FZ6 throttle body spacing


DoctorG

New Member
Hi guys,

I'm converting an old carb bike to EFI and I'm looking at some FZ6 throttle bodies. Does anyone know the spacing of these ITB's? I'm considering the 2003 model version.

Based on my research they are 36mm at the butterfly. Are there any variations to the size through the model years? FZ6R any different?

Lastly, do these run a FPR in the fuel line or built into the pump?

thank you
 

Rumpig

Member
The FZ6 and FZ6R throttle bodies are interchangeable, the outside diameter is the same it's the inside diameter that is different. 36mm for the FZ6 and 32mm for the 6R. You'll need an ecu to run it all. Pic is 6R throttles.throttle bodies.jpg
Pressure reg is part of the pump I believe.
 

DoctorG

New Member
Thanks a lot for the info. Based on that pic I'm gonna guess they're around 75mm spaced apart. Mine are 77mm so it should be close enough.
 

DoctorG

New Member
Thanks for that. I already bought these and they're in the mail :/

Just measured my carbs and they're 75mm. So I'll make up the 1mm on each port in the adaptor plates I have to cut that bolt the yamaha boots to the kawi head. The zx636 itb's were 75mm so in retrospect I should have gone that route - but the FZ6 sets on ebay were all more complete, as in the injectors, harness, tps, tps plug etc was all there. For some reason most of the zx ones were missing a component here or there and buying those seperately adds up.

Another bonus was the fz6 has a metal fuel rail which is easier to modify (I need to space out the itb's between cyl 2&3). I also need to turn the fuel rail into a through-flow rail with an external fuel pressure regulator.

thanks again. Will update this thread with pics once I receive these if anyone is interested.
 
Thanks for that. I already bought these and they're in the mail :/

Just measured my carbs and they're 75mm. So I'll make up the 1mm on each port in the adaptor plates I have to cut that bolt the yamaha boots to the kawi head. The zx636 itb's were 75mm so in retrospect I should have gone that route - but the FZ6 sets on ebay were all more complete, as in the injectors, harness, tps, tps plug etc was all there. For some reason most of the zx ones were missing a component here or there and buying those seperately adds up.

Another bonus was the fz6 has a metal fuel rail which is easier to modify (I need to space out the itb's between cyl 2&3). I also need to turn the fuel rail into a through-flow rail with an external fuel pressure regulator.

thanks again. Will update this thread with pics once I receive these if anyone is interested.
I love your optimism here but even if you have a whole bike to poke at this is not going to be a slam dunk.
The two throttle bodies are paired as sets. You may be able to seperate the pair, but the units are one.

You need 36.6psi, a trigger wheel and CPS sensor, vacuum, air and water temp, and I hate to say but you will have a hell of time making the ecu think it should run your engine....
I say this as I have a complete wiring harness and ecu on on the floor before more and it won't fuel and spark in gear as it wants to see the proper gear ratio from the transmission which uses the CPS and 3rd or 5th gear on the trans output shaft to know fueling and gear maps for a given condition.

I'm not wanting to discourage you but there is more to this than meets the eye.

On this forum there is a thread Advancing the timimg IIRC started by Rumpig which leads to 600riders.com and a thread i started called Playing w/trigger, winter project. Take a look at those. It may give you some insite.
 

DoctorG

New Member
Thanks for the links. Will check it out.

What ecu are you using? I have a full standalone wasted spark system that i will wire up to a oem zx10 24-2 trigger wheel and pick up sensor. A signal amplifier will then read that into the ecu, which will trigger the coils and injectors. I cant see why it shouldnt work. The whole thing will run off tps only. I may rig up the water temp on th ecu to the bike's oil temp and have it mapped accordingly to compensate for cold starts.

For fueling i will use a walbro inline fuel pump, gravity fed through the old petcock valve.

The spacers for the head to itb will have a slight offset in them to split the narrow "pairs" of itb's into the intake ports that will be slightly wider. 1.5mm per port should be ok. Just means a slight angle on entry vs a straight shot.

Main reason for all of this is that i dont know or understand carbs, and i dont want to ever be stuck and not know what to do.
 
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Im not sure if hot linking will work after server/software update but...

The shafts will never turn again if you cut and seperate these into 4 parts....

Im not sure if hot linking will work after server/software update but FZ6 injectors are a light orange. Like so:




 

DoctorG

New Member
I get what you're saying but I'm not planning to separate the two pairs of ITB's into 4 individual ones.

They will only be seperated between cyl 2 & 3 where the linkage is. I'm also not using any of the IACV components.
 
Sounds like a fun project!
My reference is stock S2 07-09 FZ6 ecu... so apples and oranges. It seems like a must have to me but vacuum is the only measure of load imposed. So that, TPS, CPS, and cylinder head temp would make up the vitals. Oil temp takes to long to come around in most where the cylinder temp is near immediate.

You might look at some stand alone AFR monitors to check fueling for a while. Plenty out there and cheaper than a new engine.
 

DoctorG

New Member
Yeah it wont be as sophisticated as modern bike tuning with load and timing per gear etc. But it can't do worse than the carbs right? The ECU supports vacuum but without an airbox (which I'm trying to avoid) that won't be an option.

I will probably get an AFR gauge yes. The aftermarket management system I'm using supports closed loop lambda which I may use if I see AFR's aren't where they should be.
 

AL72

Member
The electronic fuel injection needs data from a lot of sensors (not present in carbureted engines) to work properly, is that correct?

Regards!
 

DoctorG

New Member
The electronic fuel injection needs data from a lot of sensors (not present in carbureted engines) to work properly, is that correct?

Regards!
you basically just need a timing pulse trigger for rpm, and a TPS signal. That's the minimum and will allow the fuel pump, injectors and coils to fire.

water, air temp and various other sensors just allow finer tuning, easier starts, correct fan trigger etc. But it's not critical. I've run many car efi systems with aftermarket ecu's so this shouldn't be any different.
 
Curious, why not use the IACV assembly? Its simple, effective, and it works. Granted it wants hot water for a warm idle but that can be over ridden as it unbolts.
Because those venturi's have no provissions for idle air I am wondering what your plan is.

Good luck!
 

nik_555

New Member
hello to all, am new here. i have problem please help me. i have yamaha fz6 the engine bad starting but if starting good working Does not take turns, am change full kit trottle position sensor but not working,
 


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