RC36.2 (4th Gen) Fuel Injection discussion

I'm thinking about injecting an RC36.2 and hoped we could have a good technical discussion about it here.

First of all:-

I realise that the RC46 throttle bodies won't just drop on.

Durbahn has injected an RC30 and a 400. However I believe he used the Motec system.

I have also read (here?) of someone using MegaSquirt on a V4.

But...

It seems to me that the RC46 injection is way closer to what is required than either Motec or MegaSquirt and MUST be cheaper than either of those. So I'm pondering the possibility of modifying the RC46 throttle bodies to fit the RC36 and use the RC46 ECU, with a Dynojet PC or Rapid Bike module to 'tune' the ECU's delivery to suit the different motor, although I'm thinking that it probably would actually run without either. Not well enough to use, no doubt, but it would sure help development if you have something that runs.

The throttle bodies will take a lot of modification, but that surely must be easier than trying to manufacture something from scratch. They'll need to be split apart, mounted in the correct relative position and suitable linkages and fuel pipes made. Tricky, but as I said, has to be easier than starting from scratch and there would be a readily available wiring harness too - RC46.

Another very tricky task would be to add a Cam sensor probably requiring accurately positioning and welding something to a cam. However, maybe the existing output from the RC36's Ignition sensor could be used as the CranK Position sensor. Everything else is external and can be simply added to the bike, plugged into the RC46 wiring harness which would have all the right connectors.  :smile:

I notice that the 5th Gen FI system uses an atmospheric pressure (BARO) sensor, but that is no longer used on later VFR's, nor any other bikes I briefly checked. But if the ECU needs it and the wiring harness has the connection (yes to both), then the BARO sensor can be plugged in and used.

So there's 3 major issues I see here.

1. Modifying the RC46 throttle bodies to suit the RC36 intakes.

2. Creating a Cam Position Sensor

3. Using a Power Commander to modify the ECU's control sufficiently to suit this engine.

I'm pretty sure 1. can be done. 2. can definitely be done, but I'm less sure about 3. I see no actual reason why not, but it would largely depend on the range of adjustment afforded by the add-on management module (PC or other).

Please don't ask WHY? No point arguing about that. But apart from that, what do others think about this?

I understand the why and wont ask that, myself, I would be thinking it might be more successful getting an FI engine from a later bike and installing the whole deal in the gen 4.

BiKenG, I admire your optimism. The oe VFR800 ECU may be persnickety if it doesn't see everything normally connected - the instrument panel for example. To minimize had scratching, it seems prudent to avoid any unnecessary complications so deep-6 the Pc or other modifier 'til after you are able to fire it up. Ideally, you have a running donor bike to play around with before committing surgery.

Camshafts rotate at half the speed of the crankshaft so that is probably a no-go. The cam sensor also requires accurate positioning. 

Another task will be fitting the fuel pump into the 4th gens tank, along with the supply and return lines.

Btw, the boys at Mighty Car Mods have fit FI to a lot of projects (none motorcycles, sadly) but they provide some context. They use aftermarket ECUs from Haltech which greatly simplifies tuning & set-up.

https://www.youtube.com/user/mightycarmods  (look for parts 7 & 9 of Gramps the 11 Second Car) Actually if you have time watch all their videos.

http://www.haltech.com/tech/

Good luck, I look forward to your odyssey.

7 hours ago, bykemike

I understand the why and wont ask that, myself, I would be thinking it might be more successful getting an FI engine from a later bike and installing the whole deal in the gen 4.

No-can-do, BM, the RC36 and RC46 motors are too different physically. You'd have better luck trying to swap bodywork, i.e. no chance at all. Or at least no chance to have anything other than a dog's breakfast as a result.

Well this should be interesting , I like watching projects like this take shape. 

Or to quote Lorne "looking forward to your Odyssey"

For reference, here's a set of RC36 carbs next to a set of RC46 throttle bodies:

[image: 20160705_091722x.thumb.jpg.b914a03fa19538b571168a7a135b0a41.jpg]

Ciao,

13 hours ago, bykemike

I understand the why and wont ask that, myself, I would be thinking it might be more successful getting an FI engine from a later bike and installing the whole deal in the gen 4.

I thought about and looked into that, but it wouldn't be trivial. Cut the S/A pivot boss off the back of the 800 engine for starters and then most of the mounting points don't line up so quite a lot of reworking the frame to make it fit. Even then you'd have to mess with the airbox, so no advantage there.

But also, I like the idea of the 750 engine. Nicely symmetrical compared to the 800 and I think a fun project to inject it.

Don't get me wrong about the 800 engine. I do like that also and have other projects going on involving a couple of those, so in some way, I also wanted this to be a 750 to differentiate it.

