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magellan

DIY Fuel Pressure Regulator Mod

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Anyway, my red herring / blue cod about the Superstorm's lunchbox missed the obvious point, that you made mention of: it's carbed, and tidy, well-organised airflow is more important to it functioning well than our injected beasties.

I'm with you on all that, although I might have missed the detailed point about that particular bike vs. ours. Wot I DO know a little about is the huge amounts of freakish science and hodgpodge experimental tweaks that are made on race cars, particulary those with a big fat carb sitting right underneath a monster hoodscoop, in a variety of attempts to right a wrong or improve a marginal right. Before 1970, hood scoops were taken directly off the hood surface, naturally, right? Just like always. Then one day, the big meanie Chrysler unleashed their factory designed and built Pro Stock Barracuda (known as the Mopar Missle) on the racing world. Sitting on the hood was this obscenly tall hood scoop, with a snorkel on that hood scoop, such that the inlet poked its nose into non-boundary layer, non-turbulent air. Inside were slats and eggcrates and other flighty stuff, all to properly jam air down the eight huge carbs throats....without upsetting the bleeds and vents and other bits that make the carb meter properly. Never been done before. Very high-tech. Worked, too. Within a month, every car out there had some bulbous nose in it's hood.....but the science was beyond the normal racer. And now? Nearly every form of auto racing (including F1) has their air coming in through a tall snorkley convenance. But remember...all WOT, no noise, no emissions, no mileage requirements! Anyway, thank you, Chrysler.

BTW: would it have been easier to have some connector pipe thingos (technical term) made than gutting the cat? Or did you want it to look standard?

I tried, but 1) it just doesn't work like that due to geometry, 2) didn't want to ruin the alignment of the outlet to the muffler, in spite of plans for jigs and such, and 3)....yeah, Big Number Three.....I recognized the point of diminishing returns, I think. Getting the cat out of the bag will be a significant reduction in back-pressure, I have determined. So.....cut the bottom off, wrestled the cat-guts out, rewelded the bottom back on, sent to Jet Hot....awaiting return. We'll see. Could be crap!

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Wow, I leave for a few hours and the whole thread goes ballistic! Awesome advice and thoughts from everyone.

As far as fuel injected engines, 'Helmholtz resonance (http://www.phys.unsw.edu.au/~jw/Helmholtz.html) and other esoteric physics to maximise cylinder filling' do come into play, though not nearly as much as with carbureted systems (for the reasons mentioned earlier in the thread). Engineers know that big pressure pulses and areas of low pressure at the mouth of a specific throttle body or intake runner will create an imbalance in air/fuel ratios between cylinders. Generally, these imbalances are quite effectively engineered out before the product goes to market and gets all screwed up by us in our silly quest for more power.

Tuning aficionados (aka 'nutcases' :beer: ) go to great lengths such as extrude-honing intake runners and polishing ports to reduce unwanted turbulence or restriction [the thermo-plastic intake plenum on Trace's Vette does a hell of a job delivering air equally, smoothly, and abundantly to the intake valves, where precisely metered fuel is injected by the ecm based on inputs from the mass airflow meter (MAFS), coolant temp sensor (CTS), intake air temperature sensor (IATS), throttle position sensor (TPS), and oxygen sensors (O2S)].

As mentioned, the VFR's EFI is primitive in comparison. I suspect Honda wanted to avoid going directly from carburetion to a system as complex and "sensor-intensive" as the Vette's while still addressing stiffer international emissions regs.

So where does that leave us? We could all pull our airbox lids off and do timed runs as Trace suggests (a great start), we could make repeated trips to the dyno after every little mod ($$$), or we could weld bungs into each exhaust pipe in the header and install wideband O2 sensors from Dynojet or Innovate and really get hard facts.

Doing the latter would allow me to see whether a specific cylinder is richer or leaner than its mates and would indicate whether a particular injector was less efficient than the others or airflow into a velocity stack has been hindered by my fiddling. By doing so I make myself significantly smarter about what my bike is doing than the ecm or even a Power Commander can be. I can then make mechanical changes or adjustments to the fuel map and tune my bike to the Nth degree.

The problem, and it's a doozer, is that at this level of analysis, my bike will be revealed to be quite different from any of yours, so one-size-fits-all mod advice no longer works.

