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5th gen injectors upgrade?


Stray

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Hello All, 

 

Looking to pick the brains of those who know more than me about 5th gen VFR800 injectors - what can I upgrade my single-hole OEMs with? 
 

Got the whole bike torn down for a massive project and thought I’d upgrade injectors while there. Just because.
 

Nothing wrong with the stock 5th gen units but injector technology has improved since the early pioneering days of fuel injection. 
 

Here’s what I know and read about: 

1. 5th gen injectors are same as early Honda CRV cars and have a single hole

2. 6th gen have 12 holes and same as early CBR1k (I think?)

3. Mohawk is running early Fireblade injectors (4 hole?) on his 5th gen (would love to know more about this, mate!) 

4. Someone in this forum is running CBR1k injectors on their 5th gen

5. Rangerscott fitted 6th gen throttle bodies to his 5th gen and reports better MPG

7. MPG has improved quite a lot from 5-6-8th gen
8. Some early Honda CRV guys are running Blackbird injectors in their built cars but having to boost pressure (read about this a long time ago...)
 

I’d love to be told there’s “X” injector with 12 holes that slots right into the 5th gen throttle bodies but doubt it’s that simple. What would you do in my shoes if you had the bike apart and the time to mess about with this? 

 

Would love to be able to use 8th gen (or 6th gen) units but don’t know what needs modifying to fit. Don’t mind hackzing at things to make them work. 
 

Open to all options and opinions. I could just leave it alone but kind of set on upgrading. 
 

Best, 

 

Stray

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11 hours ago, Stray said:

Hello All, 

 

Looking to pick the brains of those who know more than me about 5th gen VFR800 injectors - what can I upgrade my single-hole OEMs with? 
 

Got the whole bike torn down for a massive project and thought I’d upgrade injectors while there. Just because.
 

Nothing wrong with the stock 5th gen units but injector technology has improved since the early pioneering days of fuel injection. 
 

Here’s what I know and read about: 

1. 5th gen injectors are same as early Honda CRV cars and have a single hole

2. 6th gen have 12 holes and same as early CBR1k (I think?)

3. Mohawk is running early Fireblade injectors (4 hole?) on his 5th gen (would love to know more about this, mate!) 

4. Someone in this forum is running CBR1k injectors on their 5th gen

5. Rangerscott fitted 6th gen throttle bodies to his 5th gen and reports better MPG

7. MPG has improved quite a lot from 5-6-8th gen
8. Some early Honda CRV guys are running Blackbird injectors in their built cars but having to boost pressure (read about this a long time ago...)
 

I’d love to be told there’s “X” injector with 12 holes that slots right into the 5th gen throttle bodies but doubt it’s that simple. What would you do in my shoes if you had the bike apart and the time to mess about with this? 

 

Would love to be able to use 8th gen (or 6th gen) units but don’t know what needs modifying to fit. Don’t mind hackzing at things to make them work. 
 

Open to all options and opinions. I could just leave it alone but kind of set on upgrading. 
 

Best, 

 

Stray

+1:lurk:

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Oh, and I forgot to say the Honda S2000 guys are using the Blackbird injectors for their built car engines. 
 

Aaaaand, it turns out the Hyabusa injectors are exactly the same size and are also being used in built S2000 cars.
 

Blackbird and Hyabusa injectors are apparently the same size but flow differently (I don’t know the numbers). 
 

Soooo, if Blackbird injectors fit the VFR then so do Hyabusa. 
 

Come on folks - give us some info! 

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So I did a load of digging into this when I did mine. 4 hole from many car tests are much better than single hole, but 12 hole is more the norm, but the step up is not the same as 1-4 when compared with 4-12 but 1-12 is better. Some newer injectors are 16 hole. 
 

CBR600F4 & CBR929 injectors are the same 4 hole units with the same connector as 5th gen, just use the 5th gen mounting washers & remove the plastic orientation stub, which 5th gen does not have. But are designed for higher pressure. I tried with VFR regulator & had to add loads of fuel. I then tried 4bar, but was to much. So switched to 3bar & its great. I run 14.2 AFR on my RBR + MTB, runs clean, better MPG & no over heating even in silly 33c temps. 
 

The early Hayabusa used the same injectors as the 5th gen. You can buy fairly expensive Hayabusa aftermarket units, 12-16 hole.

