GS1000G pistons too big! GS1070G

[Anonymous]

Hi all I`m a newbie and this site has been very helpful in the restoration of my old 1980 GS1000GT.
Well having purchased the machine about 2 years ago its been running fine other than the normal oil leaks from between the cylinder head and block on the outside studs(oil ways). So I decided to strip it down and replace both the head and base gaskets etc to cure the problem. Now the old girl has about 45000kms on the clock so I though lets check the rings and the barrels for wear. All looks good still have some of the hoaning marks on the boars with hardly any scuffs on the pistons. Great I thought buy a set of new rings and put it back together, right? wrong! I cleaned the crown of the pistons and looked for any oversize stamps, none that I could see. Then just to make sure I measured the dia of the pistons as described in the workshop manual. 72.5mm!? now I do the math and come up with 1070cc the block is stamped 997cc and the engine number starts GS100G-xxxx.

Here is the question. Has anyone come across this before? I don`t think they are GS1100G pistons as these are still too big, I think. But they are definately 2 vavle pistons. Also the head gasket is now all metal instead of part material with metal at the cylinder openings, is there anything different in installing this head gasket?
Hope someone can help.

[Anonymous]

oversize

What size are the wrist pins? 18mm?also did you order the head gasket for a stock 1000 and are the cylinder holes the proper size for the bore?

[Anonymous]

Hi Gee-s-is
My digital calipers had a flat battery.
Dumb me! The pistons look like they are 1mm over size (SN100 on second ring) GS1100G pistons (72.95mm) after all. The wrist pins are 18mm as you suggested

But the head gasket is causing me a bit of concern (11141-49410), it is aparently suzuki`s replacement for the standard original head gasket.
It came in the complete gasket kit (11402-49833).

[Guy]

72.5mm seems a strange size. Standard pistons are 70mm, wiseco do two piston kits: 73mm (1085cc) and 73.5mm (1100cc).

[Anonymous]

The size is 72.95mm 2 valve piston the 2nd ring has "N 100" stamped on the upper surface denoting i believe 1mm oversize rings. So I think the pistons are 1mm oversize GS1100G pistons, as these pistons standard size are 71.949 - 71.96mm. Still I`ll be going down to my local dealer on Monday with piston in hand, and to ask them about this new style head gasket!
Thanks anyway Guys.

[focus frenzy]

I have a stock 1000G piston right here and the only markings are a arrow on the crown showing what way it is suspose to be put on the rod, (pointing foward) it has suzuki, made in japan cast on the inside of the skirt with a 4^ next to it and a L and what apears to be the mold numbers on the other side, inside the skirt.
I am running 1MM over sized pistons (71MM) and if memory serves me correct, they had 1.0 cast on top of the dome between the valve clearance cut outs.

also there is the letters ART on the right side next to the hole for the wrist pin.

[Anonymous]

Yeah, I have no suzuki markings I can see, just the arrow and a "C" just below that on the crown on the piston, underneath a casting number on the boss of the wrist pin hole (L/H) and a W inside an oval on the otherside (R/H).
Ah ha, wiseco pistons??? I love it when things are a mistery, I`ve now entered the twilight zone.