GSXR Throttle Body Experiment: Meat and Potatos

Posted: June 30, 2011 in Uncategorized

Here’s the update:  They friggin work!  I did get them to run alright with some modifications to the KPa indexing on my fuel/timing maps but I decided to ditch the speed density tune and go with a alpha-N tune.  I’m still sorting it.  I also am going to add a GSXR idle solenoid and use the MSextra closed loop idle function, I just bought the electronic components needed to make that work.

So far my impression is that everything improved- idle, mid range, top end, throttle response, sound…everything.  Idle ain’t perfect and thats why I want to add the solenoid, then it should be perfection.

this blog post is going to be about all the goodies I had to get, where I got them, and how much for my particular setup.




  • MS1 v3.00 unassembled kit $200
  • 12′ harness from DIYautotune $69
  • walbro w/ install kit $115 from DIYautotune
  • GM IAT sensor/pigtail, DIY $17
  • Coolant temp sender, Bosch came on my core motor 😉
  • 5.75″ 36-1 trigger wheel with a 1.5″ center hole $37 shipped from ebay
  • 89 Ford mustang VR sensor w/ pigtail $10 ebay (same exact pigtail as the COPs)
  • AEM UEGO wideband 30-4100 $180
  • 3 relays, fuse block, terminal strip, mounting board, MSD vibration mounts, harness material, vac line, wire, shrink tubing, zip ties, ect…$100-150ish
  • 5/16″ fuel line, Jegs 25′ for $17
  • fuel return bung welded onto the fuel tank local $20
  • header was used and already had a bung on it…free 😉
  • FPR bosch Ljet, was on the core motor…free 😉
  • fuel filter, summit racing $12
  • MSextra firmware…free;)
  • Tuner Studio registered copy…$40 and well forth it for the VE Auto Tune function

Grand total is $1255.  Thats not bad at all considering CB wants $1800 for their EFI kit(they don’t have a distributorless ignition system either), and I have seen ITB’s that bolt onto IDF manis go for $2000 just for the throttle bodies.  I am considering upgrading to MS2 and going full sequential, that will add even more throttle response to my setup.

That’s all I got for now, next post will include updates on the alpha-N tune and how that idle solenoid worked out…stay tuned.


  1. Greg Blythe says:

    Hey Ninja,

    lovin the FI setup. I have a 62 notch that needs more bodywork than I have time for at the moment, so I’m getting started on the engine. Just picked up a 2.0L type 4 from a 77 bus. I want to similarly experiment with the GSXR throttle bodies. Found a set on ebay ’08-’09. Didn’t realize they had two butterflies and two injectors per TB. can a megasquirt control all of this? looks like 8 total inj, and a driven set of flys…

    Is it possible to repurpose the ecm from GSXR, as I also picked up the harness and cops.

    keep up the great work…mad scientist!

    • Sweet Greg, a nice and early notch. Now that I got the motor where I want it, I’m planning to do all the welding on mine too.

      most of the gsxr TB’s have 8 injectors from 05/06 on, and they all have dual butterflys. To be able to use the gsxr ecm you will need a cam sensor and need to make it programable, i’m not too sure how much control a Power Commander will give you but I know they cost $300, so a MS would be cheaper. You can use all 8 injectors with MS but it will be bank/batch fire. If you get the lower inj’s flow tested you might be able to just use those. If they are too small then you could also upgrade to some Siemens-Deka 60lb pico injectors, they are cheap too $54 ea and that’s plenty of flow even with 10-12 psi of boost, muahahahhaa. I removed the secondary throttle junk, it’s a linkage nightmare after you seperate the two throttle bodies and we don’t need it, even though it would be cool to set it up as a choke.

      I have some serious mileage on this setup now and found some weaknesses to my design and possible solutions. It’s time for a new blog entry!

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