Much depends on personal expertise and how much we individually want to spend, and unless we're each going to take a turn optimizing everything on our own bike, we have nothing better to rely on than anecdotal modification suggestions (scary) or our own instincts (as Chumly says, "I would probably not be able to know for sure if I was making overall air flow parameters better, but I would probably notice when I made them worse!"). With things like pulling off the top of an airbox, it's a good idea to be fully prepared to buy a replacement for the part we just mangled. Keep in mind too that it is certainly possible to exceed persional expertise and do permanent damage in the quest to "make a VFR into a 'Busa".

Nevertheless, it's a hell of a lot of fun to try!

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magellan,

That'll teach ya to leave!! :P

Yep, I fully agree with your "roundup" assement. You've bracketed the issues quite well. Mebbe we should just go RIDE the suckers and quit hacking our airboxes and gutting the poor, meowning cats! Nope...sorry....dying to see what the results of my torching and JetHot-ting the stock system will bring!! :beer: I'm thinking lots of PC tweaks are in my future. Glad I live in warm Florida so I can ride and tinker all "winter".

Hey...wait....who you calling a nutcase? I resemble that remark!

[And as for my Vette....after modding my 2000's "basic 350 hp" engine, I chose to do NOTHING to the 405 hp Z06 mill. No air mods, no exhaust mods (like I'm gonna remove the titanium exhaust and put SS on it!), no nothing....except a shifter, as the stocker is crap. I'd weld the hood shut if it wasn't made of fiberglass!! Point is, it's gangbusters right from the get-go...why ruin a good thing? I got it to go an 11.70, bone stock. Fergitaboutit! Don't want to be a nutcase about that car! Wash it--Drive it.]

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A couple of points that have (or not) been touched on, that I think are good:

First off, why are we modding these bikes? Certainly, there are better starting points if maximum performance is really the objective. The VFR will always be heavy and underpowered compared to the latest race-reps. (Remember, we could have paid less for a lighter, more powerful bike to begin with.) I would say the goals are to reduce or eliminate the flaws that we're all aware of (surging due to lean tuning, abrupt VTEC transition), and to improve the aesthetic experience, either sound level/quality, or visual. I can certainly see the value in FPR mods and PCIII's in order to optimize the tuning of the bike, but lets not fool ourselves about airbox mods and pipes, those mostly just make the bike look and/or sound "cooler", or are because we like to fiddle. Hell, I just spent about 10 hours polishing my rims; it looks boss and probably gives almost as much performance improvement (reduced rotational inertia, dontchaknow) as an aftermarket pipe.

How about timing? It's well known that ignition advance can have a significant impact on midrange, especially since these bikes are tuned for cheap gas. As long as we're prepared to run premium, I believe we really could see some useful gains here, and possibly even smooth out the VTEC with a shift in the timing at 7k. What would it take to start experimenting with that?

And what about disabling the VTEC altogether? What if you just left those pins in after adjusting the valves (probably not a good idea)? Assuming that the two-valve operation is primarily for emmissions (it's been shown that it's not for power or efficiency, compared to 5th gen.), why aren't we looking at solid buckets?

Then again, we could be happy knowing that we've got a relatively sophisticated bike that's green, comfortable, and actually performs pretty well (once you take care of the surging). I think I'm going to try to keep that in mind, and try to just focus on the rider mods by saving up for some track days and schools, along with good rubber and a bit of suspension tuning.

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fallzboater,

Right you are, beyond trying to reduce the quirks of the VTEC & EFI, I am not doing anything. 'Tis fun for me to chat/learn about all the other stuff though.

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And what about disabling the VTEC altogether?  What if you just left those pins in after adjusting the valves (probably not a good idea)?  Assuming that the two-valve operation is primarily for emmissions (it's been shown that it's not for power or efficiency, compared to 5th gen.), why aren't we looking at solid buckets?

I would like to know if the Non-Vtec valve buckets would fit where the Vtec buckets are.

If they are dimensionally identical, perhaps it would be possible to install 8 of them and permanently disable the Vtec that way.

.....or just find another new 2001 in the crate somewhere for $6700 and buy it.

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Flapper valve:

This is what Honda says in the Gen 5 Workshop Manual under Technical Features page 21-25. They call it the variable Air Intake System:

'OUTLINE

The intake area and the intake duct length are changed according to the engine revolution speed by opening/closing the variable intake duct, thereby contributing to upgrade the engine output.

From low speeds to medium speeds the intake is controlled by closing the variable intake duct to reduce the intake area thereby realizing high efficiency intake through upgraded inertial effect and pulsation effect of the intake air, and contributing to upgrade the low- and medium-speed output.

From medium speeds to high speeds the intake duct is opened to supply large volume of air to the engine, thereby contributing to the high revolution speed and power output of the engine.'

