600 Kat hop up tricks...

[XRacerX]

I have done some searching and just not finding what I am looking for...

If you were building a 600 Kat motor for roadracing on a budget, what would you use? Are there aftermarket cams? Are their secrets about other stock Suzuki cams that work wonders (ie 750 cams or ????), has anyone used the carbs (36mm) off of a gsxr 750 or 1100? Im looking for any info other than porting the head, decking the head, 5-angle valve job.

I dont even know what size of carbs came stock on these, im guessing 34s?

Thanks in advance for any help... Id be glad to run some KatRiders.com stickers on the litter critter when she is all done...

[XRacerX]

Hey all... new to this site. The reason I stopped by, is to get some info on the 88-89 GSX 600 Katana motors. I race old GSXRs in WERA Vintage, and am building a 89 GSXR 750, but going to put a 88-89ish 600 motor in it to race in the lightweight class. I have other old GSXR race bikes also, but just about have enough spares to build this little critter. It will race against FZR 400, FZ600, EX 500, RZ 350s, Ducati 750SS, and the like. I am here to get info on what years the motor are the same and such.. thanks... glad to be here..

Sooo... .if I have a 89 gsxr 750 motor (748 short stroke bastard). It is the same as the Kat 750 motor.. .right? What is the easiest way to make this a 600? Can I just use 600 pistons, cylinder and head.Has anyone ever tried to do this?

Okay.. .
600 vs 750.. .deck height the same? just smaller bore?

Rod lengths? Rod big end dia.?

bore/stroke 600 vs 748?

I know this is a lot of ???? thanks for any help...

Im not sure its even legal to down-size a 750 for this class, just seems the easies given what I have to start with.. .

[Anonymous]

your cant make that motor a 748cc motor into a 600 its the wrong one you need a 600 motor or a 90 91 92 93 gixxer motor and use 600 pistons and cylinders the 90+ gixxer 750 and all 600 use the same stroke as do the new 98+ kat 750 and 600 so find another motor would be the best bet

[XRacerX]

your cant make that motor a 748cc motor into a 600 its the wrong one you need a 600 motor or a 90 91 92 93 gixxer motor and use 600 pistons and cylinders the 90+ gixxer 750 and all 600 use the same stroke as do the new 98+ kat 750 and 600 so find another motor would be the best bet

Well.. .I cant really use a 90 or up gsxr motor, that would be too obvious. Must be pre 90. I guess I will need a 600 motor then.

Any chance the 600 or 90-92 GSXR 750 rods have the same big-end as the 748s? I know, Im reaching here... just hate not being able use what I already have... damn...

[XRacerX]

Ive been doing a bunch of searching... and it seems the early 600s were just sleeved down 748s. is this correct?

But they used different rods?

Im not trying to bug you guys... just getting a grasp here...

[Anonymous]

no the 600 is a sleeved down 86 87 motor or a sleeved down 90 91 92 motors. the 748 motor is specail to 88 -89 gix and all 89-97 kat 750

[loudnlow7484]

In truth, if you have a 748 motor, even if it has issues, you could likely sell it, and buy a fully functional 600 motor with the money. 600 motors are plentiful, and relatively cheap.

I'm sure somebody here would be willing to take the gixxer motor off your hands!

[Court93kat]

If you get an early 600 Kat motor with the longer stroke you can install the GSXR 90-91 771 kit from Wiseco and also 750 GSXR 90-91 cams will fit in too.

[Special K]

Check the numbers on that motor, and ask someone on here with a 88 or 89 to check their engine numbers............

I might have a 600 Kat engine here that would work.......just need to verify engine numbers to get the 88 or 89...........

[XRacerX]

After talking to a few people racing in the class, I have come to the conclusion that this is not going to be the best combination. Its still going to be very heavy compared to the competition.

Im not giving up though. It seems a few guys are running later motors (uncompetitively) so no one is asking any questions. We do play by the 'superbike' rules, so you can port, polish, deck, mill, grind on anything... LOL..

So... Im wondering if the 86-87, 90-92 head is a direct bolt on for the 600. I would guess the 750 would have bigger vales than the 600, so that would be much cheaper with some porting than trying to completely redo a 600 head. Im also guessing that the bandit motor with be a 'shim' head, so I will prob need a 90-92 head. I have 36 CVs off of a 89 750, and another set off of a 91 1100 (GSXRs) that might work on a 600 with some compression, and 750 head.

So... then I started thinking that if I did all this, it might make 80ish hp??? and it might get protested, or just break 2nd gear. So it might just make more sense to use a 86-87 750 motor with 600 pistons and cylinders, but retain the head. I would hope the GSXR 750 tranny would be stonger than the 600?

I have a set of Mikuni 38RS flatslides as well as Keihin 41 FCRs, but no matter what I do to a 600, they will just be too big.

I guess my biggest question at this time, is... will a 750 head (749) be a direct bolt on to a 600? Im guessing it would be, since the cams are interchangeable and the bore is the same (before sleeving). But then, where the head meets up to cylinder, the cumbustion chamber dia woudl be too big?...

Thats all for tonight... thanks for any input... those pesky FZR400s with FZR600 motors with YZF 600 heads are making over 100hp at around 350lbs.. bastards...

So then, this one time at race camp....