Big Bore for 600

[Guest]

At the risk of seeming to lazy or to cheap to do an engine swap, does anyone know of a big bore set up for a 90 Kat 600 ?
Have to do the rings anyway so I was just thinking, why not bore what I can.

[Mr. Clean]

Get a set of 90-92 jugs and pistons for a 750 GSXR. You *can* use your 600 head but you will get more power with a 750 for the same years. If i remember right the 90 600 has the shim type valves so a top end from a 90-92 GSXR will work, just reuse your cam shaft gears. You should be able to pick up a set of jugs and pistons cheep on eBay.

Don't use a top end from a 750 Kat though, it is the short stroke engine and you will have to do a lot more work to get it going. And I do mean a LOT. the GSXR is a direct bolt in change.

*EDIT* Suzuki did make a 0.5mm overbore kit kit for the pre 98 600 Kats but it is hard to come buy and EXPENSIVE. IMHO not worth the money when you can just make it a 750.

[SlytlyDeranged]

Mr. Clean, I have a top end for a 750 Kat and was going to attempt putting it on my 600 lowerend. WHat work do i need to do to make it work?

[Mr. Clean]

Mr. Clean, I have a top end for a 750 Kat and was going to attempt putting it on my 600 lowerend. WHat work do i need to do to make it work?

Well I would take the pistons and jugs to a machine shop and have the jugs honed just to make sure they are still in spec. make sure to buy a new OEM set of rings for the pistons, don't reuse old rings! Get 4 new wrist pins and circlips too.
I would have the head torn down and a valve job done on it. Put new oil seals, springs, and retainers in the head. Buy a new spring steel head gasket from Cometic Gasket and a new base gasket from them as well.
Don't forget a new valve cover gasket and cover bolt O-rings.
And most of all, BUY A OEM SHOP MANUAL!!! The OEM manual get very specific on tearing the engine down and putting it back together, you will be very happy you have it!.

All in all you are going to spend about $100-150 for machine shop work and another $150-200 in gaskets and sealers. The springs, oil seals, retainers, piston rings, and wrist pins will run you an easy $200-250 for OEM parts, but you can get them cheaper from www.ronayers.com

[damic]

If it is a pre 98 Kat 750 it will have the same configuration as the 88-89 gsxr 750 which is a big bore/ small stroke motor. this would make a nice upgrade to what would be equal to an 820cc motor. The work that clean was talking about requires you to take out the connecting rods (splitting the case also required) and have the wrist pin end of the rod bored and honed to a larger 19mm. This has been done with nice results. Whether the work is worth it I don't know. I have an 88 gix at home in pieces and was thinking of doing this build with a Wiseco 3mm overbore for nearly a 900cc motor. After totaling up the projected price. I ended up buying a Kat 750 off of ebay for less than half that price. Maybe after I put the new motor in I will take the old 600 and the Gix pieces and do it at a later date.

[SlytlyDeranged]

Thanks for the info guys! Clean, I agree completely with the new rings and gaskets. Wouldn't have dreamed of reusing the old ones. figured while I was in there I would get new rod and main bearings as well.

Damic, thanks for the info about having to get the rods bored to 19 mm. I think the work will be well worth it in the long run. Talk about a nice sleeper!!

Thanks again, I have a new project to start now!! the wife is gonna love this one. LOL She thought I was almost done with my Kat! Muuuahhhahahahaha
Is there any such thing as ever bding done??

[SlytlyDeranged]

Cometic doesnt list a base gasket but I can get one from Ron Ayers. Should I get a 600 base gasket or a 750 base gasket? Should I match the cylinder or the bottom end on this one, or does it matter?

[Mr. Clean]

Get a 750 gasket. Before you start ordering parts I need to make something clear.

The 1988-89 GSXR 750 is a short stroke/big bore engine known as a "slingshot." The 1988-97 Kat 750 uses a slingshot engine as well. There are differences in the tranny between the two but I'm not going to go into that. The sling shot motors have a shorter block that the standard 1986-87 and 1990-92 GSXR 750s ans Katana 600s. You *can* use the sling shot top end on a long stroke 750/600 bottom end but you MUST get a spacer to raise the jugs up 4mm or your pistons WILL hit the valves, and that is BAD. You also must get the small ends of the con rods bored and honed 1mm as Damic to use the bigger sling shot pistons. If you want to do just a straight top end swap a set of 88-87 or 90-92 jugs and pistons will bolt straight up to a 600 lower end. If you have forked type rockers I recommend the 86-87 GSXR head, if you have the shim type head I recommend the 90-92 GSXR head.

[damic]

I figure the base gaskets should look alike to the crankcase, it's the cylinders fitting into them that should matter. If you are serious about building a hybrid motor than send me your e-mail address and I can send you a couple of articles on doing the build.

[Mr. Clean]

Yeah the crank case doesn't care what gasket it gets, the jugs on the other hand need a 750 gasket because the piston sleeves go through the gasket down into the crank case, and 750 jugs won't fit through the holes in a 600 gasket.

[SlytlyDeranged]

I am serious about doing it. My email is [email protected]

[damic]

pdf files

SlytlyDeranged,

e-mail sent.

Enjoy