Next page shows the schematic of the components and explains that below the threshold rpm the flapper is closed, above it it is open.

It is generally believed on this forum that it is simply a noise abatement device. I am under the impression that it is thought that the flapper only closes at the noise measurement rpm range & that it is open below that - different to what Honda say (am I right?). I have removed the flapper & the snorkel but have not got the bike back on the road. I expect to replace the snorkel once I have tried it but possibly cut the inside away.

Honda's reference to 'upgraded inertial effect and pulsation effect' is Hermholz. The snorkel is thus the Heremholz duct as that is what is in operation at low speed when the flapper is closed. That would slightly raise the airbox pressure over a very resticted rpm range as Hermholz is to do with wave lengths matching duct lengths.

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Flapper valve:

This is what Honda says in the Gen 5 Workshop Manual under Technical Features page 21-25.  They call it the variable Air Intake System:

'OUTLINE

From low speeds to medium speeds the intake is controlled by closing the variable intake duct to reduce the intake area thereby realizing high efficiency intake through upgraded inertial effect and pulsation effect of the intake air, and contributing to upgrade the low- and medium-speed output.

From medium speeds to high speeds the intake duct is opened to supply large volume of air to the engine, thereby contributing to the high revolution speed and power output of the engine.'

It is generally believed on this forum that it is simply a noise abatement device.

Although I understand and appreciate this info, I still have to consider several possibilities. First, Honda may have been tuning for Helmholtz resonance that exists because of the existence of the airbox in the first place or the use of the snorkel, or a common and universal result of low-to-medium-speed sudden large throttle openings, or... who knows? Whatever their reasons were, we surely bugger up whatever airflow characteristics they were accounting for when they designed the flapper.

Whether that really messes up driveability or power output is easily determined at the dyno (or by our sweetly tuned metric pant seats :D ). This thread:(http://www.vfrdiscussion.com/forum/index.php?showtopic=16299&hl=dyno) shows that pulling the snorkel does little to change horsepower but makes intake noises most of us like, and I'd bet that before-and-after dyno runs for de-flappering would also show very small variations.

So, if it really makes little difference, do what you like. On the other hand, what if I fiddle with the airbox and get 5 more HP above 7000 rpm but lose 5 between 4-6000? Would it be worthwhile? Depends on me and what I want from the bike. If in doubt, I should just spend my time and money tuning the nut that twists the throttle or 'tuning for what I know' as Trace puts it.

Since I'm a mechanic and seem to just love writing windy posts, I'll probably tweak and tune like a madman and do exhaust gas analysis at each pipe until I've got it tuned to (subjective) perfection. And that's the day I'll get broadsided by a bus... :beer:

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Since I'm a mechanic and seem to just love writing windy posts, I'll probably tweak and tune like a madman and do exhaust gas analysis at each pipe until I've got it tuned to (subjective) perfection. And that's the day I'll get broadsided by a bus... :mellow:

Welp...we certainly hope not :thumbsup:

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Guest NunAddict
I've read about syncing the starter valves with the 20mm difference on the Brit web site, but somewhere I also recently read that the VTEC manual misprint claim is not true and the valves should in fact be set equal to #4. Still, I suppose it wouldn't hurt to give it a try and see if it makes a difference.
The 20mm difference turned out to be not the case, this is confirmed by Wiz et al, if you read the whole thread.

Can someone put in a link for the British website?

Thanks!

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Guest dirtyfur

Inspired by this topic (and with a recovered thumb after I attacked it with a hacksaw last week) I decided there was no better way to use a Sunday afternoon to embark on my own version of Magellan's Official FPR Recalibration Project. First though, it seemed only proper to give my K&N a clean on the way past. I haven't done this for about 3 years and 30K miles due to a seized and stripped screw at the front left of the airbox, just beneath those @£$%*" linked brake lines. So, first step, snap the corner off the airbox lid. I know, I'm a philistine, but I just couldn't be arsed to drill the screw out, particularly so close to a brake line. Next, scrape about half a ton of grit out of the filter, wash, rinse and repeat. Oh, and oil. I gather that's quite important.

