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BiKenG

RC36.2 (4th Gen) Fuel Injection discussion

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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?

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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.

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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.

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7 hours ago, bykemike said:

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.

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

Or to quote Lorne "looking forward to your Odyssey"

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

20160705_091722x.thumb.jpg.b914a03fa19538b571168a7a135b0a41.jpg

 

Ciao,

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13 hours ago, bykemike said:

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.

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6 hours ago, Lorne said:

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.

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5 hours ago, JZH said:

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.

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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,

 

 

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1 hour ago, JZH said:

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.

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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.

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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.

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6 hours ago, The Phantom said:

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.

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8 hours ago, coupedupsubie said:

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?

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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.

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16 hours ago, Mohawk said:

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.

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

 
I'm pondering the possible fit of throttle bodies and intake rubbers. Have 800 TBs varied in size over the years? I know the injectors have changed a couple of times, but what about the intake sizes, have they altered at all?
 
Likewise, did the carb size change between the 3rd and the 4th Gen bikes?
 
I have some 800 TBs (late 5th Gen and a 6th Gen) and will soon have some 4th Gen intake rubbers to compare to. But I've no obvious way of knowing if there were any differences from the items I have, without buying one of everything of course.
 
I suspect all the 800 have the same size intakes and likewise the RC36 models, but can anyone confirm or refute this?

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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.

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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.

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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.

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

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

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?

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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,

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