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77 750 engine in 81 650 frame?


Aphex

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Hello everyone! 

 

So I've had this 1977 GS750 for years and years now. I tore it apart and founf out it was bored over and had high comp Pop Yoshimura pistons in it. 

 

I decided to upgrade the suspension to fit the engine, so I drilled out the frame and installed a GS1100 swing arm for wider tires. I also picked up GSXR USD forks for the front and GSXR wheels all around. Life got in the way and I never finished the project. 

 

However now I have a complete and very sweet looking GS650, from what I've read the 650 and 750 engine are pretty similar. Are the engine mounting points similar as well? Has any one dropped an 8 valve 750 engine into an 8 valve 650 frame?  

 

I really want to get that 750 engine going again as it was just a total monster. 

 

Let me know if you guys want any more pics of both bikes. 

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1 hour ago, gsx said:

If you still got bike in picture two , finish it and forget bout the 650 

I do, but I still need to figure out how to get the rear and front sprocket to align.  As well a ton of other things to do, the 650 is ready to ride. 

 

 

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58 minutes ago, eightball_hotrod said:

+1

+2

As to the 750 into the 650 frame, I believe the 750 engine is much bigger than the 650. You can put a 1000 into a 750 frame and the other way around and you can put the 850 top ends on the 750 motors.

You can put a 650 top end on a 550.

As to your chain align, is it the 5.5" rear wheel? If so you can use a gsx1100f power screen rear sprocket carrier which will give you more room in the swing arm and will bring the chain in to words the wheel, doing this on my ET project and using a 520 pitch chain. I'm told you can also use the gs500 (twin) rear sprocket carrier, but you will need to change the carrier bearing.

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