6 hours ago, Lorne

BiKenG, I admire your optimism. The oe VFR800 ECU may be persnickety if it doesn't see everything normally connected - the instrument panel for example. To minimize had scratching, it seems prudent to avoid any unnecessary complications so deep-6 the Pc or other modifier 'til after you are able to fire it up. Ideally, you have a running donor bike to play around with before committing surgery.

Camshafts rotate at half the speed of the crankshaft so that is probably a no-go. The cam sensor also requires accurate positioning. 

Another task will be fitting the fuel pump into the 4th gens tank, along with the supply and return lines.

Btw, the boys at Mighty Car Mods have fit FI to a lot of projects (none motorcycles, sadly) but they provide some context. They use aftermarket ECUs from Haltech which greatly simplifies tuning & set-up.

https://www.youtube.com/user/mightycarmods  (look for parts 7 & 9 of Gramps the 11 Second Car) Actually if you have time watch all their videos.

http://www.haltech.com/tech/

Good luck, I look forward to your odyssey.

The dash is really simple and the ECU doesn't care about whether it's connected or not. I've not decided on dash for this bike yet, but won't be OEM VFR.

I'm building this from a separate engine and frame (that I already have), so I'll just buy the bits I need rather than butcher any existing bike.

The FI system requires a CranK Position sensor and a CaM Position sensor. The former will be very accurate to determine the exact position of the crank. The latter will be far less so, but is required to establish on which part of the stroke the engine is on as that cannot be determined from the CKP sensor output which is used to provide the ignition timing. The ECU can simply control the timing of the spark relative to the CKP sensor output, but also knows when it's TDC and when it's top of the exhaust stroke from the CMP sensor output and in this way there's no need for any wasted spark.

What I'm not sure about is how it decides when to open the injectors. That's less critical than ignition timing and could use the less accurate CMP sensor output, but I think it's more likely that the CMP sensor is only used to determine the stroke and it's the CKP sensor output that is used to accurately determine when to spark and/or squirt. However, to a certain extent it's irrelevant. There will need to be CMP sensor and I'll need to figure out how to add that. Durbahn's site will help there as he's done it for the RC30 and a 400.

In any case, assuming the ignition pulse of the 750 can be used as the CKP sensor output the CMP sensor is the only one that needs to be added to engine.

I was thinking of using an 800 fuel tank, which has an internal pump of course. Might drop straight on. Anyone tried this?

I'm not imagining any of this will be simply swap and fit from other bikes. I WILL have to manufacture parts for the throttle bodies assembly and the cam will need welding etc, but I have the equipment.

There are various ECU options if I don't go with the 800's. Durbahn used Motec and could provide ready made working maps to start from, but there are others, although probably have to start from scratch creating the maps. I still think the 800 ECU and a PC would be the simplest.

5 hours ago, JZH

For reference, here's a set of RC36 carbs next to a set of RC46 throttle bodies:

...

Ah, so clearly the carbs are a larger bore than the injectors. Hmm. Durbahn used GSX-R 750 injectors which are larger and may therefore be better. But, I am more interested in mid range torque and ride-ability than outright power, so the smaller injectors might be a better bet. They flow enough for acceptable power on the 800, so really, they should be enough on this 750.

Re-joining the bodies for the different spacing and angle will be one problem, but the intake rubbers will be another. Durbahn had some specially made. That'll be something to consider at a later date.

In fact, if I use the throttle bodies with the same OD as the carbs, I could use the 750's original intake rubbers. You know the next question John. Could you possibly measure those ODs? How well would a throttle body fit in the 750 intake rubber?

BTW, this is not a short term project. I also have several others I'm working on and this is more a case of as and when I get time. So don't expect rapid progress.

Well, it's only 748cc vs 781/2cc, innit?

Forget rubber, why not do something with silicone hoses?  Use some good clamps and I can't see the injectors going anywhere.

Yes, I was kinda expecting that... I have now located all of my carbs in the shed, so I will have a look.  (The RC36-II set I mentioned earlier is missing one of the 16016-MZ2-E00 mixture screws.  At least I think that's the part number--TBC.)

Ciao,

1 hour ago, JZH

Well, it's only 748cc vs 781/2cc, innit?

Forget rubber, why not do something with silicone hoses?  Use some good clamps and I can't see the injectors going anywhere.

Yes, I was kinda expecting that... I have now located all of my carbs in the shed, so I will have a look.  (The RC36-II set I mentioned earlier is missing one of the 16016-MZ2-E00 mixture screws.  At least I think that's the part number--TBC.)

If the throttle bodies are close enough to the carb's diameter, it ought to be possible to just use the RC36 rubbers.

That part number is I think wrong, but if you can let me know the correct part and I can look into getting one for you in exchange for the loan of the carbs in order to get it to first run.

