GS1100G Largest Bore On Stock Cylinders

[BretIPC]

I have been looking for parts for an engine build on. 1982 GS1100G.  There are a lot of piston options out there in both size and compression.  I am trying to figure out how big can we go on the stock cylinder/sleeve before needing to resleeve.  I'm not saying I am going to just hog it out to the max, I just want to know what my limits are so I can weigh the costs of different options.

 

Thank you.

[gs7_11]

I'm surprised there are a lot of options out there, assuming your bike is the 8 valve shafty (g model).

Are you sure you're not looking at 16 valve pistons?

[BretIPC]

1 minute ago, gs7_11 said:

I'm surprised there are a lot of options out there, assuming your bike is the 8 valve shafty (g model).

Are you sure you're not looking at 16 valve pistons?

I am not sure if I was looking at the correct pistons.  I just started doing some research and most pistons come up as just GS11000, they don't specify which sub-model.  I didn't get as far as measuring the pistons or wrist pins or anything yet.  I just started looking around at things.  I know the stock size is 72mm, and most of the pistons I see are 74mm and up.

[Duckndive]

you can go to 75mm "3mm over" but liners will be thin near the bottom 

but for a road bike 74mm is the norm 

[Mike711]

Remember, what the septics call a GS1100 is a GSX1100 over here

[Gixer1460]

1 hour ago, Mike711 said:

Remember, what the septics call a GS1100 is a GSX1100 over here

Which is doubly confusing as the Euro / UK GSX1100G was oil cooled 16v! but the GS1000G - 8v wasn't LOL!

[BretIPC]

Does anyone know of a good source for pistons for a 2-valve?  Alternatively, can a 4-valve head be swapped out?

[Duckndive]

22 minutes ago, BretIPC said:

Does anyone know of a good source for pistons for a 2-valve?  Alternatively, can a 4-valve head be swapped out?

If your in the USA there are plenty 

MTC , Orient Express to name a couple  

[BretIPC]

1 minute ago, Duckndive said:

If your in the USA there are plenty 

MTC , Orient Express to name a couple  

I'll have to give MTC a call.  At first glance, it all seems to be for 4-valve

[BretIPC]

2 hours ago, BretIPC said:

I'll have to give MTC a call.  At first glance, it all seems to be for 4-valve

I called MTC and they don't make anything for the 2-valve.  I also called Webcams about camshafts and they don't make anything.  Both of them said they were not aware that a 2-valve GS1100 even existed.

[Duckndive]

1 hour ago, BretIPC said:

I called MTC and they don't make anything for the 2-valve.  I also called Webcams about camshafts and they don't make anything.  Both of them said they were not aware that a 2-valve GS1100 even existed.

Is yours a 2V or 4V  ? 

[BretIPC]

1 minute ago, Duckndive said:

Is yours a 2V or 4V  ? 

2-Valve

[Duckndive]

1 hour ago, BretIPC said:

2-Valve

https://www.orientexpress.com/p-1236-wiseco-piston-suzuki.aspx

https://www.wiseco.com/product-category/powersports/?wpce_search=147911

Edited January 22 by Duckndive

[BretIPC]

19 minutes ago, Duckndive said:

https://www.orientexpress.com/p-1236-wiseco-piston-suzuki.aspx

https://www.wiseco.com/product-category/powersports/?wpce_search=147911

The product you linked to was for a 1000.  Will those pistons fit in an 1100? 

I'm going to head to the garage soon and take a bunch of measurements so I can check and compare things.

[Duckndive]

1 hour ago, BretIPC said:

The product you linked to was for a 1000.  Will those pistons fit in an 1100? 

I'm going to head to the garage soon and take a bunch of measurements so I can check and compare things.

Ignore that if you have  2V  read the piston sizes and cc 

[BretIPC]

10 minutes ago, Duckndive said:

Ignore that if you have  2V  read the piston sizes and cc 

Got it

[kochic]

if you scroll down you will see a kit for the Gs1100G/GK .

Marc

http://www.dynoman.net/engine/pistons/custom.html#suzuki

[BretIPC]

14 hours ago, kochic said:

if you scroll down you will see a kit for the Gs1100G/GK .

Marc

http://www.dynoman.net/engine/pistons/custom.html#suzuki

Thank you. I reached out to them  4-6 weeks out to get, but available.

Does anyone know of a source for valves?  I already talked to Web about a cam.  I would have to have it welded and custom ground, but again it can be done.  I'm sure I could get custom valves made somewhere, but wondering if there is a source for them currently.

[BretIPC]

I'm in talks with APE now.  They seem to have knowledge and experience with these engines and can supply some of the parts.  Still going back and forth with them to see what all the available options are.

[BretIPC]

APE doesn't sell the OS cylinder kits for this.  They mostly deal with just the 16-valve stuff.  I am assuming I can still re-sleeve this one if I want to go bigger.  Can anyone confirm that there are sleeves for this that would achieve this?  Are the 16-valve engine sleeves compatible with the 8-valve cylinders?  I know the p/n of the cylinder assembly is different.

Also, does anyone know about options for valves and valvetrainparts? Kibblewhite seems to have everything listed under GS1000 except for the valves.  They said I could probably use KZ1000J valves, but they weren't 100% sure. 

I see APE makes valves for the 8-valve, but they are quite a bit oversized.  Is there anything to gain with larger valves with only slightly larger pistons?  If not, at what displacement should the valves be oversized?

