GS550 with 650 block

[msdosp1mp]

I've searched and found the thread that discusses the details. Is it possible to use the 550 head with the 650 cylinder block? Or is the compression ratio going to be too high. And if it is possible, should I use the 550 head gasket or the 650 head gasket.

Thanks,
William

original thread

http://www.thegsresources.com/_forum/showthread.php?t=84029&highlight=gs550+650

[msdosp1mp]

Either way, I'm going to see how it pans out thru experimentation. I just purchased a used 1981 650E cylinder block, and now looking for some pistons. Are the wrist pins and clips the same on the 550 as they are on the 650 pistons?

Thanks,
William

[tkent02]

If you want to bore it out, 750 pistons fit.

[msdosp1mp]

Which cylinder head should I use?

[tkent02]

The one that fits the best.

[msdosp1mp]

Ok, so what would my compression ratio be if I used the 550 head with the 650 pistons? Would the clearance between the piston and the head ok? Or should I find a 650 cylinder head.

[msdosp1mp]

I'm going to move this to the "Performance" section.

[Suzuki_Don]

To start with 550 wrist pins will be too short. Use the ones from the 650. Also use the 650 head as it has swish chambers that match the 650 pistons and are the reason this motor makes good power.

[brveagle]

If you want to bore it out, 750 pistons fit.

Oh really now? Without major modification, i beg to differ.

[msdosp1mp]

I'm going to stick with the STD pistons and just do a good hone. The block I've got is in great shape. Wouldn't the compression just be terrible with 750 pistons?

[tkent02]

Oh really now? Without major modification, i beg to differ.

How major?

[brveagle]

How major?

Dremel the combustion chamber in each head or throw in a block spacer.

Both of which causes you to start to play with the combustion and compression ratio.