Piston ring positions - How critical???

[juicydangershow]

Hi everyone! I wanted to say thanks to the great resource this site is and everyone who posts, its been a ton of help getting through my bike. This is my first post!

I am a new owner of a 1981 GS850G that was apparently prettied up for a premium sale... and that lucky buyer was me! This is my 3rd bike and the first I have ever done any real work on ( previous bikes - 1988 Yamaha Radian 600 and 1991 Honda Nighthawk 750). Since I was always fortunate to have good sellers with past bikes, I never had to. I am mechanically inclined and know a decent amount about engines, etc. but I am no gearhead by any means. I hope to post a bunch about what I have done and some pics too at a later time.

I disassembled the whole top-end down to the base gasket. I cleaned everything, scraped gaskets (base gasket is a nightmare!!) and reassembled everything with gaskets from Vesrah. I used their "complete" kit, which still doesn't come with a few pieces I thought should be there... cam tensioner and starter cover gaskets I hand cut from gasket sheets (easier than I thought, but would have been nice to included those in a "complete set"). Also the head gasket washers were confusing and should be built into the head gasket or come with instructions. Took several hours of hunting on the GS forums to figure out where they go (installed on top of the head gasket over the corner four corner stud oil passages - I hope thats where they go!!). I sure hope they stayed in place when I seated the head as well.

Anyway... on to my questions.

When reinstalling the pistons I was following the shop manual which stated the TOP and 2ND ring are spaced at about 10 o'clock and 2 o'clock if looking at the piston from the top and the intake side is at 12 o'clock. SOMEHOW my dummy self was futzing away getting them all set and trying to slip the pistons into the cylinder sleeves and positioned them all REVERSE. So now my TOP and 2ND rings are all around 8 o'clock and 4 o'clock. (See image for positions).

How crucial is this going to effect the bike? I already buttoned up everything with the head now installed and torqued down. Cams are installed and cam guides are all torqued. I am just waiting on some shims to finish this part of the engine and put the valve cover on. It wasn't until after all that I was mentally running through all the assemblies that this issue popped in my head!

Any thoughts??

Again, thanks for the great resource site and I hope to post a bunch of things in return.

Special thanks the BikeCliff's website tutorials (shop manual PDF was a life saver too!!), the Carb Cleanup series on the GS Resources, Rob at Z1, and the o-ring guy at cycleorings.com (get all your o-rings there and stainless intake boot fasteners!) and all the posts I have read.

 

[Dave8338]

mmmmmmmmmmmmmmmmmmmmmmm... you may run the risk of blow-by, but without running the thing, I'm not sure. If it were me, (and I hate to say this) but I'd have to tear it apart and do it right.

 

[rustybronco]

Anyway... on to my questions.

When reinstalling the pistons I was following the shop manual which stated the TOP and 2ND ring are spaced at about 10 o'clock and 2 o'clock if looking at the piston from the top and the intake side is at 12 o'clock. SOMEHOW my dummy self was futzing away getting them all set and trying to slip the pistons into the cylinder sleeves and positioned them all REVERSE. So now my TOP and 2ND rings are all around 8 o'clock and 4 o'clock. (See image for positions).

How crucial is this going to effect the bike? I already buttoned up everything with the head now installed and torqued down. Cams are installed and cam guides are all torqued. I am just waiting on some shims to finish this part of the engine and put the valve cover on. It wasn't until after all that I was mentally running through all the assemblies that this issue popped in my head!

Any thoughts??

Personally I wouldn't worry about it. leave it as is.

***EDIT*** it might use a little more oil.

 

[hampshirehog]

The rings move around anyway - that's why strokers have pegs to stop the ends poking in to the ports. I don't know why the Jap manuals specify the ring positions - every other manufacturer just seems to specify spacing the gaps at 120 degrees apart.

Don't worry about it - as long as the gaps don't align you won't get blow-by.

 

[dardoonk]

The rings move around anyway - that's why strokers have pegs to stop the ends poking in to the ports. I don't know why the Jap manuals specify the ring positions - every other manufacturer just seems to specify spacing the gaps at 120 degrees apart.

