851cc Kat?

[loudnlow7484]

Looking at the bore & stroke measurements of the different kats, I thought of a possible project for this winter.......
The katana 600's have the 48.7mm stroke of the long-stroke Gixxer 750's from 86-87 & 90-91.
The katana 750's have the short stroke (44.7mm) engine of the 88-89's.

If you were to slide kat 750 cylinders, pistons, and head onto kat 600 bottom end, and conn rods, could you indeed end up with a 851cc kat?

I'm sure the redline would have to be lowered, say, to maybe 11,500, or 11,000, but I think the displacement difference would make up for it.

I've also considered the possibility that they changed the rods from the gix750 engine to the kat600 engine, so I may have to source rods from a long-stroke gixxer.

My only real concern is.... would the valves contact the pistons from the difference in crank stroke? I suppose sourcing cams from a long stroke gixxer should solve that, all assuming that the 750 pistons aren't taller than the 600 pistons.

I'm hoping someone very familiar with the internals of these things will chime in and tell me if this is do-able, because if it is, it would seem an inexpensive mod, as 600 engines go pretty cheap, and I've already got a 750 engine for the top end.

Thanks.

[loudnlow7484]

Lol, and I suppose I could put the remaining parts together and make a 550cc kat, too!

[Lagmo]

maybe you can clearsomething up for me, since you're so into this

Are 'Slingshot' Kats different to other kats in regards to stroke/bore?

[loudnlow7484]

slingshot kats? over here we had slingshot gixxers, but I don't know anything about slingshot kats. Our kats use the same basic engine as the 88-89 'slingshot' gsxr's, though. But then the 90-91 gsxr's were also referred to as 'slingshot's, and they had the long stroke motor, and 38mm carbs, soooo. I wish I knew more about Suzuki's overseas stuff. I've only known of the short stroke motor used in kats.

[Mr. Clean]

Ok here is the low down on sling shot Kats and Gixxers.

The sling Shot Kat/Gix is ALMOST the exact same engine. The Gix has a smaller combustion chamber and valves. The pistons are the same and interchangeable along with the rods and jugs.

Now for building the 851 Kat I'm actually working on such a project right now. The cc's actually work out to 815 though. What you have to do is use the long stroke rods. You have to have the small end of the rods bored out 1mm to accept the 19mm piston pins of the bigger 73mm pistons. Next you have to use the sling shot jugs and head, but you need to get a special spacer from Cometic Gaskets for the bottom end where the jugs meet the transmission. The reason is the sling shot jugs are shorter and with the long stroke rods the pistons WILL hit the head and valves. Fast Larry over at www.maximumsuzuki.com has built one of these engines, he said it produces a ton of torque at the low ends and has a wicked top end.

[Lagmo]

Mine's a 90' 600 with 'slingshot'... dunno what that is exactly though. I think SweetLou suggested it was for shoot at drunk cagers

[edit]BTW: thanks for clearing that up MrClean any difference in the carbs? [/edit]

[loudnlow7484]

Ugh, not as easy as I'd hoped. Sounds like just snapping up a gix1100, kat1100, or B12 engine will probably work out better for me. I need a project for the winter that'll have me real fast come spring.

[Mojoe]

www.maximumsuzuki.com does not work for me. say page can not be displayed.

a good source for used racing parts is www.dragbike.com
just click on the "photo classifieds link on the right.

[loudnlow7484]

https://www.maximum-suzuki.com

[damic]

I have an 88 Gix 750 motor that I was thinking about doing this with a Weisco 813 kit for an approximate displacement of 900 CCs. I also have an article from Motorcyclist (Feb 93) magazine of a chap named Rich Gerstener who did just this. What I havent found is info on whether this motor lived or eventualy broke a rod. The short stroke rods that I have are slim on the the pin bore side and have no long stroke rods to compare and see if there is more meat there. I'm registered at maximum Suzuki too but I didn't seen anything on fast larry's motor. I will have to pm him and get his input. If you are interested, I have the article in .pdf format so I could send it to you.

[damic]

I forgot to mention that I believe the pre 98 Kat engines are like the short stroke (88-89) Gixers and the 98+ Kat engines are the longstroke (90-91) Gixers. Probably specialK could answer this.

Bore X Stroke lengths

86-87 & 90-92 GSXR
Pre 98 Katana
70.0 X 48.7 mm

88-89 GSXR
98+ Katana???
73.0 X 44.7 mm

[Mr. Clean]

My bad on the link, I forgot the -. Search the fourms at http://www.maximum-suzuki.com/ for "816" or "815" and you sould find some info on the engine Larry built. PM him for faster results. And damic I would love to see that .pdf file, email it to me at [email protected].

[damic]

Mr. Clean
File sent.

Enjoy

[Mr. Clean]

Thanks damic!

[trinc]

damic,

can you send it to me also ?

[email protected]

thx
tim