Carb Compatibility Question

[89katana750]

I am planning on using my 89 kat 750 carbs for my 1990 gsxr 750L engine.

What I got was a rebuild kit with all the o-rings, gaskets, and float needle. What I still have to get is the main jet.

What else is there that I am missing?

are the pilot jets, jet pilots, jet needles and needle jets interchangeable?

Not sure on the compatibility, some stuff listed on bikebandit are the same part numbers, but others are different.

if anyone has any experience with these tiny parts, it would help huge. Thanks.

[Anonymous]

jsut use you 89 kat carbs and engine boots and start there you might have to change main jets to make up for the gix motor compression diff and cam differenace

[89katana750]

I will try that. I know that the main jets have to be changed from 110's to 127.5's.

We'll see how it goes, I'm going to recheck my haynes to see the differences in the needle jets and pilot jets.

[89katana750]

I have checked my haynes manual and this is what is the difference between the 1989 - 1997 GSXF 750 AND 1990 - 1992 GSXR 750

Katana --- Main jets - us cylinder #3 110
all others - 105

Main Air jet - 0.5mm

Jet Needle - 5EZ62

Needle Jet - Y-1

Pilot Jet - 32.5

Pilot Air Jet - 1.35mm

Started Jet - 37.5

90' GSXR 750 ----- Main jets - 127.5

Main Air jet - nos. 1 and 4 0.9mm
nos 2 and 3 1.2mm

Jet Needle - 5ZDZ3

Needle Jet - 0-8

Pilot Jet - 37.5

Pilot Air Jet - 1.2mm

Starter Jet - 40


If anyone knows what these numbers mean other than the main jets, and how they work, let me know. Its a big difference eh? Im not sure what to do now, getting all the small parts would equal more than to just get gsxr carbs. what do you think?

[Special K]

You can just about skip all the interchangability and try just your regualr Kat 75o carbs for starters. I'd changed the main jets for best mid range & top end performance though........

If you need a set PM me & I'll send you a set around 127.5 - just pay the postage!

You'll find that most of the other parts don't swap...............size matters!


Then.........after you dial them in with a set of carb sticks and get them runnign right, consider getting a jet kit.

[The CyberPoet]

Since you PM'd me and asked for my opinion:

Take the OEM carbs and have the various jets handy, throw in on a dyno with an EGA (exhaust gas analyzer) and tune it on the spot. As long as the velocity through the carbs isn't too radically different (i.e. - as long as the airflow doesn't slow too much and doesn't move backwards for too much of the stroke at idle as the valve overlap occurs), you should be able to configure the OEM carbs with sucess. I'd suggest having a spare set of diaphram springs on hand as well, to snip down about 1/4th to 1/3rd, if you find it's bogging coming off idle.

Cheers,
=-= The CyberPoet

[89katana750]

Stupid question but,

Do Jet Kits come with all of the o-rings you would get with a rebuild kit?

[The CyberPoet]

Do Jet Kits come with all of the o-rings you would get with a rebuild kit?

No, it comes with none of them.

Cheers,
=-= The CyberPoet