Don't worry about it - as long as the gaps don't align you won't get blow-by.

That is my understanding as well. They're going to move, so the most important thing is to keep them spaced apart.

I wouldn't go back and change what you've done.

 

[TheCafeKid]

Some of the manuals for different bikes specify, and it seems some only say 120 degrees. You basicly have done just the opposite arrangement of the manual, so I agree, I wouldnt worry about it. Should be just fine, as all you are preventing is them lining up.

 

[juicydangershow]

Thats what I thought as well... setting them 120 degrees apart, but since the shop manual has them 90 degrees apart, I set them that way (although on the wrong side). I hope they don't move too much - or at least not moving the gaps toward one another.

My perfectionist self WOULD go back and do it right, but tearing it all down again - plus if the head or base gasket get ruined while doing so - ugh, that would keep me off the road and not able to do the other fixin's I have planned for the bike.

I've only had the bike 2 months. One month of rough riding, oil weeping/dripping, and overall in need of a lot of TLC. The other month its been torn apart at a friend's garage. My riding season up here is drifting away!!

I'll probably just leave them and see how it runs. If I have to tear it down later, so be it.

 

[Agemax]

rings should b fitted as stated by the manufacturer. they do this for a reason for optimum performance and ring longevity. rings do not generally turn during use if fitted correctly and the reason they fit pins on 2 stroke piston ring grooves is to make sure you fit them in the right place, so as to avoid the ports in the cylinder.
sorry mate but if that was me i would strip and rebuild correctly as i wouldnt be able to sleep properly!

 

[juicydangershow]

Well I am on the edge of not sleeping over this! And I could probably get down to the taking the cylinders back off pretty quick and back together in a half day... but the gaskets are what really holding me back (and that I am soooooo close to having this thing sealed up and can work on the other things needed).

Would you think I could reuse the gaskets after torquing the head down? I would hate do tear it down to correct this and have leaking gaskets... I also wouldn't want to wait for more gaskets or pay $$$ from the local dealer here for them.

 

[TheCafeKid]

Well I am on the edge of not sleeping over this! And I could probably get down to the taking the cylinders back off pretty quick and back together in a half day... but the gaskets are what really holding me back (and that I am soooooo close to having this thing sealed up and can work on the other things needed).

Would you think I could reuse the gaskets after torquing the head down? I would hate do tear it down to correct this and have leaking gaskets... I also wouldn't want to wait for more gaskets or pay $$$ from the local dealer here for them.

As long as no real heat has been put to them, you should be fine. We had to pull a fellow GSRs head back off after torquing it down, and for chits and giggles, we tried reusing the head gasket and it was fine. I have used gaskets elsewhere a couple times, as long as they came off cleanly. Should be ok, especially since as I said, youve put no heat to it if any at all.

 

[Agemax]

as cafe kid says, with minimal use the gaskets should be ok to use again

 

[Guest]

not that i'm an expert...

not that i'm an expert...

if your head gasket has crushable parts then when you torque it down those bits are going to, well, crush
when re-using the gasket you wont get the exact same seal but the gasket may not necessarily leak
if your gasket is the "rubberised metal" type, i think you should definitely be ok reusing it

if you dont put the rings the way the service manual calls for, if you encounter any probs (low compression, using oil, smoking, etc) you'll never be able to be sure if that might be due to the ring position
if you put them correctly, you can readily eliminate the ring position as a cause of possible probs
to my knowledge the rings do not move from their original position (and thats achieved as a part of the rings' "bedding in" proces)

if the reason for a specific gap position was only to counteract the possibility of them lining up, i think you would want them 180deg apart, which isnt the case

 

[tkent02]

Run it, break it in, test the compression.
If it's compression is low and it is running poorly, rebuild it over the winter.
It will be fine.