Finally, I arrive at the FPR. I didn't happen to have the recommended 3/8 - 1/2 inch bearing handy, but it occurred to me that that's exactly how big the ball in a paint aerosol sounds when you shake it... 30 seconds of hacksawing later (I was careful this time - all digits accounted for!) I had the thing out of an old empty one. It's made of glass, but some vigorous squeazing with pliers in a controlled environment ("rag") proved it was tough enough. Not only that, but it's a smidge under 1/2 an inch. Perfect. After losing it in the V of the engine a couple of times I managed to get it wedged in the side of the FPR with an 11mm ring spanner behind it, using a plastic screwdriver handle as a fulcrum. Wearing the only eye protection I could find - a pair of oakley's - in case the glass exploded, I put as much pressure on as I felt comfortable with; enough to flex the spanner and, more worryingly, the frame! To no avail. The ball didn't appear to move relative to the FPR at all. I could only think that either my FPR is made out of extra-strong British steel (unlikely given the putty/compost alloy used for the factory exhaust system), or the ball was a touch big for the internal shoulders of the FPR. I should mention that I know nothing of the "internal shoulders of the FPR", so this is pure speculation. So, I tried a few other bobbley bits I could find lying around my garage: fixings from desks, random bolt heads, an M10 nut in various positions, and finally a bicycle ball bearing cupped in a desk fixing blue-takked to a screwdriver. Without wishing to kill magellan's idea (which seemed like a good one) I felt I'd tried everything I could, short of extreme force and a damaged fuel rail and/or frame. I considered taking the fuel rail off and using the Patented Vice and Mallet Approach, but was again thwarted by Phillips screws I couldn't get undone, this time on the intake funnels. So I gave up on my Official FPR Recalibration, at least for the time being.

All was not lost though. Following some careless handling of the airbox lid I was left with this random assortment of left-over parts:

gallery_12130_3368_914237.jpg

Flap, Snorkel & Servo

I didn't think they looked that important, so I thought I'd leave them off. There was a spare hose coming from cylinder 4's intake manifold which, in the original scientific ethos of the topic, I terminated with an old inlet funnel fixing bolt and some electrical insulating tape:

gallery_12130_3368_151074.jpg

Variable air intake servo hose terminator

I located the hose where it lay naturally around the front of the airbox.

The final result was one already posted by several punters, that of the airbox free of obstruction:

gallery_12130_3368_280198.jpg

Airbox modified

So that was that, really. I slapped all the cosmetics back on (um.. maybe I shouldn't include the tank as a "cosmetic"...) and got ready to take it for a blast.

Initial impression was that idle was lumpier than before. I needed a touch more throttle advance: normally I wouldn't use it for more than maybe 10 seconds, but now it needed a few minutes before the engine ran without struggling. Yet more seat-of-pants evaluation, but I was struck that the exhaust smelt richer than usual - maybe I have raised my fuel pressure after all. Could be just the clean filter though. Once the engine was warm, the lumpiness at idle evened out and took on the sound of an engine that just wasn't tuned to run at those revs.

Ok, must get to the point - does it ride??!?! YES! The engine sounds disconcertingly erratic at low revs (< 3,000), but pickup is actually unexpectedly torguey and responsive. There's a new low-frequency harmonic added to the song of Micron end-can and gear-driven cams which is particularly noticeable when drawing up to junctions, as the revs fall. It sounds awesome! Finally reaching the open roads, these modifications really came into their own. Acceleration is noticeably more intense. I'm afraid I can't remember who said it earlier in the thread, but 6th gear feels like 5th. So much so that the first couple of times I shift up through the box I was convinced there was another gear to go. On a flat road with no wind, the bike pulled hard all the way to 30mph short of one quarter of the speed of sound (indicated). The first time I was caught out by the savage power and backed off early. Next time I was prepared, but still impressed.

Front-end lift: lots of! 1st is... peaky. Just smoothly winding the throttle open would loop it if I didn't back off. When cogging up to 2nd, the front wheel briefly touched the road before coming straight back up again... just the sort of thing an idiot reaching mid-life crisis age needs smile.gif

All in all, not bad for a 10 year old bike.

Oh and by the way, yellow is the fastest colour!

Edited by dirtyfur

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I put as much pressure on as I felt comfortable with; enough to flex the spanner and, more worryingly, the frame! To no avail. The ball didn't appear to move relative to the FPR at all.

Yeah, I found this too.

The frame is scarily thin and flexy, unlike the FPR, which seems to be made to military specs. <_<

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Hi all, just registered as a newbie,to see if there was anything on eliminating the "snatchy" pick up from off throttle to on throttle at low speeds. Have to say other than that, the Viffer seems fine on speed in all gears I haven't felt the flat spots or lack of performance mentioned by others.

