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Biggest bore on a GS1000 ?


FJD

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Hi folks, what´s the biggest bore you can do on a GS1000 engine ?

 

Reason for my question:

Seems like i have bought a block bored out to 78.5mm -- but without pistons.

Seller claims they fit cases without modifications, i will need to find suitable pistons and rings though

Anyone knows what pin size are stock GS rods - and can they handle pistons that size ?

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That's what I have too, means you have to take away material from the crankcases.

 

When you have it running, I guarantee you, you won't regret it!! 78.5mm will give you about 1250cc.

 

Stock pins are 18mm, I ordered pistons from JE, but they fucked up pretty bad.. The pistons are too big for the piston clearence they set for their own product.

Wiseco?

 

I'm not sure, but may be wrist pins for  GSX 1100? I think they have a wall thickness of 3.5mm instead of the 2mm from the GS1000

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Tip for taking away material from the crank cases.

Have a disc made up with the stock barrel size on one side, and the barrel size of the big bore barrels on the other side.

Put a cylinder base gasket over the position bushes with the disc positioned in the base gasket.

Now mark the crank case where to remove material.

 

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13 minutes ago, Reinhoud said:

Stock pins are 18mm, I ordered pistons from JE, but they fucked up pretty bad.. The pistons are too big for the piston clearence they set for their own product.

Wiseco?

I don't know your particular situation but its a bit unfair to blame the piston supplier when its generally agreed that the barrels are bored / honed to size of the pistons not expect the pistons to just 'fit' your holes unless its OEM.

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1 hour ago, Gixer1460 said:

I don't know your particular situation but its a bit unfair to blame the piston supplier when its generally agreed that the barrels are bored / honed to size of the pistons not expect the pistons to just 'fit' your holes unless its OEM.

When I tell JE that I have a bore of 78.25mm for turbo application, than I think I can expect they supply me with a piston with the correct size, because the bore size is leading, you need the proper size of piston rings.

Our expectations of an exact copy also differ, sizes are different, weights are different..

They asked me the size of the wrist pins, and the size of the groove for the piston pins, I send them a sample.

When you have a machine shop, you have the tools to measure what you machined, when you provide a service where you can copy a product, you should have the tools to take the measurements.

It's not like there are 5 different sizes of 18mm wrist pins, or multiple thicknesses of piston rings.. I got a bit nervous when I received those question, and with reason..

 

Their machines are very accurate I noticed, that wasn't the problem, all 4 pistons are the same size, measured with a micrometer acurate to 0.01mm.

 

Quality control in a machine shop is a job on my resume.

 

Edited by Reinhoud
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So block arrived, must be 78.0 bores as my dials show, will get them measuted more accurate and start finding some pistons and rings.

Anyone has some Wiseco, MTC or JE part numbers i can feed google with ?

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On 11/24/2019 at 4:31 PM, FJD said:

So block arrived, must be 78.0 bores as my dials show, will get them measuted more accurate and start finding some pistons and rings.

Anyone has some Wiseco, MTC or JE part numbers i can feed google with ?

There are not really partnumbers for.. 

Send out emails to those companies to get some quotes.

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@FJDif it is a gs1000 8v? Block it will give you roughly 1240cc @ 78mm. Imo it’s on the limit and will have very thin liners. I considered doing this but for my road bike I went with 76mm Kawasaki Pistons from Mtc. Even using gs1100efe liners I had to hand relieve the crank cases. Using any liner that is bigger on the od than a efe liner makes the block very weak and will window out into fresh air between the cylinders, with that you get oil leaks and a very unstable block with which ring life will suffer. 

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2 hours ago, Cheeky4648 said:

@FJDif it is a gs1000 8v? Block it will give you roughly 1240cc @ 78mm. Imo it’s on the limit and will have very thin liners. I considered doing this but for my road bike I went with 76mm Kawasaki Pistons from Mtc. Even using gs1100efe liners I had to hand relieve the crank cases. Using any liner that is bigger on the od than a efe liner makes the block very weak and will window out into fresh air between the cylinders, with that you get oil leaks and a very unstable block with which ring life will suffer. 

It's deffenitly on the limit, but it does work alright.

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  • 1 month later...
On 12/2/2019 at 3:37 PM, FJD said:

Just bought a set of new 78 mm MTC pistons intended for a kwaker GPZ - they have 17mm pins, i will get them machined to 18 mm to fit the GS

they need honing thats all, and zx1100 pistons 78mm are 18mm pin size ;) and barrel wise your better off finding gs1100g as they fit and are bigger externally so No break through (y)

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  • 4 weeks later...
1 hour ago, Brizznasty said:

Use the gs1100 rods on the 1000 crank there 18mm wrist pin then the 78mm gpz pistons. Really good combo about 1260cc. 

 

On 1/2/2020 at 6:49 PM, kiwi said:

Plus should of said it all comes out as 1238cc on 78mm bore :banana:

So which is it? Using longer or shorter rods won't make any difference with capacity unless the crank is stroked / de - stroked !

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5 hours ago, Gixer1460 said:

 

So which is it? Using longer or shorter rods won't make any difference with capacity unless the crank is stroked / de - stroked !

 

6 hours ago, Brizznasty said:

Use the gs1100 rods on the 1000 crank there 18mm wrist pin then the 78mm gpz pistons. Really good combo about 1260cc. 

1100 rods are 1.5mm longer than 1000 rods, 78mm on a 1000 crank will give you 1238cc, 78mm on a 1100 crank will give you 1260cc

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1 hour ago, Reinhoud said:

 

1100 rods are 1.5mm longer than 1000 rods, 78mm on a 1000 crank will give you 1238cc, 78mm on a 1100 crank will give you 1260cc

Thanks Reinhoud hadn't picked up on this and you have explained it exactly spot on (y)

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