick on the cylinder wall, there will be blow-by, and you won't generate enough pressure against the rings for a proper break in.

Tzed...thanks for the excellent suggestion!

I grew up at my dads garage

I haven't seen any real evidence that you have completed the growing up process.

 

[056kid]

Sounds like more over engineered nonsense to me, the few saws that i have Put rings and or a whole new top in, and a few rings in a few bikes, never have I had problems with blowby, glazing, bad ring seat, low compression, or ANY of the other supposed problems associated with applying a bit of oil while assembling a 2 strokr motor. . .:monkey:

 

[The Lorax]

Sounds like more over engineared nonsence to me, the few saws that i have Put rings and or a whole new top in, and a few rings in a few bikes, never have I had problems with blowby, glazing, bad ring seat, low compression, or ANY of the other suposed problems associated with applying a bit of oil while assembling a 2 strokr motor. . .:monkey:

Yup

 

[edisto]

Sounds like more over engineered nonsense to me, the few saws that i have Put rings and or a whole new top in, and a few rings in a few bikes, never have I had problems with blowby, glazing, bad ring seat, low compression, or ANY of the other supposed problems associated with applying a bit of oil while assembling a 2 strokr motor. . .:monkey:

Let's be clear...we're not talking about the difference between running well and running poorly, we're talking about ok vs. optimal.

"I've always done this and it worked out OK" is not an experiment, because nothing is manipulated. You have no way of evaluating whether the alternative is better or not.

There is plenty of theoretical and empirical information available on breaking in a 2-stroke P&C, and the data are in agreement with the theory. TZed's advice makes a whole lot of sense in light of both. Take it or leave it, but you can't dismiss it on any grounds other than your own opinion.

 

[blsnelling]

You can't have it both ways Brad! The process of "breaking in" is wear, so you can't be worried about excessive wear if you aren't convinced it isn't going to happen.

I was waiting on someone to pick up on that I knew I was kind of contridicting myself when I wrote it, lol. Sometimes, you can argue a topic both ways. I guess this is one of them.

 

[AUSSIE1]

I was always of the belief that glazing was caused through "babying" the engine, which ever that may be, 2t or 4t.
Also I was of the belief that glazing occurred over a reasonable amount of time.
2 stroke rings need a film of oil between themselves and the bore just like a 4 stroke to prevent rapid wear.
I don't see any difference between a 2T ring and a 4T comp ring.
The 4T runs oil control rings due to oil present in the sump.
What happens when oil control rings wear or loose their tension?
What's your thoughts?

 

[edisto]

I was always of the belief that glazing was caused through "babying" the engine, which ever that may be, 2t or 4t.

Yup...it has to be put under load. If you just let it idle, you won't be forcing the rings against the cylinder. WOT for extended periods, however, also will promote glazing. Basically (after heat-cycling) cutting small stuff for a tank or 2, allows you to vary the rpms (which is important), load the engine, and keeps you off of WOT.

Drop a few trees before you swap the P&C or replace the rings, and then use the saw for limbing for a tank (or 2).

 

[romeo]

A National Championship winning tech does not agree with you...


I didn't say put it together dry. I said oil the skirts. You've mistaken me for someone who doesn't know what I'm talking about. I have been building engines for over thirty years.

You are in the mood for a pi$$ing match...I am not.

I stated my opinion, without quoting anyone and countering theirs.

Pi$$ away..... we are done:monkey:

I have to kind of disagree with you on this. For one, how long ago was this. Kawis' went nikisil in the mid 80's. There is no real ring seating time in a chrome bore. I might be able to see the logic on a cast iron sleeve with a race bike since a quick break in will give you what the doc ordered (regular break in time back then was 6 or 7 hours), we never ran the motocross motors long enough to seat a cast bore before we ripped them apart. The chrome bore's held top compression after two minutes of run time. I also know allot of racers were still running cast iron sleeves after the first build in their motors well into the 90's to keep them easily rebuildable.

 

[romeo]

I also think some folks have a misconception of problems with assembly lube. Back when they discovered the baking problems, they were in conjunction with using white lithium grease (not engine oil), which used to be the standard rebuild lube for all motors. I also remember allot of folks using vasoline (petroleum jelly) as assembly lube to avoid the baking problems.

 

[Tzed250]

i have to kind of disagree with you on this. For one, how long ago was this. Kawis' went nikisil in the mid 80's. There is no real ring seating time in a chrome bore. I might be able to see the logic on a cast iron sleeve with a race bike since a quick break in will give you what the doc ordered (regular break in time back then was 6 or 7 hours), we never ran the motocross motors long enough to seat a cast bore before we ripped them apart. The chrome bore's held top compression after two minutes of run time. I also know allot of racers were still running cast iron sleeves after the first build in their motors well into the 90's to keep them easily rebuildable.

1992




.

 

[dingeryote]

1992




.

Chrome hit the KX motors in 1979.

Everyone was scared to death of tossing a cir-clip as it would cost a new Jug.

Stay safe!
Dingeryote

 

[romeo]

Chrome hit the KX motors in 1979.

Everyone was scared to death of tossing a cir-clip as it would cost a new Jug.

Stay safe!
Dingeryote

Allot of the racers didn't take well to the chrome bores because of that reason, I have done a rebuild in between heats before too, a circlip groove in a cylinder could mean no second heat, and no season points unless you had another complete top end ready to go. My bets are on the kawi builder running cast sleeves in his motors which was very common.