 

The simplest upgrade is a 6th gen throttle body, plus airbox, bottom half will do, as tops are the same. Just switch the TB harness at the large multi block that you tap for PC3/V or RBR etc. I can't guarantee the pinout is the same so consult a wiring diagram first.  2014+ 8th model looks the same as 6th gen, but I've never compared them in the flesh. YMMV

 

A few people on here with 6th gens with 5th engines installed have reported better mpg with PC or RBR installed. 
 

The one advantage of the single hole pintle injector is that its effectively self cleaning & very hard to gum up. The tiny multi hole units are much easier to block. 
 

Hope that helps. 

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A consideration for a 98/99 converted to a 6th gen TB would be that you lose the manual control for the starter valves and would likely convert to using the 6G wax unit.  Since the 98/99's don't have that, the thermostat housing and clutch side waterneck on the rear head need to be swapped for 2000 to 2009 units which have the nipple for the small hose that goes to/from the wax unit.  Last time I looked at the parts fiche both were available from mother Honda. 
 

If someone were very good at modding, it might be possible to hook the 98/99 cable control to the 6G starter valves, but it would probably require some fabrication of some small parts.  I looked at that but determined I do not have the abilities to pull that off.  Wish I did - I'd love to be able to get rid of the wax unit on my G6. 

 

 

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Mohawk, I’m very glad you chimed in with all that info. Advice from you is well thought-through, deeply researched and proven/first hand. I’m in your debt! 
 

Cogswell, thanks for the info on starter valves. I love the choke lever on my ‘98 and loads of people on here hate their wax units. 
 

So I think I’ll take Mohawk’s info and throw some CBR 4-hole units in to avoid the hassle of switching to wax units and such. There’s a good enough gain from 4 holes to keep me happy. 
 

Got ‘98 and ‘00 (with wax unit) throttle bodies on the bench. Also got 5th & 6th gen air boxes. Have been messing about with trumpet lengths and configurations recently following Mohawk’s work from a few years ago so it’s been fun. 
 

Air boxes are so oily on VFRs...

 

Many thanks for you help, chaps! 

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Anybody do the fast idle lever mod conversion on a wax unit bike? I find the lever very useful in a lot of situations....on and off the bike....

Just a curiosity....

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Same here.  IMHO the wax unit was a solution in search of a problem.  The lever actuation was much simpler and IMO works better and is more reliable.  Probably some sort of EPA reg . . .

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2 hours ago, Cogswell said:

Same here.  IMHO the wax unit was a solution in search of a problem.  The lever actuation was much simpler and IMO works better and is more reliable.  Probably some sort of EPA reg . . .

The wax units are ubiquitous across lots of early FI Hondas, I know the ST1300 and SilverWing scooter use the same set-up, and have the same issues with blockages to the coolant passages from time to time. Not sure how else you can provide an auto cold fast idle system prior to the introduction of RBW throttles that allow the computer to drive the fast idle sequence. 

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The fast-idle wax unit was introduced on the Y2k model in conjunction with several other changes Honda made to the engine to make it more efficient and reduce emissions.  It wasn't done to simply automate the idle-adjustment process.  (FYI, Honda had introduced the "HECS3" version of the 5th gen in certain markets in Europe in '98, where it was sold as an alternative to the regular version (but with an 8PS loss in power).  From the 2000 model year on, they only sold one version.)

 

Here's the bit from the Y2k Press Info:


 

Quote

 

Engine
In order to provide the power and performance required to allow the HECS3 low-emissions system to be included standard on every version—or the only version—of the VFR to be released in the year 2000 and onward, the VFR’s design team restudied the effects of the PGM-FI fuel injection system on catalyser efficiency and its related emissions output. Since all factors in the system are closely interrelated in a critical balance of performance, any changes made to one aspect can have major repercussions elsewhere that may not be so easily compensated for.

 

The pivotal key to the difference in the performance of the VFR’s ‘standard’ and HECS3 configurations could be found in the design of the exhaust system, particularly in the vicinity of the catalysers themselves. To work at optimal efficiency, the catalysers must reach a certain temperature threshold that permits their catalytic elements to function properly. This is especially important at start-ups, and can be a problem in very cold weather conditions, since the catalysers are positioned relatively far away from the engine and therefore take longer to reach their optimal operating temperature.

 

The exhaust system for the current HECS3 system overcomes this problem by using narrower tubing to help accelerate this pre-heating process. This may be a competent fix, but the smaller tubing has the additional effect of restricting maximum power output somewhat, so the HECS3 version of the VFR ended up being approximately 8PS down in maximum power compared to the standard version. While not a major drop in power, and certainly better than any catalyser system developed until now, this was not what the VFR’s design team was hoping to achieve. The solution to this problem came in the form of a new development made for the CBR1100XX Super Blackbird’s fuel injection system.

