Boring out GS850

[jahighold14]

Hi everyone,

New to the forum and this is my first post. I'm currently rebuilding a 1980 GS850 and need to have the cylinders bored out. I can have it bored .5mm over and get the parts but I was hoping to go 1.00mm. The only problem is I can't find 1.00mm oversized pistons and it looks like Suzuki has discontinued them. From what I can gather the stock pistons are 69mm with 16mm wrist pins. Wiseco sells the K816 kit for a GS750 that's 70.0mm with 18mm wrist pins that I was looking at purchasing if I could make it work. My questions are:

1. Could I bore out the stock GS850 connecting rods to 18mm to accomodate the Wiseco set or

2. If not, could I run gs750 connecting rods

Thank you in advance for your advice.

Jon

[uk gs nut]

I think you will find that 750 kit is for a 4 valve engine. The 750 and 850 2 valve motors use the same size wrist pins. And the 4 valve con rods are plain bearing high oil pressure, 2 valve are roller bearings and low oil pressure.

[jahighold14]

Thanks for the quick response. If that's the case do you know of any aftermarket options? Could I run gs1000 pistons and a set of standard rings?

[Nessism]

Easiest and cheapest way to go is to purchase a low mileage cylinder/pistons and then bottlebrush hone the cylinder and install new OEM rings. Suzuki sold a bazillion 850's so finding good used parts (less than 20k miles) isn't overly difficult. Use OEM gaskets during rebuild too, not aftermarket.

[uk gs nut]

1000 piston use 18mm pins, so that's off the table also. I agree with Nessism find good used parts.