Ken,

As you mentioned having a welder and other tools to fabricate with, if you have a lathe you could possibly make up some adapters to go between the hose sizes. If the OD's have a large enough difference you could even look at offsetting the smaller side as much as possible to prevent splitting the RC46 throttle bodies. Pair that with some silicon hoses and it might work. Just a quick thought, someday I will have the tooling, space, and time to do builds like this.

A member here was looking into doing this some years back, pretty sure they were trying to fit GSX-R throttle bodies to a 4th Gen. IIRC the topic petered out without the motor ever firing up.

I stumbled across this NC30 Fuel injection project:

https://blog.familjenjonsson.org/blog/2015/05/22/microsquirting-the-nc30-part-1-of-many/

A long but detailed account.

-Gordon

6 hours ago, The Phantom

A member here was looking into doing this some years back, pretty sure they were trying to fit GSX-R throttle bodies to a 4th Gen. IIRC the topic petered out without the motor ever firing up.

That's what Durbahn used, but he no doubt wanted power so the GSX-R's 45mm throttle bodies were appropriate. I always try to use Honda designated parts if possible and I have a spare set of 800 throttle bodies, so that's a big incentive to make use of those.  :biggrin:

One reason to NOT use those is that they are cast together in pairs which means trying to change their relative spacing would appear to be harder. But, on the other hand, the cast 'web' between each choke in a pair could be cut and then used as the mount on to which could then be bolted something to space them as required. Since these webs look kinda flat, that might open up the way to use some simple carbon fibre sheet cut to size which would be stiff enough and nice and light. Then something else between the spaced out pairs to suit the V and intake angle of the RC36 motor.

A big plus is that with the 800's throttle bodies, injectors, ECU, sensors and wiring, it ought to run. A PC can then be used to clean up the ignition and fuelling. Simples  :unsure:

But still just tossing ideas around in my head at the moment.

8 hours ago, coupedupsubie

Ken,

As you mentioned having a welder and other tools to fabricate with, if you have a lathe you could possibly make up some adapters to go between the hose sizes. If the OD's have a large enough difference you could even look at offsetting the smaller side as much as possible to prevent splitting the RC46 throttle bodies. Pair that with some silicon hoses and it might work. Just a quick thought, someday I will have the tooling, space, and time to do builds like this.

First step will be to find out if the 800's throttle body will fit the 750's intake rubbers. But I don't have the 750 engine to hand at the moment so it'll be a few days till I can do that.

Another thought. The RC36 intakes changed size did they not, from 3rd to 4th Gen? Are the rubbers also different?

https://www.bike-parts-honda.com/honda/model/VFR/750.html

Simpler to use GSXR TB's, they are seperate units on the late 90's ones, mounted like carbs on a rail, so would be better suited to fitting as replacements.

16 hours ago, Mohawk

Simpler to use GSXR TB's, they are seperate units on the late 90's ones, mounted like carbs on a rail, so would be better suited to fitting as replacements.

I'm not convinced they would be simpler. I'd have more to do figuring out how to assemble them in the correct rigid layout. Besides, I really think the larger choke diameters would not work in my favour and require far more of a change to fuelling from a basic 800.

Probably a better option would be to use those from a CBR900RRY (929). They are similarly separate units, 40mm and also from Honda :-)

At the end of the day, I'll probably use whatever best suits the RC36's inlet tracts and rubbers.

What's the difference in the intakes of the VFR versions, i.e. the Gen 3 to 6?

I can confirm that the 5/6th gen rubbers are the same, but the TB's are different, with different injectors.  Not sure on the 8th gen, but its 6th gen motor retuned, so should be the same.

No idea on the carbed ones.

Fallen at the first hurdle unfortunately. It would appear the 800's throttle bodies are significantly larger than the 4th Gen carbs :-(

There's no way that I can see the injection TB fitting into a 4th Gen intake rubber. I pushed hard but it's not even close. Also the internal shape is wrong as it partially obscures the actual injector. The 800's intake rubbers are shaped around the injector to not obscure the fuel pulses, but of course the RC36 intake rubbers don't have that.

I also tried to fit the 800's intake rubbers onto the 4th Gen intakes. It's closer, but not ideal. They slip on very easily of course as they're basically too big and they don't grip the intakes at all. There's a mm or more of movement side to side - until you tighten the clamp screw. It is actually possible to squeeze the rubber onto the intake stubs. They're then quite firm although it is possible to twist them around if you grip them well and try hard enough. The stubs seem longer than the 800's as the rubbers are not snug up against the head. There's a gap. However, that wouldn't matter if the rubber can form a good tight seal onto the stubs. I think a better type of screw clip would have a better chance of getting a good seal. But I'm not sure of the long term implications of the rubber being compressed like that and whether any possible good seal would last.

So, 4th Gen intake rubbers are a non starter (damn, just wasted £25 on them) but 6th Gen rubbers are a possibility, although not ideal. So the search is still on...