As a disclaimer, this is not my engine.  I have a motorcycle shop.  I mostly work on dirtbikes and ATVs from within the last 20 years or so.  I also specialize in cylinder head machining.  I don't turn away from much, but I am not familiar with these older street bikes.  The customer brought me the engine and wants to build it to the street/strip bike.  I think it was assumed that with the availability of parts listed as GS1100, this would be a simple process with lots of options.  Thanks to the help of this forum and also conversations with suppliers I am narrowing it down, but it still isn't simple.

[gs7_11]

It's a lot of effort and trouble to do this on this bike, and being a shafty, maybe not the best starting point?

Perhaps the lack of available tuning parts is a clue?

Anything's possible of course. 

[Gixer1460]

I think this ^^^ is the real issue, that and your inexperience with the subject in hand. I don't doubt your mechanical skills but a 4 banger isn't just a single x4, they can be waaaaay more complicated and you are trying to modify it as well without the background knowledge of what's out there or what works with what. As said very few shafties get modified into 'go faster bikes' - that isn't their reason for existence! I'd start searching for OEM overbore pistons +0.25 and + 0.50mm - they won't be common or easy to find but you never know, they'll be an easy machining job and they are designed to work with extg. stuff. Valves - why change? are they burnt up or cracked? Maybe they are ok and its the guides that are worn? Maybe the seats are damaged? Any decent shop that does head work (especially on bike heads) will be able to source parts - valves, seats, guides and seals easier and quicker than you, stumbling through the swamp that is the internet of vague & incorrect & conflicting information. May be not much help but fixing 40yr old motorcycles with minimal spares is REALLY hard these days!

[BretIPC]

3 hours ago, Gixer1460 said:

I think this ^^^ is the real issue, that and your inexperience with the subject in hand. I don't doubt your mechanical skills but a 4 banger isn't just a single x4, they can be waaaaay more complicated and you are trying to modify it as well without the background knowledge of what's out there or what works with what. As said very few shafties get modified into 'go faster bikes' - that isn't their reason for existence! I'd start searching for OEM overbore pistons +0.25 and + 0.50mm - they won't be common or easy to find but you never know, they'll be an easy machining job and they are designed to work with extg. stuff. Valves - why change? are they burnt up or cracked? Maybe they are ok and its the guides that are worn? Maybe the seats are damaged? Any decent shop that does head work (especially on bike heads) will be able to source parts - valves, seats, guides and seals easier and quicker than you, stumbling through the swamp that is the internet of vague & incorrect & conflicting information. May be not much help but fixing 40yr old motorcycles with minimal spares is REALLY hard these days!

Isn't the whole purpose of these forums to share information and help people who may not have as much knowledge as others?

I've been building engines my whole life.  Everything from single-cylinder bikes to modern sportbikes to V-8s to diesel truck engines.  A few months ago, I built a 900cc 3-cyl Can-Am engine that with the right turbo will hold up and put out 450hp (I only built the long block and I don't think he has enough turbo to make that, but it was too much for the stock engine).  I have a full cylinder head machine shop and am direct with a lot of big-name manufacturers.  To me, an engine is an engine.  They all operate on the same principles.  Yes, I don't have experience with these old Suzukis, that's why I came here.  If it was a 16-valve engine I could go to any of my suppliers and just pick parts directly out of their catalogs and be fine.  This one ended up being an oddball and there weren't direct parts listings.  Even MTC and Webcams told me that they never heard of an 8-valve GS1100 and they are big names in this industry.  I didn't want to just order a bunch of parts, hoping I could make them work then have to deal with returning them, or even worse not be able to return them because the were special ordered or made.

I have pretty much figured it all out at this point between the information I learned on here and from talking to Kibblewhite, Webcams, and APE.  I took the options that I found available and talked to the owner and decided the route to go.  Just have to locate a few small things still to finalize the parts list.

Thank you all for your input!

[Gixer1460]

I wasn't having a dig! The problem is you are there and we (for the most part) are here and we, for obvious reasons have to order stuff from the States so its just as difficult for us as you being in the 'land of speed shops' !

Here is a link to a source of stuff in Europe - piston page example . . . . most listings aren't available - these are but no idea on sizes! ! ! - https://www.cmsnl.com/suzuki-gs1100g-1982-z-usa-e03_model15998/partslist/BLCK0011.html Prices seem almost double the out of stock items + postage will be steep from Europe but its a crap shoot if you can't find them Stateside!

[wraith]

On 1/26/2024 at 10:15 AM, Gixer1460 said:

I think this ^^^ is the real issue, that and your inexperience with the subject in hand. I don't doubt your mechanical skills but a 4 banger isn't just a single x4, they can be waaaaay more complicated and you are trying to modify it as well without the background knowledge of what's out there or what works with what. As said very few shafties get modified into 'go faster bikes' - that isn't their reason for existence! I'd start searching for OEM overbore pistons +0.25 and + 0.50mm - they won't be common or easy to find but you never know, they'll be an easy machining job and they are designed to work with extg. stuff. Valves - why change? are they burnt up or cracked? Maybe they are ok and its the guides that are worn? Maybe the seats are damaged? Any decent shop that does head work (especially on bike heads) will be able to source parts - valves, seats, guides and seals easier and quicker than you, stumbling through the swamp that is the internet of vague & incorrect & conflicting information. May be not much help but fixing 40yr old motorcycles with minimal spares is REALLY hard these days!

Not quite sure what's up with you theses days, seems like most of your posts are just telling people how bad they are, how wrong  they are etc, If you don't like people trying to build a bike these days and can only put them down whether you know them and there skills or not just don't reply if you don't want to help. 

The forum was/is here to help people with there OSS bikes not keep telling them to go and Google it. We all don't know everything and there are some out there who are just starting out on building there first bike. So help out or keep out.