[philwecksr]

I found 89 gsxr750 boots on ebay... Don't bid against me

[TheSteve]

Just found these if youre interested.

http://cgi.ebay.com/ebaymotors/1989-Suzuki-GSXR750-GSXR-750-89-Carburetor-Intake-Boots_W0QQcmdZViewItemQQcategoryZ35597QQihZ015QQitemZ250244041142QQrdZ1QQsspagenameZWDVW

Ends soon and I'm not ready to buy just yet if you want them. Just make sure that you dont get a pre-88 750 boot. The carbs changed size a couple times on the GSXRs, all the way down to a 31mm on an 86 750.

Edit: Lol we just found the same thing

[philwecksr]

Just won them. I'll start fitting again when they get here...

[TheSteve]

Ok, throttle bodies arrived today. Few things I noticed:

1. The spacing isn't nearly as bad as I thought it'd be. Looks like something as simple as washers between each body would work.
2. Not quite sure what to do with the fuel rail. It looks aluminum so I can't weld it. Would something as simple as cutting it and extending it with high pressure hose work? Theres also the company (ross machine racing I think) mentioned on the GS conversion site that makes custom length rails as another option.
3. Throttle cable. The GSXR unit has a very long travel cable in relation to the Kat. I've got a few ideas, but open to suggestions.
4. The outer diameter doesnt look that far off my stock 33mm carbs. Even those were a tight fit, so some trimming will be necessary. Or find more 750 boots.
5. I took the secondary butterflies out, mostly. The rod is still in because I don't feel like wasting my time sealing all of the 8 holes the rod is gonna leave if removed. Stepper motor and throttle plates removed though, cleaned everything up nicely.

This doesn't look like its gonna be that hard after all.

[Kila-Beave]

On the motorcycle forums @ www.msruns.com there's a guy who turbo'ed a '96 Kat 600. Apparently he used '04 GSXR throttle bodies.

But be sure to take a bunch of notes and pictures of the install as you go. This is something I've been thinking about trying!

Good luck!

[TheSteve]

I completely forgot about pictures, I'll go take some now as well as more as I make progress. I probably won't post them until the end though unless you wanted something specific

[philwecksr]

Well, the bigger intake boots came today. I'm not 100% certain they are even going to work, still a 4mm difference in size so we'll have to see. I think with the right motivation they might be forced on though...

[TheSteve]

Ok, took some pics. Contrary to what I said 10 minutes ago, I'll post some pictures now. I found something interesting:



The Kat 600 intake boots DO fit. Its a really tight fit, but they fit. You have to have the boots off the engine and press them on with a good bit of force but they fit without tearing or distorting.



Heres a picture showing the difference in intake port spacing between 01-03 GSXR 600 TBs and Kat 600 33mm carbs. You cant see it, but cyl 1 is lined up perfectly.



Heres a comparison of overall height. You'll have to use your imagination for the carbs, as mine are mostly disassembled.



Picture of both side by side:



Picture of secondaries removed:

[philwecksr]

Yeah I did the same. The 750 boots slid on with some dish soap. A snug fit like you said, but it works. I can rotate them freely so when I put them on the bike I'll have some freedom...

I'll let your pics suffice since I don't have anything more than you do...

[TheSteve]

Got a few more pics. I separated the 4 throttle bodies and test fitted them all. It's not a bad fit at all. I ended up dremeling out the intake boots to save some hassle in the future so now the TBs slide in without much difficulty. You'll notice in the pics that the long bolt on the top is in place, meaning that the bodies are pretty much straight. The bottom one might take a little bit of persuading to fit, but I didnt try yet.






So all thats left to is extend the throttle linkage (should be easy enough), figure out the throttle cable, and extend the fuel rail (not sure). Not too bad at all. Still need to order a fuel pump and the MS unit. I've been waiting on the MS since I can assemble one of those in about 6 hours so I can do that last minute.

Forgot something, I need opinions on what to do with the secondary butterfly shaft. You can see the long side fell out as I was separating them, and you can see the holes left behind. Should I just put it back in and call it a day or do you think I'd be better off sealing the holes up. Ideas for that:
1. Tap the holes, thread bolts in
2. JB weld or some other glue as filler
3. Cut the shaft, and use sections of it glued in place as the plug

I doubt itll make much difference either way so I might just leave it. At the same time it looks nicer with it gone.

[mdbonjr]

Great job you guys, keep us posted, I'm inspired. TheSteve, I say tap the holes, JB weld in some short round head bolts, and dremel the threads off the inside leaving the intake cleanly open to the butterfly. I'm not positive, but you might could find some aluminum bolts which would eliminate the bi-metal corrosion.

[TheSteve]

Alright, more updates. The throttle cable is taken care of, and the fuel rail is ready. The throttle cable was an interesting problem. The cable on a GSXR comes in from the bottom, and has a much longer throw. So the Kat cable mounted in the stock GSXR location wouldn't release the throttle more than 1/2. The choke cable had the correct throw but is much too short and lacks the adjustable end the throttle cable has. So I decided to grind the coating off the GSXR part so it was down to bare steel and weld the adjuster nut of the Kat cable in place. An alternative to welding would be to make a bracket that holds the cable up above the throttle bodies. The location I picked to weld to was the throttle stop. Its far enough back to allow full range of motion, but close enough to the resting position to let the throttle bodies rest on the idle adjuster.




Next up is the fuel rail. The rail needed to be extended by about 8-10mm to fit up with the spaced out throttle bodies. Since the rail was useless to me anyway, I figured I would try and extend the rail by cutting it in half and using a fuel hose to bridge the gap. First I took the chop saw and cut the rail in half. Doesnt have to be perfect or even a clean cut. Then I took the angle grinder (because I don't have a bench grinder, much superior tool for this) and ground down all of the casting marks. I kept at it until I had a nice smooth mating surface. This is the part you need to be careful on; if the rail isnt smooth, you're almost guaranteed to have a fuel leak. I ground both sides, measured, and it looks like I need 1/2" hose.

I started with this



After cutting



Both done


You aren't going to find EFI rated hose (65+psi) that large, so youll have to make do with something like heater hose. Chances are good that the heater hose won't last too long at those pressures, so I plan on covering the length of the hose (1" - 1.5") with hose clamps to prevent bursting. Much like steel braided hose, but cheaper and available anywhere. I'll let you know how that works out.

Mounted up


Gap


Gas tank clearance:

Note on this pic, none of the rubber bushings are in place, so the tank is a little lower than normal. Should be plenty of space afterwards, but I dont have the petcock or level sender installed right now.

[mdbonjr]

Wonder if you could take the fuel rail to a machine shop and have them thread those ends you cut and make you a threaded coupler? Is there a thread sealer that would hold 65+ psi? That probably wouldn't cost more than $40-50.

[TheSteve]

Maybe. Worth a shot if this doesnt hold. One of my goals on this project is to do everything relatively cheap, so I'm trying to do as much of the work myself as possible. Theres probably some sort of adapter I can thread into the existing holes, as the rails are soft aluminum. There was also the custom rail mentioned awhile back, but I thought Id give this a try first

Another interesting observation:

I saw a picture of a GSXR fuel pump earlier. It appears to have the same bolt pattern as our Kat's fuel level sender unit. Maybe instead of messing with inline fuel pumps we could just throw one of the GSXR units in the tank. Wonder if the gas gauge would still work or if the ohm range changed.

[TheSteve]

Found a measurement, GSXR pump is too big. I'll stick with the inline pump, it may be a little more expensive but its probably the most reliable solution.