The biggest issue I have is the lack of a smoth pick up when just cracking the throttle open in low gears at slow speads, e.g. try picking up a small amount of power whilst going round a roundabout without a sudden surge,just can't be done.

Any ideas? :huh:

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DUSTY THREAD ALERT!

Hi Curt, welcome to VFRd.

The snatchy throttle can be helped by removing as much slack from your throttle cables as possible, without of course, inducing unwanted RPM increases with the bike idling, and swinging the handlebars from full lock right to full lock left.

Also, making sure your chain is not too loose in it's adjustment.

Lastly, check the rubbers in the cush drive in the rear hub and see if they are appreciably worn.

Those are the three free/cheap things to look into.

Another "trick" I've developed to deal with F.I bikes is that when I'm in first gear and maneuvering slowly, like in a parking lot for example @ ~5 mph, and I wish to accelerate, instead of just picking up the throttle, I pull in the clutch and slide it out again, whilst throttling up. It takes 100% of the snatch out of the situation.

Beyond that, you might look into the Fuel pressure regulator mod, or just buy one from Turbo City. I remember it helped immensely on my 5th gen with the throttle response.

http://www.turbocity.com/default.php?cPath=64

lastly, o2 eliminators and perhaps a Power Commander with a custom map. Definetly not cheap, but you can fix most anything if you've got a good tech on the dyno to make you a map.

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Thanks Rob, I appreciate your reply,

I'll get all that done ASAP. I tend to think it's also a function of "basic" fuel injection system vs carby's?

It's really the only thing I can fault the VFR on. I actually sold a Ducati ST4S & moved on (up) to the VFR, best move I've made in a while!

Cheers

Curt

DUSTY THREAD ALERT!

Hi Curt, welcome to VFRd.

The snatchy throttle can be helped by removing as much slack from your throttle cables as possible, without of course, inducing unwanted RPM increases with the bike idling, and swinging the handlebars from full lock right to full lock left.

Also, making sure your chain is not too loose in it's adjustment.

Lastly, check the rubbers in the cush drive in the rear hub and see if they are appreciably worn.

Those are the three free/cheap things to look into.

Another "trick" I've developed to deal with F.I bikes is that when I'm in first gear and maneuvering slowly, like in a parking lot for example @ ~5 mph, and I wish to accelerate, instead of just picking up the throttle, I pull in the clutch and slide it out again, whilst throttling up. It takes 100% of the snatch out of the situation.

Beyond that, you might look into the Fuel pressure regulator mod, or just buy one from Turbo City. I remember it helped immensely on my 5th gen with the throttle response.

http://www.turbocity.com/default.php?cPath=64

lastly, o2 eliminators and perhaps a Power Commander with a custom map. Definetly not cheap, but you can fix most anything if you've got a good tech on the dyno to make you a map.

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Thanks Rob, I appreciate your reply,

I'll get all that done ASAP. I tend to think it's also a function of "basic" fuel injection system vs carby's?

It's really the only thing I can fault the VFR on. I actually sold a Ducati ST4S & moved on (up) to the VFR, best move I've made in a while!

Cheers

Curt

No probs, stick around and post up some more, we don't bite. Much. wink.gif

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DUSTY THREAD ALERT!

. . .

Beyond that, you might look into the Fuel pressure regulator mod, or just buy one from Turbo City. I remember it helped immensely on my 5th gen with the throttle response.

http://www.turbocity.com/default.php?cPath=64

lastly, o2 eliminators and perhaps a Power Commander with a custom map. Definetly not cheap, but you can fix most anything if you've got a good tech on the dyno to make you a map.

Does anyone know if this is available for an '07? Turbo Cities site only has it listed up to '05. I know the '06+ had some changes to the FI/CPU controls so would a modified FPR make any difference?

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DUSTY THREAD ALERT!

. . .

Beyond that, you might look into the Fuel pressure regulator mod, or just buy one from Turbo City. I remember it helped immensely on my 5th gen with the throttle response.

http://www.turbocity.com/default.php?cPath=64

lastly, o2 eliminators and perhaps a Power Commander with a custom map. Definetly not cheap, but you can fix most anything if you've got a good tech on the dyno to make you a map.

Does anyone know if this is available for an '07? Turbo Cities site only has it listed up to '05. I know the '06+ had some changes to the FI/CPU controls so would a modified FPR make any difference?

The FPR should not have changed from '05 to present.

AFAIK, all the F.I. changes to the new(er) Vtecs were done inside the ECU.

Let me check the part numbers and see, BRB......