Do any of the pervious carb models have a larger intake/carb diameter than the 4th Gen? That might help.

Taking a good look at the 800's TBs, the way they're cast is not how I remember from previously and separating them won't be as simple as I thought. May be impossible depending on if there's any internal cross passageways I cannot see. Hope not, but anyway I started looking at alternative TBs.

First of all I discovered that the 929 FireBlade seems to have 2 pairs, just like all the other Hondas and not the 4 separate units as I have seen stated and as I mentioned in a previous post in response to Mohawk. So whoever wrote that is simply wrong.

As Durbahn discovered, the GSX-R750 is a good candidate with 4 individual TBs. But at 45mm intake ID they'll make the rubber matching problem worse. Unfortunately, although the GSX-R600 uses smaller TBs that might fit nicely, they also use ECU controlled secondary butterflies and that's just not gonna work with the VFR.

So nothing's falling into place at the moment:-(  Just have to keep looking.

JZH, 30/11/2017 at 8:58 AM

For reference, here's a set of RC36 carbs next to a set of RC46 throttle bodies:

[image: 20160705_091722x.thumb.jpg.b914a03fa19538b571168a7a135b0a41.jpg]

Ciao,

Puzzling that despite what JZH's picture seems to show, those TBs on the right will NOT fit into the intake rubbers for the carbs on the left as the TBs are so much bigger. Really doesn't look that way in the photo. Mind you, I was trying it with 6th Gen. TBs. Could they be bigger?

But it does explain from where I got my previous optimism about splitting the TBs. The 5th Gen. TBs as shown above are the ones I first thought about splitting and it looks entirely feasible. The 6th Gen. ones, not so, hence my more recent less optimistic, post. Not only are the castings less favourable to splitting, but also the upper intake connection to the airbox is siamesed on the 6th Gen, but separate on the 5th Gen. which is far preferable.  No reason to not use 5th Gen. TBs on this 750 project so I just need to find some 5th Gen. TBs to cut. Don't 'spose you want to sell yours John?  :biggrin:

As far as I know the 6th Gen got 8 point injectors but then upped it to 12 point in 2006. At least the parts list shows different part numbers for the injectors themselves which supports that. However how can one distinguish between TBs with 8 point injectors and the later TBs with 12 point injectors. Obviously counting the injector holes would be tricky, but is there some other way to identify TBs as early or later 6th Gen?

One other question to which someone might know the answer - Is it possible to fit the later multipoint injectors into the 5th Gen. TBs? Usually the whole TB is swapped if you want the later injectors, but would they actually fit? I suspect not, but don't have both here to try it. Anyone know the answer?

I sense another trip down the garden to my shed is imminent!

The throttle bodies pictured were acquired solely to harvest their injectors, which were then professionally cleaned and used on my yellow 5th gen in California, so these TBs have no injectors.  If you want to try them with 6th gen injectors, feel free; I have no use for them, so you're welcome to them.  I'm happy to help your projects in any way I can.  Some of my spare parts made their way into lovely Rick Oliver's RC30/36 some years ago, so no pressure there!  (The bike's original injectors are still in California, sorry.)

ISTR Dan from A&A Performance experimenting with 6th gen injectors on the Torocharger bike, but ultimately he decided the 5th gen injectors were fine.  That suggests that they can swap, but I don't remember the details, really.

Btw, the RC36 carbs in that picture are from my FL; FR-V carbs are 2mm smaller, I think--and they are definitely different in many other ways (I had not realised that until I compared the set I have here with that picture.

Ciao,

1 hour ago, JZH

I sense another trip down the garden to my shed is imminent!

The throttle bodies pictured were acquired solely to harvest their injectors, which were then professionally cleaned and used on my yellow 5th gen in California, so these TBs have no injectors.  If you want to try them with 6th gen injectors, feel free; I have no use for them, so you're welcome to them.  I'm happy to help your projects in any way I can.  Some of my spare parts made their way into lovely Rick Oliver's RC30/36 some years ago, so no pressure there!  (The bike's original injectors are still in California, sorry.)

ISTR Dan from A&A Performance experimenting with 6th gen injectors on the Torocharger bike, but ultimately he decided the 5th gen injectors were fine.  That suggests that they can swap, but I don't remember the details, really.

Btw, the RC36 carbs in that picture are from my FL; FR-V carbs are 2mm smaller, I think--and they are definitely different in many other ways (I had not realised that until I compared the set I have here with that picture.

Ciao,

Aha, first of all, yes those TBs will be perfect to try and fit, thanks, much appreciated.

Secondly, very interested to hear what you say about the 3rd Gen carbs being bigger - music to my ears. Since 4th Gen rubbers are too small to accept the TBs, there's hope that 3rd Gen rubbers may be better, i.e. actually fit.

I need to find a good (i.e. flexible) set of 3rd Gen rubbers and try to squeeze those TBs in.

