Piston Rings GT380

TLRam1 · Post by **TLRam1** » Sat Dec 13, 2008 9:23 pm

I have new Suzuki pistons and rings. The rings came together and undisturbed, had to work a little to separate.

The issue I wonder if others have had is a few of the rings are too wide to fit in the groove. The rings stay stuck unable to compress in. I thought it was the pistons at first but the rings that work do so in all of the pistons, the others do not.

rngdng · Post by **rngdng** » Sun Dec 14, 2008 2:20 am

I hope you realize that Suzuki used "Keystone" rings. On some pistons, only one of the rings is a keystone. The keystones are not square, but are triangular-shaped, and if put in a square piston groove, they will stick.

Lane

Suzukidave · Post by **Suzukidave** » Sun Dec 14, 2008 5:04 am

rngdng wrote:I hope you realize that Suzuki used "Keystone" rings. On some pistons, only one of the rings is a keystone. The keystones are not square, but are triangular-shaped, and if put in a square piston groove, they will stick.

Lane

http://kawtriple.com/tripleed/dalegt380/sm20.jpg

Coyote · Post by **Coyote** » Sun Dec 14, 2008 8:10 am

I'm betting thats your problem. Both rings on the 550 are keystone type and only the top ring on the 380.
When I rebuilt my 550 last year, NONE of the rings were lettered or marked in any way. I had to use high magnification and a true straight edge to determine the beveled side. A jewelers loupe works good.

GT Tim · Post by **GT Tim** » Sun Dec 14, 2008 10:02 am

Terry,
I'm sorry about the mix-up with your rings. I didn't know that the 380 took two differnt rings per piston, why would anyone expect that who hadn't been inside one to find out or been Suzuki schooled.

My part software doesn't make the distinction either.

Since I sold them to you and, although I don't know what I could have done better for you to avoid this problem with the knowledge and tools I have, if you want me to make it up to you let me know what you would like.

Tim

TLRam1 · Post by **TLRam1** » Sun Dec 14, 2008 11:42 am

I knew they were Keystone but thought they were All Keystone. Maybe I am trying to put a square one in a keystone angled groove if they are angled.

The bottom ring is okay in the photo, just the top ring is the issue

Let me work with this some more.

TLRam1 · Post by **TLRam1** » Sun Dec 14, 2008 9:36 pm

What I have found....not much.

1. The pistons seem to have square grooves.

2. I don't have an accurate enough mic for a good measurement.

3. The 3 rings will not work in the top or bottom groove, markings are facing up.

4. Tried the 3 rings in my old pistons, same result.

5. My old pistons seem to have square grooves also.

This is a 75 GT380, could they be different than other models? I am not sure where to go from here.

Nope Tim, this is something you wouldn't know, no problem, I am not sure what direction to go yet.

I will look up part numbers on the boxes and see what they go to.

These are .50 OS

Piston - 12110-33701

Rings - 12140-33700 the last 0 was changed to 1, probably the same but a number update.

GT Tim · Post by **GT Tim** » Sun Dec 14, 2008 9:41 pm

Part # = 12140-33701
Part Description = RING SET,PISTON
Model Count = 13
GT250-B 1977 247 GT250 HUSTLER STREET
GT250A 1976 247 GT250 HUSTLER STREET
GT250K 1973 247 GT250 HUSTLER STREET
GT250L 1974 247 GT250 HUSTLER STREET
GT250M 1975 247 GT250 HUSTLER STREET
GT380-B 1977 371 GT380 SEBRING STREET
GT380A 1976 371 GT380 SEBRING STREET
GT380J 1972 371 GT380 SEBRING STREET
GT380K 1973 371 GT380 SEBRING STREET
GT380L 1974 371 GT380 SEBRING STREET
GT380M 1975 371 GT380 SEBRING STREET
T250-2 1970 247 T250 HUSTLER STREET
T250R 1971 247 T250 HUSTLER STREET

