FZR/YZF head and carb boot measurements.

[Freestyle72]

Hey could i ask a favour from you guys? I am looking for some measurements off the FZR and YZF heads.

I am looking into a fuel injection conversion for the YZF head. Basically what i need to know is the measurements:
- between the carb holders from center-center-center
- Inner diameter of the carb boot
- Boot height

I have ravaged the internet, I know the YZF carbs a 36mm, but is that 36mm I.D. or is that the actual size of the boot. So let me know what you guys come up with. And of course I will most likely be doing a D.I.Y. guide after I am done for the EFI conversion. Hopefully it will only cost about $300 for everything.

[DonTZ125]

What are you planning to use? I've got a set of '03 R6 TBs & a '07 fuel pump. It was seriously annoying to discover the rack didn't fit between my frame rails!! (FZR250R)

Two plans under consideration - #1, pull one TB out, condense the rack to three (1 / 2-3 / 4) inlets; #2, pull the injectors and TPS, modify the fuel rail to fit in line behind my 4 stock carbs (4x TBI, kinda). The ECU is a MegaSquirt II running MSII/Extra 3.0.3, full-sequential injection and COP ignition.

That's the plan. I have most of the bits; all I need now is some damn time to work on it!!

[Freestyle72]

I was planning on either FZ6 throttle bodies, or 03/04 R6 ones. The other ones i was considering GSXR throttle bodies, but I need some measurements on the YZF head to make sure it will space alright etc. I think I am going to use MS1 and do the most basic thing and upgrade if I think i need to. I read about some guy fuel injecting his 95 ninja...which I also have and he bought MS2 at first, and then actually went to MS1. Basically I think I am going to run GSXR or R6 throttle bodies, which ever fit best, then MS1 with use the R6 TPS, remove secondary butterflies although I wish i could use them, and then just do IAT in airbox and read MAP from the air box, or just one of the boots. The other thing I thought about was running the carb holder vacuum hoses all to one container and then read MAP from there. That just leaves me with coolant sensor being the last thing I need. Although I am not yet sure how to get a proper RPM measurement. I don't think there is any cam position sensor, so I would have to go with a reading of the coils or something and correct it? How are you getting around the need for a cam or crank position sensor?
BTW nice to see some canadian around here. I am from london, but living in hamilton for now.

Also I am wondering how big of a deal it would be just to respace the Throttle bodies my self, that way I can just use whatever is cheapest. But modifying the fuel rail seems kind of complicated/annoying. What do you think?

[DonTZ125]

I'm fairly certain your TBs will need to come together, not further apart. The Gen2 R6 TBs don't have much in the way of spacers. Also, since the R6s are side-drive for the cam chain, they're also evenly spaced, without the big gap in the middle we're used to. One point to correct - the Gen2 R6 TBs don't have secondary butterflys; they're CV units, with vacuum-powered slides. That's actually what drew me to them initially, since they're so grossly oversized (compared to my stock carbs) I'd have massive throttle control issues otherwise. And yes, no matter what you do, modifying the fuel rail will be somewhat complicated / annoying. That's why I'm considering going with the 3-TB reduced rack - there would be no respacing, just cutting off and blanking the end where the 4th item once lived.

There is a crank position sensor under the timing / stator cover. I haven't pulled my timing cover off to confirm - perhaps one of the peanut (cover) gallery could chime in - but I believe our alternators have a 4-1 tooth pattern on them. If this is so, then you can run off the stock pickup coil through the VR input circuit. Are you planning to use the 2.2 or 3.0 board? The 3.0 isn't that much more expensive, compared to some of the extra features.

I am planning to add a cam sensor for sequential injection and ignition, but you could just as easily run standard batch firing. The new MSII/Extra 3.0.3 code allows 4-channel sequential and semi-sequential injection and firing. The cam sensor is R6, of course - I have an entire harness to play with. I was originally going to use it as a connector donor but now - with IAT, CLT, TPS, INJ, IGN all being hooked up via R6 connectors - I may actually condense it and use it as my MS harness to communicate between the engine and the ECU, and just use the stock FZR harness for lights and charging.

On the topic of charging - look into overwinding your stator, and replacing every bulb you can with LEDs. The Gen 2 R6s use CDI ignition and some LEDs, and have 300W alternators. The Gen 3 R6 ('06+) are TCI (like the FZR) and *ALL* LED, and still need something like 420W to run everything. At the suggestion of Reelrazor, I'm seriously looking to switch to CDI. Much less power-hungry....

The MS has a MAP sensor on the main board; basically, you plumb tubing back to it. The R6 TBs have a MAP sensor already plumbed, but then you'd have to make sure you have the calibration coefficients sorted out. I have a thought in mind to tee-off some tubing between the MS MAP sensor and the R6; use a syringe to suck and blow, then measure and compare the output signals of each unit. Three data points should be enough to get the engine working, then you just calibrate the VE tables to suit. Big point I just noticed in your post - MAP is NOT read from the airbox. It is read from the intake boots DOWNSTREAM of the butterflies! If you try to read MAP from the airbox, you may as well not bother.

[Freestyle72]

Haha you are right the map sensor idea was not thought through. I will take it from the boots. And I forgot the r6 were cv style like carbs, I got the spacing for the r6 throttle bodies off of msefi.com, but as long as the yzf are spaced farther apart I can respace mine without too much fuss, although the fuel rail will be a whore.

Are you gunna run two TBs then 1 for cyl 1&2 and 3&4

[DonTZ125]

1-2 / 3-4 was my original thought, but 'siamesed' (intakes where intake event B immediately follows A - or even overlaps!) is a real SOB to dial in properly. The first cyl tends to get more fuel than the second, leading to rich/lean issues. I'll probably run the 1 / 2-3 / 4 arrangement; since the 2-3 intake events are evenly spaced 360 deg apart, there should be no issues. The ideal would be 1-4 / 2-3 with 2TBs, but I'm not sure I have the skill (or room!) to sort out intake runners like that.

Since the TBs are bigger than the YZF carbs, and the YZF has the wider center gap, you might be close enough to just use eccentric intake boots.

Worst case, you space your TBs, make your measurements, then head down to the local speed shop and get them to fab you something custom.