I've been building and riding Do-It-Yourself Fuel Injected motorcycles for about 10 years now.  One of my best efforts is my 1993 Suzuki GSF400.  Instead of trying to retrofit/modify a set of throttle bodies from another motorcycle I simply turned the GSF400's rack of Mikuni BST32SS carbs into fuel injection throttle bodies.  This keeps the fit and serviceability of the original setup which really helps in the areas of long-term ownership and maintenance.

I did a little searching and found that the secondary injectors from a Kawasaki ZX-6R (the set that's mounted on the intake airbox) were a perfect match for the fueling needs of my GSF400's little 100cc displacement pistons.  So all I had to do was remove all of the excess plumbing and metal from the float bowl area of the Mikuni BST32SS carbs and get a receiving pocket machined into each of the four carb bodies (with the tip of each injector aiming up into the carb bore just beyond the throttle butterfly.  After some experimentation I removed the carbs vacuum operated diaphragms because performance was unaffected.

I fabricated the necessary bracing to locate and secure the ZX-6R injector array into the newly machined injector pockets.  And I added a Throttle Position Sensor that was parted-out from a Triumph Speed Triple.

[image: DSCF0195_zpswvhamwkn.jpg]

[image: DSCF0386_zpsotkpcdlg.jpg]

[image: DSCF0492_zpsamrmvz0e.jpg]

[image: DSCF0493_zpsrpmdwtkn.jpg]

[image: DSCF0496_zpsqjujbg9s.jpg]

[image: DSCF0497_zpsgw0sbr67.jpg]

Just an example of one possible pathway to a successful Fuel Injection project (I use the Microsquirt V3 ECU).

Why try to stick with the Honda ECU when the Microsquirt V3 ECU offers you almost unlimited user-control over every input and output parameter?  You'll be able to fine tune every single aspect of your 4th Gen's fueling and ignition.  There are moments when you feel like a mad scientist (when it's your fabrication and tuning that make is happen).

There's even a way to achieve Full Sequential Injection Control without a camshaft position sensor (using the Manifold Absolute Pressure signal from cylinder #1, which is just as reliable as a camshaft position sensor).

7 hours ago, GreginDenver

I've been building and riding Do-It-Yourself Fuel Injected motorcycles for about 10 years now.  One of my best efforts is my 1993 Suzuki GSF400.  Instead of trying to retrofit/modify a set of throttle bodies from another motorcycle I simply turned the GSF400's rack of Mikuni BST32SS carbs into fuel injection throttle bodies.  This keeps the fit and serviceability of the original setup which really helps in the areas of long-term ownership and maintenance.

I did a little searching and found that the secondary injectors from a Kawasaki ZX-6R (the set that's mounted on the intake airbox) were a perfect match for the fueling needs of my GSF400's little 100cc displacement pistons.  So all I had to do was remove all of the excess plumbing and metal from the float bowl area of the Mikuni BST32SS carbs and get a receiving pocket machined into each of the four carb bodies (with the tip of each injector aiming up into the carb bore just beyond the throttle butterfly.  After some experimentation I removed the carbs vacuum operated diaphragms because performance was unaffected.

...

Aha, I've been thinking along those lines too, using the VFR750's carbs and I believe an early Kawasaki 900/1000 (I forget which) had a similar injector rail with suitable injectors. I've not discounted it and will be looking into that and the MicroSquirt for a similar project to inject a CBX1000 (6 cylinder), but that's further down the line. For this VFR750 I kinda want to make it as Honda as possible, so priority will be to see if I can use the 800 parts. If I can't use those TBs, I'll look for alternative TBs and if that fails, then it's modify carb time and a different ECU.

But it's always interesting to see what others are doing to inject their bikes, even more so with regard to my CBX project.

How does the MS use MAP sensor output to detect engine position? If the MAP sensor is connected to all intakes, how does it know which pulse is for which cylinder?

BTW, why did you choose the MS over say Motec?.

7 hours ago, BiKenG

How does the MS use MAP sensor output to detect engine position? If the MAP sensor is connected to all intakes, how does it know which pulse is for which cylinder?

BTW, why did you choose the MS over say Motec?.

The Firmware load that the MegaSquirt and MicroSquirt use is Open Source, so guys are free to be creative. 