GT Tim · Post by **GT Tim** » Sun Dec 14, 2008 9:43 pm

Part # = 12110-33701
Part Description = PISTON
Model Count = 6
GT250L 1974 247 GT250 HUSTLER STREET
GT250M 1975 247 GT250 HUSTLER STREET
GT380J 1972 371 GT380 SEBRING STREET
GT380K 1973 371 GT380 SEBRING STREET
GT380L 1974 371 GT380 SEBRING STREET
GT380M 1975 371 GT380 SEBRING STREET

TLRam1 · Post by **TLRam1** » Sun Dec 14, 2008 9:57 pm

Tim, what pulls up for the ring number with a zero at the end as the zero was changed with a pen? I sent Craig380 a PM to see if he can shed some light on this.

I don't know who else to PM for info.

TLRam1 · Post by **TLRam1** » Sun Dec 14, 2008 10:00 pm

Is there any info or closeup photos I can take that would help someone give a answer?

GT Tim · Post by **GT Tim** » Sun Dec 14, 2008 10:05 pm

Part # = 12140-33700
Part Description = RING SET,PISTON
Model Count = 1
GT380J 1972 371 GT380 SEBRING STREET

Craig380 · Post by **Craig380** » Mon Dec 15, 2008 3:32 am

I've re-ringed my '76 380 twice -- in 1999 when replacing a failing rod end bearing, and again in 2007 when I rebuilt the top end with a good used set of pistons and cylinders.

Both times, I had no problems with ANY of the rings sticking in the piston grooves. All rings & pistons were genuine Suzuki. And ALL the rings I got were of the keystone type, with a tiny letter indicating the top surface of the ring.

Now, the caveat here is, I was fitting new rings to used pistons. Maybe the ring grooves in the pistons were a little worn ... I don't know.

I was super-paranoid about putting the rings in the wrong way up, and ALL rings had angled top faces, I checked this.

Now, I must admit I always thought both top & bottom rings on each piston were of the keystone type.

All I can tell you is the bike has run great with (apparently) mixed rings for 10,000+ miles.

One thing is did notice -- the ring 'cutouts' that fit the locating pin in your photos look a LOT shallower than the cutouts on the rings I have. I will have to check when I get home.

Craig380 · Post by **Craig380** » Mon Dec 15, 2008 3:41 am

Actually, another thought -- are you sure the rings you have are 0.5mm oversize?

I was lucky when I rebuilt mine last year, I'd got a collection of 0.5 oversize rings which were ideal for the piston / cylinder set I got.

Suzi did make oversize rings to suit the oversize pistons and they had different part numbers -- I'll have to check my parts book for the numbers.

GT Tim · Post by **GT Tim** » Mon Dec 15, 2008 4:54 am

Craig380 wrote:Actually, another thought -- are you sure the rings you have are 0.5mm oversize?

I was lucky when I rebuilt mine last year, I'd got a collection of 0.5 oversize rings which were ideal for the piston / cylinder set I got.

Suzi did make oversize rings to suit the oversize pistons and they had different part numbers -- I'll have to check my parts book for the numbers.

Yes they are...at least marked as such.
http://www.alpha-sports.com/clas/1972%20GT380/34.htm
http://www.alpha-sports.com/clas/1977%20GT380/37.htm

Only thing that could be, -33700 shows '72 only, -33701 is '73 to '77 superceeded number for all years.

Unless there is something peculiar about -33700 that doesn't interchange with '73 to '77, and the person at the shop I bought the inventory from was incorrect when they changed the part number on the box assuming 2 way interchageability.

But does anyone have a set of -33701 to compare?

Tell me....

Do the rings work in some pistons and not others?

Do they work in all pistons, but in only the top groove or bottom groove?

Or do you get two of the rings I sold you in one piston, and none fit in the next?

Does the ring fit in the top groove in one piston, and in the bottom groove of the next?