gsx750 engine in gs750 frame ?

[TonyGee]

any body put a 16 valve 750 engine in a 1978 gs 750 frame ?  i was just wondering about the engine mounts arangement. 

[wraith]

Not much help, but I've seen  gs750 with a gsx1100 engine, years ago you when you could pick a gs1000 engine for less than £100 because no one wanted them as they where putting the more powerful 1100 motors in 

O how the world has changed 

[TonyGee]

1 hour ago, wraith said:

Not much help, but I've seen  gs750 with a gsx1100 engine, years ago you when you could pick a gs1000 engine for less than £100 because no one wanted them as they where putting the more powerful 1100 motors in 

O how the world has changed 

bloody hell wraith you've let me down their mate     i think the GS frame is a tad longer than the GSX, probably because the kickstart.  

[gorbys]

I put a gsx1100 engine in my 77 gs750. The rear lower fit. And I could bolt in the front one too but it made the engine tilt too far forward so the rocker cover touched the frame. So I made new brackets for the front and the rear upper 

[TonyGee]

1 hour ago, gorbys said:

I put a gsx1100 engine in my 77 gs750. The rear lower fit. And I could bolt in the front one too but it made the engine tilt too far forward so the rocker cover touched the frame. So I made new brackets for the front and the rear upper 

thanks for that, so its best to start with the rear lower mounting point.  

[gorbys]

5 hours ago, TonyGee said:

thanks for that, so its best to start with the rear lower mounting point.  

Here's what I had cut out, the rear ones are a fair bit longer than the stock ones since the engine is shorter. The front ones are almost the same as stock but with the engine side hole higher up to tilt the engine at the correct angle. 

 

[Swiss Toni]

Ah, the ‘Modifiers’ bugbear raises its head once more!
It’s the same old story. Keep the engine to the rear, to combat weight distribution, chain/swinger interface, and you then get header problems. Find a happy medium, Tony. Aim for the ‘sweet spot!’ 

Edited September 24, 2021 by Swiss Toni

[gorbys]

50 minutes ago, Swiss Toni said:

Ah, the ‘Modifiers’ bugbear raises its head once more!
It’s the same old story. Keep the engine to the rear, to combat weight distribution, chain/swinger interface, and you then get header problems. Find a happy medium, Tony. Aim for the ‘sweet spot!’ 

Isn't that more of a thing with the oil cooled gsxr/bandit engines in gs frames? 

[Joseph]

9 hours ago, TonyGee said:

thanks for that, so its best to start with the rear lower mounting point.  

Always will be whatever the swap i think

[Swiss Toni]

51 minutes ago, gorbys said:

Isn't that more of a thing with the oil cooled gsxr/bandit engines in gs frames? 

Usually. But any replacement engine that’s not the same dimensionally, is going to put the onus on the modifier! ‘How far forward/back? More to the left? Maybe the right?’ 

[Jonny]

When I put a GSX1100efe in my 78 GS750, I mounted it underneath using the long bolt from the 750 that runs under through the rear of the engine, then used the 750's triangular front mounts to secure to the downtubes. I had to turn one round the other way I think. Unlike Gorbys, I didn't have a problem with it hitting the frame.

For the rear I used the EFE mounts but had to have one modified (left hand) which involved cutting the end off and welding it back on the other way.  I didn't need to move it left or right.

You can see in the dry-build photo that the engine leans about 1 1/2 inches further forward than the 750 lump, so the exhaust headers had to be shortened, but a GSX exhaust might be okay. It looks in this pic like the rocker cover is touching the tank - but it isn't.

 

Hope that helps.

[TonyGee]

engine's in now   i started with the rear lower mount and made all the brackets for the rest, the engine sits forward in the frame so the exhaust fitted no problem, to get the engine further back it would of meant cutting the lower rear cross member off and re'welding it further back. couldn't be arsed with all that shit but its in, will live with the gap at the back.  

[Jonny]

4 hours ago, TonyGee said:

engine's in now   i started with the rear lower mount and made all the brackets for the rest, the engine sits forward in the frame so the exhaust fitted no problem, to get the engine further back it would of meant cutting the lower rear cross member off and re'welding it further back. couldn't be arsed with all that shit but its in, will live with the gap at the back.  

Tbh with the carbs and K&Ns on, you don’t notice it.

[TonyGee]

pic of engine in.

 

[cnap504]

Sure looks like it fits, the Suzuki engine swap possibilities are tempting.  Let’s say I have a friend who wants to put a 2 valve GS1000 motor in a GS750 frame.  He just missed a very nice (non running but clean and original, arrgh !!) ‘79 GS1000 on ePay US, sold for $1375.  So does a GS1000 engine and 750 frame make a good pair?

 

Edited October 28, 2021 by cnap504

[TonyGee]

27 minutes ago, cnap504 said:

Sure looks like it fits, the Suzuki engine swap possibilities are tempting.  Let’s say I have a friend who wants to put a 2 valve GS1000 motor in a GS750 frame.  He just missed a very nice (non running but clean and original, arrgh !!) ‘79 GS1000 on ePay US, sold for $1375.  So does a GS1000 engine and 750 frame make a good pair?

 

not done it myself but many others have 

[Jonny]

4 hours ago, cnap504 said:

Sure looks like it fits, the Suzuki engine swap possibilities are tempting.  Let’s say I have a friend who wants to put a 2 valve GS1000 motor in a GS750 frame.  He just missed a very nice (non running but clean and original, arrgh !!) ‘79 GS1000 on ePay US, sold for $1375.  So does a GS1000 engine and 750 frame make a good pair?

 

The GS750 is actually the biggest engine (physically) Suzuki made (due to the kickstart mechanism). So the problem isn't ever will it fit - it's what to do with the extra space.

[TonyGee]

24 minutes ago, Jonny said:

The GS750 is actually the biggest engine (physically) Suzuki made (due to the kickstart mechanism). So the problem isn't ever will it fit - it's what to do with the extra space.

i was thinking of making a steel box to fit in the gap, then i can put a pie in to warm up 

[Captain Chaos]

32 minutes ago, TonyGee said:

i was thinking of making a steel box to fit in the gap, then i can put a pie in to warm up 

I'm sure it's been done before.

Looking at you @fatblokeonbandit.

[cnap504]

1 hour ago, Jonny said:

The GS750 is actually the biggest engine (physically) Suzuki made (due to the kickstart mechanism). So the problem isn't ever will it fit - it's what to do with the extra space.

No issues with the GS1000 engine being possibly taller ?

[gs7_11]

5 minutes ago, cnap504 said:

No issues with the GS1000 engine being possibly taller ?

Nope.

[TonyGee]

44 minutes ago, cnap504 said:

No issues with the GS1000 engine being possibly taller ?

question answered above 

[safka]

Nice to see such a fresh topic here. I have a gs75x with a crankshaft bearing shell failure. I would like to find a new working engine there. Has anyone done such a swap and what engine would fit without major conversions?

[Mike711]

BTW if anyone was interested I can confirm it's possible to remove the head & barrels with the engine in situ.

[gorbys]

On 11/21/2022 at 7:08 AM, safka said:

Nice to see such a fresh topic here. I have a gs75x with a crankshaft bearing shell failure. I would like to find a new working engine there. Has anyone done such a swap and what engine would fit without major conversions?

You can fit most gsx engines in gs frames. It's just a matter of making the appropriate mounts. 

BTW I didn't have any issues of fitting an exhaust on mine. Gsx Katana exhaust from hindle. But results may vary I guess.