Your question about the MAP sensor is a perfect example: One of the problems with fuel injecting motorcycle engines is that they are always configured with Individual Throttle Body arrays (both carbs and throttle bodies count).  Individual Throttle Bodies are great for high-revving performance applications (most motorcycles) but they produce a very poor and messy vacuum signal to a MAP sensor.  So running a single MAP sensor is always a bit of a problem.  A guy in Germany has developed a build-it-yourself, advanced Multiple-MAP-sensor unit that uses an Arduino Nano to monitor four MAP sensors (one for each cylinder on his ZX-7R).  The code loaded into the Arduino Nano looks at all four MAP sensor signals and determines which is pulling the most vacuum at any given microsecond.  Then the Nano forwards that signal to a Digital-to-Analog converter which is wired into the MicroSquirt's main MAP sensor input.  Also, the Nano knows which of the four MAP sensors is connected to cylinder #1, so whenever it sees that particular MAP sensor pull its highest vacuum it (the Nano) generates another digital output that mimics a camshaft position sensor (again out of the Nano as a digital signal, then through a DAC and on to the input on the MicroSquirt for camshaft position).

I see, so there's a MAP sensor for each cylinder. I have a funny feeling Honda MAP sensors are rather expensive, but I guess he's using a more cost effective sensor.

All food for thought re the CBX, but is another reason for grafting the 800s injection onto the 750 as provided it can physically be done, then it's relatively simple as there's a ready made wiring harness with all the required sensors and just the one ECU module. No other ancillary electronics required. Well, apart from a Power Commander or equivalent. At least I assume it will need some tweaking, although just have to see on that once it's running.

1 minute ago, BiKenG

I see, so there's a MAP sensor for each cylinder. I have a funny feeling Honda MAP sensors are rather expensive, but I guess he's using a more cost effective sensor.

All food for thought re the CBX, but is another reason for grafting the 800s injection onto the 750 as provided it can physically be done, then it's relatively simple as there's a ready made wiring harness with all the required sensors and just the one ECU module. No other ancillary electronics required. Well, apart from a Power Commander or equivalent. At least I assume it will need some tweaking, although just have to see on that once it's running.

Did you go to Patrik's NC30 Fuel Injection project blog (as was suggested on page 1 of this thread)?  If "simplification" is your overall aim it's important to realize there are different areas of a motorcycle fuel injection project that can present as very, very complex.  If you take the time to read Patrik's NC30 blog you'll see how complex it was for him to adapt throttle bodies to the bike.  He has skills and equipment that I will never have (CNC machining, for one example, and he's highly mathematical). 

So I choose to simplify by not attacking areas like the mechanical aspects of the throttle body (especially a throttle body assembly as complex as a Honda V4!), and instead I'm willing to suck up the punishment of lots and lots and lots of wiring and soldering.

11 minutes ago, BiKenG

I see, so there's a MAP sensor for each cylinder. I have a funny feeling Honda MAP sensors are rather expensive, but I guess he's using a more cost effective sensor.

Motorola MPX4115 MAP sensors are pretty cheap.  I always use the MPX4115 because it is their basic atmosphere model (as opposed to other MAP units designed to handle turbo or supercharger boosted engine MAP signals), they sense in a range from 115 kPa down to around 9 kPa.

2 hours ago, GreginDenver

Did you go to Patrik's NC30 Fuel Injection project blog (as was suggested on page 1 of this thread)?  If "simplification" is your overall aim it's important to realize there are different areas of a motorcycle fuel injection project that can present as very, very complex.  If you take the time to read Patrik's NC30 blog you'll see how complex it was for him to adapt throttle bodies to the bike.  He has skills and equipment that I will never have (CNC machining, for one example, and he's highly mathematical). 

So I choose to simplify by not attacking areas like the mechanical aspects of the throttle body (especially a throttle body assembly as complex as a Honda V4!), and instead I'm willing to suck up the punishment of lots and lots and lots of wiring and soldering.

Yes, I've read most of it, but a power cut here prevented me from finishing it. I will go back and read the rest though. It has encouraged me to start looking again at adding CNC capability to my mill. That would be enormously helpful in so many ways. But I digress...

I understand that modifying the TBs to suit won't be trivial, but Patrik and Durbahn both use the TBs from a totally different bike and then had to totally create their own maps etc. from scratch. I am currently of the opinion that using 5th Gen TBs will not actually be as difficult although I may change my mind once I start hacking them.  :biggrin:

However, if I can get the TBs to fit, the rest of the system is essentially off-the-shelf, just by using the 800 parts and it should even run like that with just minor tuning required with a PC. All that is a BIG advantage by using the VFR800 parts. I do have to add a Cam sensor, but that's been done before.

Of course the first requirement is that I can get the TBs to fit and I'm waiting on a set of 5th Gens I can start work on. Currently I'm firmly of the opinion that it will be easier than modifying the carbs, but I guess I'll soon be finding out if I'm right or wrong on that. It's all good clean fun though.

2 hours ago, GreginDenver

Motorola MPX4115 MAP sensors are pretty cheap.  I always use the MPX4115 because it is their basic atmosphere model (as opposed to other MAP units designed to handle turbo or supercharger boosted engine MAP signals), they sense in a range from 115 kPa down to around 9 kPa.

