[TheSteve]

I believe they were 36mm for the gsxr 600. The 1000 is even bigger.

[TheSteve]

Well guys I may be at it again. About 3 weeks ago a new toy dropped into my hands. It's a 1997 GSXR 600. Heres some pics:





It's carbed, but it DOES run, and it runs pretty well. It has a full Yoshi system, geared up a ton (annoyingly so even), and a jetkit (factory pro as far as I can tell). It starts every time and runs nicely, but it has massive lean surging during freeway cruising and slight surging around town. I raised the jet needles to their highest setting and the low speed surging stopped but the freeway issues still remain just enough to be annoying. Unfortunately I don't have the remainder of the jet kit, only what was installed when I got it. Without other jets to toy around with theres not much I can do beyond what I've tried.

Now I'm faced with a dilemma. Do I simply buy the jets required and tinker till I'm satisfied? Or do I provide more entertainment/reading material for you guys and do another EFI swap? Monetairly, getting the proper jets is best. But if you've been following this thread you'll know that money isn't the driving factor for me in something like this.

Since all the pros/cons of EFI are already pretty well known and I likely already have my mind made up I'll start with a few facts:

96-99 GSXRs (known as the SRAD generation) were mostly carbed.
All 600s were carbed.
In 1998, Suzuki started offering the 750 as EFI.
Bearing largely the same engine, I figure the 750 throttles will fit into the 600 intakes.
If I'm wrong, I can retrofit the 01-03 generation's 600 throttles as I did with the Kat.
Intake boot spacing appears to be 82mm between all four cylinders. Cam chain is on the end, unlike the katana.
I don't currently know the intake boot diameter. Haven't had to pull the carbs off yet.
Theres TONS of room underneath the carbs, I should have no problem fitting anything there.
All SRADs had electric fuel pumps. Only the EFI models had high pressure pumps, but they should fit the tank the same (in tank pump)
Stock carbs are Mikuni BDSR36. FSM says the bore is 36.5mm, boots are LIKELY in the 38mm area.

So with that knowledge, I find myself once again considering an EFI conversion. It shouldn't cost very much, the 98-99 throttles are very rare, but seem to sell for $140. MS1 again, $140. Can't find the correct pump right now, but I'm sure one will show for $50ish. Between the 750 throttles probably fitting, the 01-03 600 throttle spacing being identical, and the in-tank pump it should make for a very easy and CLEAN swap. Theres even a spacious trunk on this bike. It's practically begging to be megasquirted. What do you guys think?

[Cheriff]

I say do it. I wouldn't mind reading along as you work on another one of these projects And you have another bike you can ride so its not like you will be putting yourself out if it takes a while to get this one finished.

[sonosam]

I'm with Cheriff on this one. Go for it. I would love to do something like this to the Kat when I get the money and reading along for an older GSXR would be an interesting read. (for me anyway)

Marc

[TheSteve]

I may start a new thread on it pretty soon once I start buying stuff. It does look like on the 98-99 750s the throttle bodies were HUGE so I'm not sure ill be able to fit them. Ill probably be best off with the same throttles as before. Ill keep looking around.

I did find that there are almost none of those fuel pumps available. Bikebandit has them for about $600 so that's out of the question. I may be able to fit a car's pump in the tank with a small bracket to hold it upright.

[scottynoface]

Maybe you can retro an older zx7 fuel pump?

[TheSteve]

That would probably work. The pump looked like the standard cylinder type, just maybe a hair smaller than a cars. I'm sure just about any bike pump will fit

[TheSteve]

I found a spec sheet for various GSXR throttles. The 98-99 750s are huge, with an outer diameter of 54mm. There's absolutely no way those will fit, but the 01-03 generation looks like it'd be perfect. I'm going to measure a whole bunch of stuff on the katana and compare it to the gsxr to see if the throttles I have on the kat would fit. I'm going for zero cutting and welding this time around.

One last thing I forgot to mention. This bike uses a TRUE CDI type system. The primary coil voltage is around 200v iirc. That'll fry the megasquirt, so the tach wire hopefully is compatible. If its not then ill have no choice but to buy the more expensive MS and try to capture the VR signal.

[BrianT]

Sounds like a project I'd like to try ... if I had the money, time, and skills to do it.

[TheSteve]

Well with all the foreseeable parts tallied up its coming to $335. Less if I use an MS I have chilling here, and even less if I gut the katana (not doing that). The breakdown for that is:

$140 for a MS1 2.2 kit
$90 shipped for another set of 01-03 GSXR 600 throttles
$55 for an automotive fuel pump that I could likely adapt to the in tank pump bracket
$30 for intake and water temp sensors
$6 for a weldable O2 sensor bung to put in the exhaust
$15 for misc hoses, filters, wire

Issues:

CDI type ignition WILL fry the MS, so I may need the 3.0 board (VR sensor) for this which adds cost
Need to find a proper mount for the coolant sensor. Only place I can figure is in the radiator where the fan switch was, unless I want to drill and tap the thermostat housing.
Would like to run the stock airbox, so I have to seal the large holes in the box to the smaller throttles.

[TheSteve]

Alright, just spent about $300 on stuff. Actual prices were:

$187 shipped for an MS1 on a 3.0 PCB
$87 shipped for 01 gsxr600 throttles
$5 for the O2 bung
$6 for a frequency divider

Havent bought a fuel pump or the temp sensors yet but I've got my eyes on some cheap. I came up overbudget because I opted for the 3.0 board for the VR wheel. I also found a cheap way to use a 4 tooth crank wheel to control a 4 cyl motor: a frequency divider. It's a chip the size of a dime that mounts into the MS case, and with a few modded circuits itll cut the 8 pulses/cycle down to the correct 4 pulses/cycle. Havent found any documentation on its use in a MS environment but going off the spec sheets it'll be fine. I'll start a new thread in one of the subforums once the parts arrive.

[Cheriff]

and the peasants rejoiced...

[Cheech]

TheSteve, excellent writeup and thank you for blazing the way on this. I saw you included the same essential parts list for the 98+'s, do you or anyone else know of any other gotcha's to do the swap on a post?

[TheSteve]

I think the only thing that'd be different for a post would be the TPS. You'd have to make sure the new and old tps function identically, or put the kat tps on the gsxr throttles. Then T off the signal wire and feed it to both the MS and igniter. Other than that it should be about the same except for possibly different fitment issues.

[Cheech]

Well, it's on. I just ordered a set of TB's from fleabay, going to start amassing parts as budget allows. I'm oscillating between the Microsquirt, MS1 2.2, and MS2 3.0. My friend that is going to help me tune this thing once it's installed is saying a Microsquirt would be preferred since it was designed for motorcycles. I guess I don't really have a true basis for comparison since I don't know what I'm looking for in a EFI ECU to do what I want to do.