 

[Justsaws]

Have any of you ever removed a top end from a greased assembly after five minutes of run time? What did you see?

Straight oil wipers how many seconds(hopefully) of smoking until you believe the engine is clear of excess oil? If you have removed the top end after five minutes of run time what did you see?

When you pull a used top end to take a peek and put it back together would you grease or oil it up?

How many of you run the engine rich for a tank for extra lubrication protection?

Cat mufflers?

 

[romeo]

Have any of you ever removed a top end from a greased assembly after five minutes of run time? What did you see?

Straight oil wipers how many seconds(hopefully) of smoking until you believe the engine is clear of excess oil? If you have removed the top end after five minutes of run time what did you see?

When you pull a used top end to take a peek and put it back together would you grease or oil it up?

How many of you run the engine rich for a tank for extra lubrication protection?

Cat mufflers?

I actually have pulled a cylinder after 5 min's +/- quite a few times. I saw no glazing or buildup. Not greased though, like I said earlier, straight 30W. I also like to run rich mix for the first tank. What ever oil was in the crankcase will blow through fairly quickly after you run it, no more than a few minutes.

As for cat mufflers, those just aren't my forte.

 

[Justsaws]

I actually have pulled a cylinder after 5 min's +/- quite a few times. I saw no glazing or buildup. Not greased though, like I said earlier, straight 30W. I also like to run rich mix for the first tank. What ever oil was in the crankcase will blow through fairly quickly after you run it, no more than a few minutes.

As for cat mufflers, those just aren't my forte.

It has been my experience that a small amounts of oil applied makes no visible difference and is washed away quickly. Small amounts means that you know you put it on but it is not dripping off when resting on a rag. Excessive oil or gear lube wt oils take longer. I have noticed that a liberally oiled set of bearing will seep oil during the cooling of the saw for some time.

Grease is a different story. It can take a while to get the remnants of grease out of the nooks and crannies and while the grease is in there it collects fines and holds them to a surface. It also seeps down during the cooling of the engine into a pool at the bottom of the crankcase. I cannot say that I have noticed any huge problems with small amounts of assembly grease but that it seems to not be needed and the side effects could cause issues. I will say that if I wanted to get some huge false compression numbers that grease could help.

I am not a fan of having something in the crankcase that collects and hold fines. Excessive oil and grease could certainly do that and do not seem to be needed at all.

The engines that were assembled dry worked fine and the only visible difference was some very light scuffing on the pistons that looked like it was caused by contaminants moving through the engine. No visible damage to the cylinder walls or bearings. I was not able to lock one up with a typical starting procedure.

I am going to edit this to say that by dry I mean nothing extra was done beyond installing new parts out of factory box and or bags. No cleaning, no extra lube. I removed the word completely from before the word "dry" as I think it was mis-leading.

I have not seen a 2 cycle oil glazed plated saw cylinder.

 

[mowoodchopper]

You can't have it both ways Brad! The process of "breaking in" is wear, so you can't be worried about excessive wear if you aren't convinced it isn't going to happen.

Glazing is what stops break in of the rings, and glazing is oxidation of the oil film due to high temperatures. 2-stroke rings simply are not designed to deal with a layer of 2-stroke oil on the cylinder wall...4 stroke rings are.

Another factor to consider is that the rings are forced against the cylinder wall by pressure from the combustion chamber. This requires the chamber to get warm before the serious breaking in starts. If the oil is too thick on the cylinder wall, there will be blow-by, and you won't generate enough pressure against the rings for a proper break in.

Tzed...thanks for the excellent suggestion!



I haven't seen any real evidence that you have completed the growing up process.

I also haven't seen any evidence of logic or common sense from
you but I guess you have heard that before! It doesnt seem to be helping!

 

[mowoodchopper]

I actually have pulled a cylinder after 5 min's +/- quite a few times. I saw no glazing or buildup. Not greased though, like I said earlier, straight 30W. I also like to run rich mix for the first tank. What ever oil was in the crankcase will blow through fairly quickly after you run it, no more than a few minutes.

As for cat mufflers, those just aren't my forte.

#1 Romeo, but you could be speaking to the deaf, dumb, and blind .
Its hard communicate with SOME of the DISBELIVERS!

 

[edisto]

I also haven't seen any evidence of logic or common sense from
you but I guess you have heard that before! It doesnt seem to be helping!

Not to worry...literacy is overrated anyway.

 

[dingeryote]

Allot of the racers didn't take well to the chrome bores because of that reason, I have done a rebuild in between heats before too, a circlip groove in a cylinder could mean no second heat, and no season points unless you had another complete top end ready to go. My bets are on the kawi builder running cast sleeves in his motors which was very common.

Romeo,

When Kawi went to the chrome, there were no Iron liners available for years.
There wasn't enough meat to bore out, and press in a custom liner.

When Kawi went to water cooled a few years later, only the KDX stayed AC for a couple years, and still with the chrome liners.

Spare top ends were the rule, but then the Chrome proved to be tougher than anyone figured. Most of the hot spot seize issues went away, and the number of busted rings chewing a groove became rare.

You ran "Heats"? Lemme guess you're in the iron shoe club?

Stay safe!
Dingeryote