 

New Automatic Bypass Starter

 

Extremely cold temperatures can often cause oil to thicken, mechanical friction to increase and injected fuel vapour to condense along inside walls of carburettors or fuel injector bodies. These symptoms often combine to impede cold weather starting, and make initial warm-up operation extremely rough and irregular, with frequent stalls and fitful performance until the engine reaches its optimal operating temperature.

 

To effectively combat this problem, the VFR’s advanced fuel injection system now features the addition of a new automatic bypass starter system that ensures smooth performance and quick starts in virtually all weather conditions. Introduced last year on the CBR1100XX Super Blackbird, this new automatic bypass starter opens new internal air passages designed into each throttle body to deliver an extra shot of air that assists starting and increases idling speeds for quicker warm-up whenever coolant temperatures fall below 40° C. As the engine warms up, coolant circulates through the throttle bodies to warm the fuel for optimal combustion, and through the bypass starter to actuate a small piston that gradually pushes out to close the auxiliary air passages. Completely automatic, this innovative and effective system ensures quick and simple starts, shorter warm-up cycles, steadier idling and smoother performance in all operating conditions.

 

 

Ciao,

 

JZH

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I just found the wax unit on my Y2K model was fine if allowed to warm up before riding, but if I set off with it on, it would get too hot to soon & disengage, then when you slowed for a junction the bike would die as still to cold and fast idle was already off. Much better now with manual fast idle lever, wait until display says 60C then turn it off 👍

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On 2/14/2022 at 4:26 AM, mello dude said:

Anybody do the fast idle lever mod conversion on a wax unit bike? I find the lever very useful in a lot of situations....on and off the bike....

Just a curiosity....

What are those advantages? Could you explain that to me?

 

I own a 2000, with the wax idler and have only once had the engine die on me after starting (when still cold and it was around 0 degrees C outside). I think that my startervalve sync has helped with preventing this from happening more often. based on logic, not facts 😛

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12 hours ago, ariesblade said:

What are those advantages? Could you explain that to me?

 

I own a 2000, with the wax idler and have only once had the engine die on me after starting (when still cold and it was around 0 degrees C outside). I think that my startervalve sync has helped with preventing this from happening more often. based on logic, not facts 😛

 

One use I've found for it is when riding through mountainous areas.  The ECU does not have an idle air bypass that was common for the era and it thus cannot compensate for changes in atmospheric pressure.  The most pronounced I ever had was at the Pike's Peak summit.  My G6 would just not idle - it could maybe maintain around 700 rpm, so I had to constantly hold the throttle to keep it running.  Once back to lower levels it regained its idle.  Even at 5,000 feet which can be common in the western US, I find myself pulling out a screwdriver to change the idle speed.  Then once back to near sea level do it again since its idling too fast.  The manual lever lets you keep the idle more or less where you want it if idle is baselined near sea level. 

 

The other for me is that the wax unit is such a PITA to get at that taking that out of the equation is one fewer potential service project I might need to do. And I think it's happening on my G6 - there doesn't seem to be a fast idle these days - it stumbles along until it warms up then idles fine.    Just my $.02. 

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9 hours ago, Cogswell said:

 

One use I've found for it is when riding through mountainous areas.

 

The other for me is that the wax unit is such a PITA to get at that taking that out of the equation is one fewer potential service project I might need to do. And I think it's happening on my G6 - there doesn't seem to be a fast idle these days - it stumbles along until it warms up then idles fine.    Just my $.02. 

 

Okay thats interesting, Last summer, riding through the alps i didnt notice much difference in idle speed and power delivery. We're talking elevation changes from 200 meters to +1500-2200m (650ft - 6500ft in freedom units :laughing6-hehe:). granted i wasnt pushing hard (unknown roads and not wanting to spoil a fan.fucking.tastic vacation)

But I can get the use-case for the lever. Good to know.

 

I luckily havent had to touch the wax unit. Lets pray to the Viffer gods i dont have to 😉

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23 hours ago, Cogswell said:

at the Pike's Peak summit.  My G6 would just not idle - it could maybe maintain around 700 rpm, so I had to constantly hold the throttle to keep it running.