Good to know. Thanks for that. A typical Honda MAP sensor (I just checked for the RVT1000) is £256. So for the CBX, that would be prohibitive.

I also have a VTR1000F FireStorm (er, Super Hawk in the US?) that I'd like to inject. So another project to keep me busy. Possibly do that before the CBX. Just see how everything else pans out.

Late to the party but I'm considering adding EFI to my project RC24 VFR (which is planned to be a 840cc '88 FJ engine in an '86 FG frame). I have the '86 FG engine but the '88 FJ engine is a better starting point with the *one* exception of the '86 having a cam sensor already (but smaller valves, different cams etc etc). 

'86 has a cam sensor *but* the crank sensor is useless for EFI. It is merely a single tooth trigger.

'87+ RC24/RC36 has a 12-1 tooth wheel (11 teeth at 12 tooth spacing with one 'missing') but no cam sensor.

'98+ RC46 (and the RC45) has a 12 tooth wheel & a cam sensor. 

The '86 runs non-wasted spark, all the others run wasted spark but single cylinder wasted spark (not sure about the RC46, it's probably non-wasted as the ECU knows where it is in the cycle). Any aftermarket ECU needs to have 4 separate IGN outputs. 

It doesn't look possible to fit a '86 cam sensor into later RC24 let alone an RC36 as the castings are different, it appears to be a small VR sensor slightly to the left of the front intake cam and picks up off a single "tab" off the cam gear. Although you could I think fit something in the same place and add a sensor in the cam cover. In comparison it is trivial to add the later 12-1 toothed wheel to the '86 and it looks like you should be able to fit the 12-tooth wheel to the RC24 and RC36.

RC46 TB's are IMO more trouble than they're worth, the spacing is wrong, the angle is wrong and they're small. IMO you'd spend more time trying to adapt them than something else entirely. 

I'm not sure about the later RC36's etc but the 88/89 RC24 has 36mm carbs which are 44mm OD where they fit into the inlet rubbers. 

So I'm looking to use 2001-2 GSX-R600 TB's, these are only 2mm larger at 38mm ID and more importantly 44mm OD, ie the same as the original.  They split apart and the plan is to sacrifice a set of old carbs for the linkages and top plate. Then use those to work them into the original airbox. 

Fuel rails will need to be custom, I have seen  GSX-R1000K1/2 TB's which have a nice fuel rail that splits into multiple parts....but the TB's are too big and you'd need two sets to give enough "pieces" off the rails to work (and still need to fabricate additional lengths).

I have one issue at the moment in that I'm not sure if Microsquirt is enough for the VFR. It only has two injector outputs and the 180° crank means even with a cam sensor you couldn't do sequential injection as the second cylinder would always be at the wrong point of the cycle so it would be batch-injection only. To do things properly would need duel Microsquirts or an MS3.

Interesting about the multi-MAP though, I'll have to take a look at that. 

BiKenG, 12/8/2017 at 8:26 PM

I do have to add a Cam sensor, but that's been done before.

You don't need a cam sensor, you can have EFI without it but it limits you to wasted spark and either batch injection (ie random all cylinders squirt at once) or semi-sequential injection (one half squirt per cylinder every 360°, ie one squirt is correct, the other isn't) rather than fully sequential injection (ie one squirt per cylinder every 720°). 

Again note that the Microsquirt cannot do either semi or full sequential on the VFR750F or VFR800F (it could do semi-sequential on the VFR750R or RVF750R) as it does not have enough injector outputs. 

since fi has so few actual benefits over carbs, and since so many fi bikes are available now, it seems impossibly difficult and senseless to try a conversion.  anyone who can't get their carbs working and tuned to 100% of their potential hasn't got a chance with a complicated, computer- and sensor-driven fi system that was never designed for their bike.

This is a technical discussion rather than a justification of if it is at all advisable!

I'm largely in agreement...but

17 minutes ago, squirrelman

since fi has so few actual benefits over carbs

EFI has a massive number of advantages over Carbs. It is more efficient, gives better starting, better emissions, it adjusts to altitude and pressure differences better. It is massively easier to tune and does not suffer as badly from wear or from alcohol (eg e85). 

17 minutes ago, squirrelman

and since so many fi bikes are available now,

But none of the more modern bikes are substantially better. 32 years after the introduction of the VFR750F and and the very latest VFR800 manages to be 10Kg heavier with the same amount of power and while I've not ridden the RC79 the VTEC of the RC46 was horrible and the engine uninteresting. 

Objectively it is a better bike in every way. 

Subjectively...it's a poor relation to the earlier models. 

I have zero desire for one and so the argument that it isn't worth it because there are new FI models is a poor one. 

17 minutes ago, squirrelman

anyone who can't get their carbs working and tuned to 100% of their potential hasn't got a chance with a complicated, computer- and sensor-driven fi system that was never designed for their bike.

