Topic: Idiot forgot to stagger the rings

[Curt2005]

First of all, I am that idiot.

Just finished putting rings on my '73 cb500 (no. 4 rings were stuck good and tight). Followed the manual to the letter (almost, ugh) and now have it 99% back together. Carbs on, just need to hook all the cables back up. Woke up in the middle of the night with the dread that I can't remember staggering the rings. I want to say I did, but damn it I can't remember. I haven't started it back up yet, so......what do I do?

Stop now and tear it all back down to confirm or proceed on forward and check compression after its broken back in to see where they stand?   And then need another set of rings...

Side question, my thought was that a compression test on freshly honed cylinders and new rings wouldn't tell me much at this point.  Am I correct?

And to sum up, I am an idiot...

[Gordon]

The rings start moving around as soon as the pistons start moving in the cylinders, so I wouldn't worry about it.  And, no, a compression test on freshly-honed cylinders with new rings won't tell you much, other than the fact that you have less than perfect compression, which is to be expected with new rings and a hone. 

[trueblue]

The rings start moving around as soon as the pistons start moving in the cylinders, so I wouldn't worry about it.  And, no, a compression test on freshly-honed cylinders with new rings won't tell you much, other than the fact that you have less than perfect compression, which is to be expected with new rings and a hone. 

Yeah what he said ^^^^^^^^^

[Trevor from Warragul]

If you check your plugs every day I swear that once in a while you'll find lots of oil on one of them.  I reckon this happens when all the rings naturally align & let oil through!

Trevor

[killersoundz]

Yup, don't worry about it man the rings will move around on their own. Your compression will be fine, these motors within the specs will make enough compression to burn with just one friggin ring basically lol

[luap]

arnt the rings all offest more to keep the piston straight in the cylinder, thought I read that somewhere

[Joe]

I have nothing to add, other that I too am an idiot.  I'm in the process of rebuilding my top end for the first time on my bike, and I can relate to the anxiety you're experiencing for sure.  If it doesn't start I'm probably gonna cry like a big baby with a poopy diaper

[Curt2005]

Thanks everyone!!  On to the next worry!

[Gordon]

I have nothing to add, other that I too am an idiot.  I'm in the process of rebuilding my top end for the first time on my bike, and I can relate to the anxiety you're experiencing for sure.  If it doesn't start I'm probably gonna cry like a big baby with a poopy diaper

Don't worry too much.  If/when it doesn't start it's probably a wiring issue.  Change your diaper and the switch the spark plug wires around to where they should be.

[trueblue]

If the location of the rings were that critical they would be pinned so they can't turn, ***Brain fart occured here***

[Raul CB750K1]

If the location of the rings were that critical they would be pinned so they can't turn, a lot of 2 strokes have a pin in the ring gap because they rely on having compression on both sides of the pistons to run.

If I'm not wrong, the reason for that is to avoid the ring gap moving to the cylinder opening where the mixture is sucked in -or exhaust blown off-, where the ring gap could jam into the opening with disastrous results.


I don't really think that the rings move that much. Downward and upward pressures are so big that the rings have a lot of friction against the piston groove, and furthermore, the movement is up-and-down, so no considerable side-to-side forces on the rings, and if there are, the friction against the piston groove should avoid the side-to-side movement. Furthermore, the movement is reciprocicating, so if the ring tends to turn when the piston goes down, it should tern to turn the opposite direction when the piston goes up, giving a total side movement of almost 0....


What would I do if I were you..... it depends on how much your peace of mind is worth. Opening the engine again will mean time and new gaskets, if you can afford that, go for it. I have been through what you are going now many times. What I do is take lots of pictures during reassembly, so when I'm in doubt it is easy to check whether that o-ring is there or whether that piston pin circlip was installed....

[trueblue]

Raul, you would be surprised with how much they move, I'm a heavy equipment/diesel mechanic and where I work we also have an engine shop and my boss also owns a civil works buisness, I see a lot of engines in pieces and for the record not all 2 strokes have the pins but these are usually the little crappy ones.  I have had a couple of... umm errors in judgement that have required disassembling the engines again shortly after running and trust me the rings move while the engine is running, most engines we strip down have at least one cylinder with all the rings lined up.  There was one job that sticks in my mind rather well, one of our trucks which ran great and never burned any oil had an oil pump failure and spun a big end bearing, when we disassembled the engine the rings on all but one piston were lined up, if it didn't affect an engine that runs 22:1 compression it won't worry one that only has 9:1, so basically the ring gaps don't matter a sh!t where they are because they will move anyway. 

[LesterPiglet]

Now I just learned something. I thought all pistons had the pins for locating the rings.

[Raul CB750K1]

Raul, you would be surprised with how much they move, I'm a heavy equipment/diesel mechanic and where I work we also have an engine shop and my boss also owns a civil works buisness, I see a lot of engines in pieces and for the record not all 2 strokes have the pins but these are usually the little crappy ones.  I have had a couple of... umm errors in judgement that have required disassembling the engines again shortly after running and trust me the rings move while the engine is running, most engines we strip down have at least one cylinder with all the rings lined up.  There was one job that sticks in my mind rather well, one of our trucks which ran great and never burned any oil had an oil pump failure and spun a big end bearing, when we disassembled the engine the rings on all but one piston were lined up, if it didn't affect an engine that runs 22:1 compression it won't worry one that only has 9:1, so basically the ring gaps don't matter a sh!t where they are because they will move anyway.

If you have first-hand experience on that, I will stick to that because I was just thinking out loud!

