efi conversion?

alright guys i got an idea ive been tossing around in my head… ive been thinking about converting my engine to efi i have a honda vf1000r engine and iam tired of the constant tuning to my carbs. what should i do run a single throttle body per cyl like the carbs? or build a plenum and run a single larger throttle body?[:D]

Individual throttle bodies will be more efficient than a large single throttle body. Seriously though, why hasn’t anyone done this before? This engine is a perfect candidate for EFI. Might even pick up 5-15 HP in the process! I have a set of GSX-R750 injectors and throttle bodies laying around…hmmmm I wonder what a Kalmaker or Megasquirt ecu could do with that? And think how easy it would be to remove the throttle bodies compared to the carbs.

yep its something i had thought about, although i have not as yet done any research on it, would be interesting to see how the vfr800 system works.

VFR800 would be an ideal donor for this, it would probably require very little modification to fit in the V nicely, would have the required throttle position sensors etc, air cleaner would be fairly straight forward, 110 bhp from 782cc, but from 998cc? It appears that the injectors would certainly be in the ballpark, and if running a Megasquirt or similar, they can be made to work a little harder by either increasing the duty cycle or fuel pump pressure or both, certainly worthy of consideration.
Any EFI gurus here?

yes exactly! individual throttle bodies would be a great idea and i was thinkin about using the vfr style intake and throttle bodies… the only problem i would have is trying to get the angle of the intakes on the vf1000 to match up to the straight intakes from the vfr and yes megasquirt would be a definite… i have been seeing some throttle bodies off of some bmw bikes that individual throttle bodies… this would be the first efi conversion to a bike i have ever done… but i have done 100+ efi conversions on many types of offroad trucks… i have also done pfi, tbi, efi, propane conversion and custom alky injection (would be awesome on this bike) LOL but toss me ideas i could maybe build a conversion to sell on the market…

For a VF1000 the ideal would be the MicroSquirt unit, and since you have converted offroad trucks, it is exactly the same principle on a smaller scale. Even if the VFR800 throttle bodies are not viable, then individual throttle bodies (read not linked together) would be able to be link-aged together to work as one. The GSXR throttle bodies I mentioned are interesting for the fact that they have two injectors per cylinder. One primary injector for ride-ability and a second as supplemental for wide open throttle. What do you think?


I’m pretty much keeping up with the thread, but apart from servicing lines and filters, my own fuelling expertise probably extends to rebuilding twin SUs on a Mini or an Austin 1800 - & I’m not sure if i could even do that anymore!

I think that the only way to set it up is to arrange a dummy engine to fit everything to. It may still not be viable, but worth a try I think.

My initial reaction is “Why” ? The carburation on the standard VF`s is not bad is it ?
I can understand the interest from technical challenge aspect ( which is a good enough reason ) but apart from that…


Normally if implemented correctly, efi can provide better fuel metering which “should” translate to lower fuel consumption and more power.
I agree that the carbs do a fairly good job, but for how long will carb parts be available? I don’t know but when most of our bikes are 25-30 years old, it won’t be for much longer I would think.
If a Kit list could be made up and even some base maps provided, it could keep our old v4’s going for a fair bit longer.
The trouble is finding someone who knows enough about it to source parts that are common enough and priced reasonably.
Quite a lot of car parts are interchangeable such as temp sensors, map or maf sensors, cam angle or crank angle sensors, 02 sensors etc.
The ecu side of it can be, as mentioned a Microsquirt which you can build yourself or buy assembled. That really only leaves the throttle bodies and throttle position sensor/s.
Admittedly it sounds like a huge undertaking, but this would not be hard at all for an EFI specialist once the parts are sourced and fitted, which is why I mentioned an engine to dummy fit everything to.
One suggestion would be to find a cheap small 4 cylinder donor car of around 1.0 to 1.4 litres in capacity like a Vauxhal Corsa? (Holden Barina if in Oz) with suitable EFI components and a set of VFR800 throttle bodies.

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sorry i aint been on here much i have been really busy with work and iam moving across states now… but ia have come up with a idea using a micro squirt system, nothing but a map sensor, crank sensor, o2 sensor, and water temp sensor. i have also been working on some custom throttle bodies that run a linkage system equivalent to a triple 6 pack on a mopar. i have also come up with injectors and special aluminum weld in injector mounts that run individual fuel lines and not just a injector rail (making mounting the injectors easier). i figured i could take the same mapping and fuel patterns off of a vfr and run that on the microsquirt system and get me pretty close. with maximum efficiency i have come up with the numbers that with cruising i will get about 55-58mpg and up to 125-127 bhp at 10,000rpms WOT… soo all in all completely worth the challenge! yall agree?

Sounds like you have been very busy, your idea is good, as simple as possible and using proven components. The idea of individual throttle bodies is interesting, do you “need” a throttle position sensor? I think it would be great to see an EFI VF1000, I just don’t have all the skills required.
Regards, Tony

you could use one… but if u have a good crank sensor u can get away without it… i might run 2 on the #1 throttle body just for shits and giggles but i want to make this as easy as possible so not only can the average person do it but also easy to track down failures… the trick i wana do is make an ecu mapping so precise that i can unplug a vital sensor (simulating a failure) and the engine still run just like limp home mode on a standard car. so that way u can still make it home when on a long trip.

Some good logic there Cam. Simplicity is the key, once it is sorted in a simple format, then you can try improving things with TPS and 3D ignition etc. I think a VF with 125 hp would be loads of fun, what torque figures do you anticipate?

I`m salivating as I read this thread - keep going guys.


I’ve been considering the EFI mod myself but I’m definitly too busy these days…

sorry i aint been on here in a while again… but still workin on the efi… i have also been making adapter plates so i can run the vfr style supercharger and also a 50 shot of nitrous to go with it… on the efi itself iam expecting to possibly get a little over 130hp and possibly 100lbs of torque… with the supercharger and correct A/F ratio iam lookin at maybe… 150-160 with an extra 120-125 lbs of torque… then nitrous an extra 10-15 hp… my goal? 200mph thats it…then im done LOL

Hi from Down under. I have a 84 VF1000r, engine & frame only 2 apart. now thats close for a factory number. Any way I have a VFR800 engine and electronics including injectors.

I like whats been discussed but my 1000r engine goes in the shed and Im fitting a VFR800. Yep EFI, yep gear driven cams. yep cheap to replace and modifications and parts easier to source. Now a Supercharger.Thats the aim, but the standard VFR800 with a tune and system etc has to be the go and the original motor ,the irreplaceable motor sits in storage. Still a challenge but im thinking better all round . Supercharger optional. Does this sound feasible over trying to re invent the wheel, whoops sorry EFI?


Or since its 8 yrs ago did it ever come to fruition>