I'm 98% in agreement if we're talking about stock bikes. Where it makes a difference is when you have modified it, the ability to tune with a laptop rather than spend a fortune on jets/needles and hours taking it apart and putting it back together again (and I *hate* taking the carbs on and putting them back on again).  Still, even with modified bikes its more something to be done for it's own sake rather than because of any real advantage.  So again I'm largely in agreement. 

Fastdruid, I'm curious about your special note of E85.

Have you run such?

If so, I realize this is a carburetion discussion, but did you make any other optimization changes (higher compression/boost)?

VERY interesting topic (retrofitting FI to older VFR's) and I agree that it is probably the better way to go for those with increasingly complex modifications (E85).

Please, keep this thread going !

-Smack-

13 hours ago, Smack

Fastdruid, I'm curious about your special note of E85.

Have you run such?

If so, I realize this is a carburetion discussion, but did you make any other optimization changes (higher compression/boost)?

VERY interesting topic (retrofitting FI to older VFR's) and I agree that it is probably the better way to go for those with increasingly complex modifications (E85).

Ah no, not personally and I'm not intended to.  I mean in theory you could get something like 20% more torque on E85 (or potentially more, up to 40%) but you'd need to replace all the aluminium and rubber parts in the fuel system along with tuning to make the most of it....  

E5 / E10 is likely to be more realistic which has issues already on older carb bikes with "carb jelly" not to mention eating unobtainium rubber carb parts (seals you can replace and some are available in E5/E10 proof but diaphragms etc are NLA) and then you have the rusting tanks... (although that is still a problem with EFI). 

I'm "just" planning on a big bore (837cc) + EFI which should see about 120hp (based on others who have done the same) running on "normal" pump fuel. 

I have -by mistake- run my 4th gen on E85 and it ran

utter,

utter,

utter,

utter

SHYTE!!!  :goofy:

GSX-R600 throttle body on VFR750F (RC24) carb rubber. 

It is a perfect fit. No pissing about with different adaptors etc. Bodies split easily (with the loss of the secondary throttle valve) although its going to be a pain to forge the linkages. 

I know the RC36 carb rubbers have a different p/n and I don't know if the carbs are the same diameter there. 

[image: CY4Lcnxpy0fq77V1LS50rpzsBfCEvHUGgyieElaSvRqZ37ZaT7OqCjj_uOkFl-64-No4TYtlWbd-2QSw0YgB-KRdKE6gVs8w8oc6PYNFQUZ0npY7sBFip7ThVaCpFZ-YjWkyrGQwSlTWbqN56yQorlkZqRHUuKZBCfEXtkrgS-PSecSBOl3ZskGbw2G3dPx0rB7PMQdScy_Wmf7HZJiRnACsDGWx5CG2t__stNwkR5Glw-0fTL5cPvLSZUOtbZgp-0sXlTvQe670qBJp9YYs8JGRjtmoWY14UtOgRskMryOfyBdpdDO_TIS6ozojI0if_bJXlZdlTXi_1xqJUdL_clU-6G30gIMr4W4eHjN76r8xnrgPVTfMYIZhKk4JvXRhEftWAuMMOoy35ys5HD_6O2hME_Ku4iFv5gIUSbU9BFv9Y88v5IR85fnjW-paJ6bJg0pUlRxuQ7CdWHUzue-LQLQppI4ioKwj90V0tvEnvfpZ-eNiz33nuIw7v65aNfg2FMoYaJ_xQvgHqXLWkmrPk6CY4m-SJTZ9-U4HO0DagVxsoFHg4xW2P8gwPSjsntp_Ak7NQavccnXXB58QmvoXWuyfsBl_14Qfx4c1YuYoLlwCjWuBK6N2dhtVQyCr-UwjXspit4wSjmFQRu36nj5BW87lSQ=w1186-h889-no]

(I'd have put it on the spare engine but its cold outside and the old rubbers are rock solid, I utterly failed to get it on out there)

Hi guys, i thought i would add my 2 cents for what it is worth.  I am wondering if you have got any further with your efforts yet? Just to spurr you on I have done this project on a ZXR 900 engine currently in a 7R frame and i can say that yes it was worth all the blood sweat and tears! Yes there lots of head scratching moments but nothing that someone else has already done, so just google it! I have learned so much from that project that I am now currently gathering all the nessasary components to do the same to a vfr750 gen4. I will also be adding a zx10r front end for the usd forks and radial calipers also adding an RVF body kit for the RC45 look.  Iwill be using a microsquirt v3 ecu, triumph 675 throttle bodies and also going to a coil on plug system to save a little space. for what it is worth i think it will be hard work to adapt the vfr800 system/ecu to run with the 750. I am willing to share any info and help others where i can. It is good to find other people with a similar mind-set and the same "I want to do it just because i can". Dont loose heart cheers Nick.