[Trevor from Warragul]

a lot of 2 strokes have a pin in the ring gap because they rely on having compression on both sides of the pistons to run

Sorry, that's not the reason!  If they didn't have pins the rings will rotate, snag the transfer ports & snap.

[70CB750]

I believe it is good for the rings to rotate, they are supposed to be sort of floating seal if you know what I mean.
But this thread is an excellent example why I read SOHC as much as I can. Always learning new things

[trueblue]

a lot of 2 strokes have a pin in the ring gap because they rely on having compression on both sides of the pistons to run

Sorry, that's not the reason!  If they didn't have pins the rings will rotate, snag the transfer ports & snap.

Can I claim a brain fart on that comment, but not all 2 strokes have the pins, I have seen a few on small crappy engines that don't have them.  Also I'm not saying to line up the ring gaps, I'm saying that if you did it wouldn't matter, I still stager the rings when I assemble but I have poked a couple of pistons in engines and forgotten to check where they were lying, didn't think of it till the engine was already running, after running it in checked the compressions and they were within a couple of psi, so it obviously didn't matter.

[lucky]

First of all, I am that idiot.

Just finished putting rings on my '73 cb500 (no. 4 rings were stuck good and tight). Followed the manual to the letter (almost, ugh) and now have it 99% back together. Carbs on, just need to hook all the cables back up. Woke up in the middle of the night with the dread that I can't remember staggering the rings. I want to say I did, but damn it I can't remember. I haven't started it back up yet, so......what do I do?

Stop now and tear it all back down to confirm or proceed on forward and check compression after its broken back in to see where they stand?   And then need another set of rings...

Side question, my thought was that a compression test on freshly honed cylinders and new rings wouldn't tell me much at this point.  Am I correct?

And to sum up, I am an idiot...

Think of it another way...
Do you remember taking the time to LINE UP all of the piston ring gaps???

No you did not.

Natural for beginners to worry.

[MCRider]

The rings start moving around as soon as the pistons start moving in the cylinders, so I wouldn't worry about it.  And, no, a compression test on freshly-honed cylinders with new rings won't tell you much, other than the fact that you have less than perfect compression, which is to be expected with new rings and a hone. 

Yeah what he said ^^^^^^^^^

Yes these guys are right. This was covered in a thread some time ago. I did a lot of Googling on the subject and found some actual tests where someone made a special engine with observation ports and all kinds of elaborate ways of analysing ring rotation.

Different rings rotate at different speeds than other rings and at diffferent rpms as each has their own special points of harmonic resonance, etc etc.

Bottom line was the rings rotate considerably on their own and the idea of spacing them at install is meaningless. Do it if it makes you feel better. Don't worry about it if you don't.

[Lil Red]

I always thought that ring staggering was a myth...one of those things passed down by generations from the flathead side valve era...but did it anyway...I dont know from experiance, i've never looked inside a running motor...but have heard tell as above, that they do move around quite a bit...but anyway...yeah...I dont think you have to worry about it...I suppose it's like the lottery...some pick their own numbers, others let the computer pick the numbers...both still win occasionally...that sort of thing...On my Guzzi once in the 20 years of owning it...I did fire it up and it was like I was spraying for mosquitoes for about 3 minutes...scared me senseless....then it stopped and NEVER happened again...I attributed it to rings just lining up just so...who knows...good luck with it.

[trueblue]

One thing to think of, if the rings don't rotate you will get a gap in the wear pattern in the cylinder at the top of the cylinder where only the top ring reaches and the same at the bottom where only the bottom ring reaches.

[MCRider]

as SO:
http://www.sacskyranch.com/piston_ring_rotation.htm

From Wicki:
"It is considered good practice to build a new engine with the ring gaps staggered around the circumference of the bore. This means that any escaping gas must negotiate a labyrinth before escaping past the rings. However, while the engine is running, the rings will tend to rotate around the piston and not remain in the position as fitted. Many rings will then stick in one spot at random and remain there for the life of the engine. For this reason, ring position during build cannot be considered to be important although most engine builders would feel uncomfortable assembling an engine with the gaps aligned."

I know many people poo poo wickipedia, but on balance If find it to be very helpful. Common sense goes a long way to weeding out the slop.

[Rigid]

If the location of the rings were that critical they would be pinned so they can't turn, a lot of 2 strokes have a pin in the ring gap because they rely on having compression on both sides of the pistons to run.

I always thought the rings were pinned to keep them from rotating around with the end sliding into a port and damaging them?  Anyway, ring end gaps will align and you will lose all compression on that cylinder momentarily.  Happens all the time and is one reason for intermittent rough running complaints.  Very noticeable in a 4 cylinder, 320 cubic inch aircraft engine.

[754]

 Not all 2 stokes have transfer ports , I think, so reedvalve or rotary valve engine may run without pins.

 here is what I do with rings ;
 Top ring 180 degrees AWAY from point between plug and exh valve, tho other 120 degrees from that..

 The motors ran great, little things CAN make a difference.

...
Ring spinning Theory;

 If it true..your compression will get higher soon if you put them in straight.
...
Would I tear it apart ..probably not..

[lrutt]

If the location of the rings were that critical they would be pinned so they can't turn, a lot of 2 strokes have a pin in the ring gap because they rely on having compression on both sides of the pistons to run.

They pin 2 strokes so the ring ends don't rotate to a position to get hung up in an intake, exhaust, or transfer port. That is the only reason. The crankcase compression you speak of is an order of magnitude less than that above the piston so a non-issue.