There was a guy who lined up all the gaps together perfectly at one of the European car engine factories, Porsche I believe. Thought he was doing it right. A lot of engines were put together that way. Most ran fine and very few were ever returned.
There GS engines are known to be pretty reliable. You really think the little Japanese kids that put these rings in thirty years ago did them all exactly right?

Easy enough to fix later if you need to.

A wasted riding season is not replaceable.

 

[juicydangershow]

I'll have to sleep on this (or not). At first I thought I would just leave them, but as I am thinking... the engine is tilted forward toward the exhaust slightly. If the rings are positioned on the intake side, the gaps may vibrate away from each other and seat themselves closer to 120 or 180 degrees apart during initial break-in after reassembly. BUT... the part that worries me is, where they are now and the gaps rotate toward one another (due to the angle of the engine).

What a dilemma.

 

[Dave8338]

I'll have to sleep on this (or not). At first I thought I would just leave them, but as I am thinking... the engine is tilted forward toward the exhaust slightly. If the rings are positioned on the intake side, the gaps may vibrate away from each other and seat themselves closer to 120 or 180 degrees apart during initial break-in after reassembly. BUT... the part that worries me is, where they are now and the gaps rotate toward one another (due to the angle of the engine).

What a dilemma.

I was just thinking of this exact same scenairo...and let me add a little more "what if". IF they do move the likely possibility of the gap landing IN the exhaust port is, at the very least, possible. Now, add to that the exhaust temps on an "open" end of the ring (where there is less material to dissipate the heat) and "is there a chance of melting the end of a ring"?
....more food for thought..... :-k

 

[hampshirehog]

The rings will move, though they won't spin 'round and round'. May be up to 15 degrees or so and then they'll stay put as they bed in. I used to be real finicky about this years ago but once I realised they shifted only put them in roughly and it makes no difference. (Except when using old rings as they will have bedded in where they were when you split the motor, but even then you'll never line them up perfectly)

The reason for the 120 degree split is for the oil ring. Yeah, I know it's not there for compression but it can't do any harm can it.

 

[tkent02]

IF they do move the likely possibility of the gap landing IN the exhaust port is, at the very least, possible.

I'm sorry, this is a four stroke, the ports are in the head.

 

[TheCafeKid]

I was just thinking of this exact same scenairo...and let me add a little more "what if". IF they do move the likely possibility of the gap landing IN the exhaust port is, at the very least, possible. Now, add to that the exhaust temps on an "open" end of the ring (where there is less material to dissipate the heat) and "is there a chance of melting the end of a ring"?
....more food for thought..... :-k

The rings, from what i can tell, never see beyond the jug, so its not possible for them to end up over the ehaust port.

180 degrees would be ideal if there were only TWO rings, since there are 3, its 120. My logic says the rings themselves have no idea where they are in relation to the cylinder. The cylinder is symetrical in all directions, so as long as they are 120 degrees apart they dont care, nor does the motor care where they are lined up.

 

[bwringer]

Oh, fer Pete's sake...

Go ride the snot out of the thing and don't trouble yourself one more moment about this.

As long as the ring gaps are not lined up, you're fine. It won't make the slightest difference to compression or oil consumption. The important part is that the gaps are staggered, not precisely where they point.




Oh, by the way, I've successfully rebuilt four GS850 engines and top ends, along with lots of other bikes and cars.

 

[TheCafeKid]

Oh, fer Pete's sake...

Go ride the snot out of the thing and don't trouble yourself one more moment about this.

As long as the ring gaps are not lined up, you're fine. It won't make the slightest difference to compression or oil consumption. The important part is that the gaps are staggered, not precisely where they point.




Oh, by the way, I've successfully rebuilt four GS850 engines and top ends, along with lots of other bikes and cars.

Thank you! Words of wisdom, words of wisdom. There is no magic behind where the rings point. Some guy at Suzuki, Clymer or Haynes layed out the diagram, and it just so happens thats where he pointed them in it. At least thats the way i look at most of this stuff. Judging by the design of everything else, were they supposed to be pointed in a specific direction, there would be marks on the jugs, the way they mark alignment of everything else that requires it on the motor