For the 2002-2005, it a 16740-MCW-003 which is superseded by the 16740-MCW-013

And for a 2007-2008, it lists 16740-MCW-013

So you're in business.

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Do you have to use a ball-bearing to push the seat in? (I ask because I've no idea what it looks like). Like, would a socket of the appropriate diameter do?

<{POST_SNAPBACK}>

There's not enough clearance between the frame and the butt end (spring seat) of the FPR for a socket; thus the ball bearing idea...

As for your thoughts and concerns, seadooloo, let me just say that I often write things satirically to get a laugh. Sorry if that doesn't translate well in forum posts. I too think Turbo City Tom is doing a hell of a job and deserves every dime he charges for his FPRs. Guys like him prove that ingenuity is not confined to manufacturer engineering staffs, and I was definitely kidding about the hate mail. Hilarious, wasn't it? :beer:

As far as doing a proper job of calibration... heeeyyyyy, just what are you saying about my hammer?? It's a finely tuned instrument, my friend http://www.vfrdiscussion.com/forum/public/style_emoticons/default/wink.gif Besides, I really just wanted to see what could be done on a 5th gen. If I'd screwed it up there would already be a new FPR on its way in the mail - probably from Turbo City! As it stands, I'm glad I did it even though I feel the method can be improved on.

I cant find the FPR for my 01 vfr800 fi can you send me a link or do they still sell them?

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I cant find the FPR for my 01 vfr800 fi can you send me a link or do they still sell them?

Turbo City no longer makes them.

But since they were just a squished OEM FPR your best bet would be just squish the one on your bike.

I have a spare I'm going to try mashing, then see how it does on my '01.

The PCV I have is running Autotune, so the FPR should just sharpen the tune.

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I went ahead and buttoned everything up and put a "T" in my fuel feed line permanently for easy fuel pressure readings later. I now have 40.5 psi fuel pressure (up from 36 psi stock. Shoot for about a 3.6-5 psi increase with this mod, or approx 10% over stock pressure), and the bike starts and runs beautifully.

Can you give us a picture of the "T" fitting in the fuel line??

I need to check the pressure on my '01.

I will probably want to do it on the '99, as well as a C14 that I'm instrumenting for some research work.

KISS principle would be best to get gauges on these bikes.

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My 2002 VFR suffered from the usual VFR problems of snatchy throttle off idle to 5000 rpm and the the incredibly annoying lean stumble at 4500 rpm. The solution, swap out the stock 36psi fuel pressure regulator with a 42psi regulator from a 2000 Honda Blackbird. It's an easy swap, less than two hours, just remove the air box to gain access. The bike is now a joy to ride below 5000 rpm. Totally transformed.

I ordered the regulator though Bikebandit.com (591149 part #).

Edited by KRSS800

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New part #

18:
REGULATOR, PRESSURE
591150 Usually ships within 1 to 2 business days $51.05 $44.41

http://www.bikebandit.com/oem-parts/2002-honda-super-blackbird-cbr1100xx/o/m151273#sch88174

Mite try this I like the concept ..


And Welcome KRS ...

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My 2002 VFR suffered from the usual VFR problems of snatchy throttle off idle to 5000 rpm and the the incredibly annoying lean stumble at 4500 rpm. The solution, swap out the stock 36psi fuel pressure regulator with a 42psi regulator from a 2000 Honda Blackbird. It's an easy swap, less than two hours, just remove the air box to gain access. The bike is now a joy to ride below 5000 rpm. Totally transformed.

I ordered the regulator though Bikebandits.com (591149 part #).

Welcome to the forum and starting out with a share right off the bat!!! Alright! Thanks for the info...

where did the 42 psi value for the BB come from, is this confirmed? That is almost right where I calculated I want to be... just slightly more.

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My 2002 VFR suffered from the usual VFR problems of snatchy throttle off idle to 5000 rpm and the the incredibly annoying lean stumble at 4500 rpm. The solution, swap out the stock 36psi fuel pressure regulator with a 42psi regulator from a 2000 Honda Blackbird. It's an easy swap, less than two hours, just remove the air box to gain access. The bike is now a joy to ride below 5000 rpm. Totally transformed.

I ordered the regulator though Bikebandits.com (591149 part #).

Welcome to the forum and starting out with a share right off the bat!!! Alright! Thanks for the info...

where did the 42 psi value for the BB come from, is this confirmed? That is almost right where I calculated I want to be... just slightly more.

I researched on the internet and my friend who is a Honda Motorcycle tech also researched it. Between the two of us this is what we found works. Simple and cheap.

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