 

I've never noticed any issues at elevation with my '09 6th gen, even atop 14,110 ft / 4300 m Pikes Peak, or any of the many 10,000 ft passes over the years. Funny that two modern VFRs behave so differently. Here's my VFR at a piddly 12,095 ft / 3686 m 😉

(fingers' crossed that I'll be able to travel this summer)

atop Independance Pass.JPG

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My 2002 has no problems with altitude.  It is a little reluctant to restart at 5,000 feet but I blame dirty injectors.  It also sometimes needs a little throttle to start when cold.

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Following this thread with interest as I currently have the throttle body off my '98 5th gen to facilitate general clean up and other things I'm doing. I was planning to have the injectors professionally cleaned while it's out but am always interested in upgrades. Interesting to note that the CBR929 injectors are NLA from Honda, but the F4 are still available  and are about half the price of 5th gen, which are also still available. I have no interest in swapping throttle bodies but am curious about installing the CBR600F4i injectors into the 5th gen unit. The only engine performance mod happening this winter is installing the VFRD header. I didn't plan to install a PC/Rapid Bike right away, maybe next winter.

Question for Mohawk, did you use a different OEM fuel regulator or an adjustable aftermarket unit, and do you think there is any point to this upgrade without doing the PC/RBR at the same time?

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Quick update: 

 

- 929 injectors are a drop in (thanks Mohawk)

- 954 injectors fit in 929 throttle bodies but wiring is all wrong

 

Verdict = 929 injectors for the win! 

 

 

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On 2/21/2022 at 7:52 PM, Stray said:

Quick update: 

 

- 929 injectors are a drop in (thanks Mohawk)

- 954 injectors fit in 929 throttle bodies but wiring is all wrong

 

Verdict = 929 injectors for the win! 

 

 

Stray,

    Is there any chance you have a part number for those 929 injectors? I would imagine they're either Bosch or Denso? Did you alter the fuel pressure regulator or map settings on your bike or did you just do a direct swap and leave the OEM settings as is?

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Sorry Mike, I haven’t got that far yet. Still battling with subframes and bodywork. The injection system will be the last bit to get done. 
 

Still have electrics, new coolant system, suspension upgrades...and so on. 
 

Mightbe a while before I post an update but certainly will when the time comes. 

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You will need to increase the fuel rail pressure for any injectors other than stock. VFR800FI runs 2.5bar Pressure, anything newer runs 3 or 4 bar pressures. 929 is 3bar. I ran mine originally on 2.5bar but had to add loads of fuel using my RBR module. I tried 4bar but even on zero map it delivered way to much fuel. So switched to 3bar & its been great with better mpg to boot. 
 

One of the benefits of multi-hole injectors is that they produce finer fuel droplets which means better fuel air mix, which allows less fuel to be injected because it burns more completely. Hence the evolution from single pintle through 4-hole to 12, now 16-hole injectors. The greater the hole count, the smaller the holes the finer the fuel mist produced. Smaller holes require more pressure to deliver similar volumes of fuel in the same time frame.

 

The stock pintle injector shoots the fuel out in a cone shape & relies on deflection off the intake walls to complete atomisation of the fuel. The 4-hole produces a V shaped finer spray directly into the inlet track either side of the intake bridge between the intake valves. This avoids wasted fuel being sprayed on to the bridge & sticking to the intake walls. 
 

There are many car videos on U-tube showing good gains from 4-hole compared to 1-hole. 
either way if you swap out the injectors you will need to correct the AFR with a combination of PC/RBR &/or fuel pressure regulator. 
 

There will be a market for an adaptor to use standard automotive FPR's as VFR ones are NLA & are not a standard fit. I had to make mine form a couple of adaptors. 

1998 throttle bodies before

39DB4FD8-6455-4AE3-B963-E7B71EDD70EF.thumb.jpeg.e15cd2ee3a5c91625f136c5bce3cb7f8.jpeg

 

And after

D537E7DC-1D01-4D10-93F3-688A22E00587.thumb.jpeg.a669c55e5602d160d0b5ddfdd277119f.jpeg
 

I had to use the 90 degree to drop it below the airbox. There is only just enough room for this. 

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Some should sell kits for monkeys like me...

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Its one of the things I want to do once I retire. Just to keep my hands busy. Oil Cooler+line kit, FPR kit. +/- Injectors etc.

 

Unfortunately I'm in the UK so, shipping would be a killer, for US guys, which is mostly where the market would be. 
 

But we really could do with a VFR store listing all the custom options we can get & who from. 

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