GS1100G pistons

[gu3]

Hi all,

Needing to rebuild by 83 GS1100G and needing some info on pistons. There is only one company producing pistons specifically for the GS1100G (Dynoman). I've seen online that GS1000 pistons work in the GS1100G, just need to get the right diameter. both the GS1100G specific and the GS1000 pistons are 10.25:1 compression which is greater than the factory 8.8:1. My question is:

1. Will the GS1000 pistons just fit in without having to machine anything (assuming bores are sized correctly)
2. Will the increase in compression ratio mean that the pistons will now hit the valves?

Thanks

[Nessism]

Cruzin Image makes a piston kit.

https://www.cruzinimage.net/2017/08/25/78-81-suzuki-gs1000-1100cc-bigbore-piston-kits-with-head-gasket/

[Chuck78]

One thing to consider is that the 1100 stroke is longer, so when reading the compression ratio on a pair of GS1000 pistons for use on a GS 1100, the compression when used on the 1100 will be higher I believe, as you have the added stroke change figured in. There is also a difference in deck height I believe, but I would imagine the piston compression height is going to be the same. So a Wiseco GS1000 big bore piston kit would be higher than advertised compression ratio when used on the longer stroke, and therefore you may want to see out 1100-specific pistons.
Running 1100 pistons on a 1000 will yield you higher than stock compression, but you may need to check piston to valve clearances, although the deck height needs to be adjusted when using the 1100 cylinders, as well as a thinner base gasket used, or possibly just using case sealer instead of a base gasket although that might be a recipe for never getting the cylinder off the crank case ever again!