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Gas mileage on a 98 5th gen


cuoccimix

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From what I read Chapter 21 only serves to "explain" why Honda did what they did. No mention is made of noise reduction, which

I believe is the main reason for it. On almost any engine improving air flow to the engine is one of the first things done to improve

performance. That, basically, is what removing the flapper valve and snorkel do, allow more, and cleaner, air flow to the throttle

bodies.

 

I am curious why you think improving air flow won't help the mid to upper range power. Or is your contention that removing the flapper

valve and snorkel won't clean up and increase air flow? Or do you feel the ECU can't compensate for increased air flow?

 

Helping get more air into the engine, is as important as getting the air out of the engine, as with an aftermarket freer flowing exhaust.

 

We may never agree on this, but I don't mind discussing it. :beer:

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Okay, let's talk/debate...

 

Maybe, before we start talking actual technical issues, we should try to work out a couple of what I'm seeing as "barriers to communication".

 

First, you seem to be very strongly self-convinced that the VFR's airbox was designed the way it is for noise abatement reasons.   I find this to be very strange, I've read a a lot of the published literature on the VFR and have never seen any mention of this, where in the world did you get this idea from?

 

Second, it seems that you want to discount the information in the Service Manual Chapter 21.  Why do you think Honda went to the trouble of including the Chapter 21 information?  Can you give me a good reason why I shouldn't take Chapter 21 at face value?

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I've been around motorcycles for many years and watched the industry struggle with noise control issues. Very few companies

allow unrestricted intakes due to noise issues, same with exhaust systems. The VFR is a noisy motorcycle due, in part, to it's

gear driven cams. I figure the restrictive intake is one of their efforts to lessen the overall engine noise. JMO of course. But I

also think Honda put a positive spin on it, just because that's what they do. Have lemons? Make lemonade. Have to restrict air

intake for noise purpose? Make it sound like you're doing it for a reason other than that.

 

No, I don't want to discount the information in Chapter 21, but there's only about 2 pages of that chapter that refer directly to the

operation of the flapper valve and snorkel. I'm not discounting any of the information in Chapter 21, I'm just saying the info about

the flapper valve and snorkel may not be the complete reason. What would be the purpose of explaining that it's there for mostly

engine noise abatement. If they said that, the first thing anyone would do is pull it all off. Look at what happens to quiet exhausts.

 

Again, there's lots of good information in Chapter 21, but very little mention/explanation of the flapper valve and snorkel. And the

reason there's not very much, is, IMO, because it doesn't really do very much.

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46 minutes ago, FJ12Ryder said:

I've been around motorcycles for many years and watched the industry struggle with noise control issues. Very few companies

allow unrestricted intakes due to noise issues, same with exhaust systems. The VFR is a noisy motorcycle due, in part, to it's

gear driven cams. I figure the restrictive intake is one of their efforts to lessen the overall engine noise. JMO of course. But I

also think Honda put a positive spin on it, just because that's what they do. Have lemons? Make lemonade. Have to restrict air

intake for noise purpose? Make it sound like you're doing it for a reason other than that.

 

It sounds like you're just gonna double, triple and quadruple down on your "noisy intake" idea.  And not only that, you're gonna go all conspiracy theory (Honda doesn't want us to know this stuff... black-helicopters, chem-trails). 

 

And you're doing this in spite of the fact that Honda very plainly explains (in Chapter 21) that the VFR800 airbox is not restrictive at all.  I mean look, read, understand... here it is in plain black and white:

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Okay, I'm done, you obviously don't have anywhere near an open mind and are not willing to discuss without getting

very confrontational. I have my opinion, and you have an opinion. They don't agree and I can dig it, but you just can't

seem to get along with someone not agreeing with you. So take your hyperbole and I'll go my merry way.

 

I thought you might be open to a discussion, but I was wrong. Have a good one. Maybe see you down the road

sometime. I sometimes make it out through Denver.

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If you have a look at Honda's own parts fiche for 2017 8g vfr800 with the same airbox you will note not that they DO NOT supply the variable intake valve anymore and have replaced it with a cap, ie deleted it. Now I do not own a new 2017+ 8g so I'm not sure if they even have the valve anymore.

Credits to Grum for doing a thread on this several months ago

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[stepping into shithole]

Man.... I know I'm going to regret sticking my toe in this shit hole......

 

RC51 - have a very similar flapper in their air box.    It is interesting to note that I never saw a race-prepped RC51 with an active flapper (including Honda supported teams).  However street-going RC51's sold by Mother Honda that were subject to EPA regulations did come with an active flapper.

 

I don't think anyone has ever found the "smoking memo" signed by Soichiro, but the common consensus is that the flapper exists solely to satisfy an EPA noise regulation that are done at a certain RPM that is determined by an equivalent speed determined by gearing, or something like that.    Many posters here and on the RC51 sites have modded the flapper and I don't recall anyone posting any evidence that the mod resulted in any repeatable changes in performance.

 

It has been years since I've read any of these discussions, so I'm going off memory.   Google "Motorcycle Flapper Mod" and you'll have a week's worth of reading on the subject across about 5 product lines and thirty motorcycle forums.   I personally buy into the noise control thought (and my calibrated Mk 20 eardrum confirmed intake howl).  Consider this.... The marketing teams would have "variable intake" on every piece of literature if it even resulted in 1 hp or 1 lb/ft benefit.... never saw a pamphlet that mentioned it.  I've also never saw a dyno curve that showed any difference between before/after either.  I thought this discussion ended at least fifteen years ago.   Go figure?

 

[stepping out of shithole/]

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On 12/30/2018 at 9:21 PM, polaris956 said:

My "normal" mileage for my 1998 VFR is 40-44mpg on 93 octane.  Only mod is Vance & Hines SSR2 slip on.  

 

If that were my bike it would be a huge red flag.  I monitor my mileage for two reasons

1.  Curiosity

2.  Great indicator of driving habits and or motorcycle health.  

I used high octane fuel when I got my first fifth gen assuming it had a built-in timing advance. Once someone wised me up on that, I've run 87 octane over 200,000 miles of fifth gen riding. The first engine, still in excellent, never-opened- up condition, had 105,000 miles on the odo when it was KIA'ed by my first deer confrontation.

No need to waste your money.

And welcome to the asylum from The Land Of Interesting Weather. By your choice of weapon it is obvious you have great taste in mc's.  

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9 minutes ago, Lee 2002 said:

[stepping into shithole]

Man.... I know I'm going to regret sticking my toe in this shit hole......

 

RC51 - have a very similar flapper in their air box.    It is interesting to note that I never saw a race-prepped RC51 with an active flapper (including Honda supported teams).  However street-going RC51's sold by Mother Honda that were subject to EPA regulations did come with an active flapper.

 

I don't think anyone has ever found the "smoking memo" signed by Soichiro, but the common consensus is that the flapper exists solely to satisfy an EPA noise regulation that are done at a certain RPM that is determined by an equivalent speed determined by gearing, or something like that.    Many posters here and on the RC51 sites have modded the flapper and I don't recall anyone posting any evidence that the mod resulted in any repeatable changes in performance.

 

It has been years since I've read any of these discussions, so I'm going off memory.   Google "Motorcycle Flapper Mod" and you'll have a week's worth of reading on the subject across about 5 product lines and thirty motorcycle forums.   I personally buy into the noise control thought (and my calibrated Mk 20 eardrum confirmed intake howl).  Consider this.... The marketing teams would have "variable intake" on every piece of literature if it even resulted in 1 hp or 1 lb/ft benefit.... never saw a pamphlet that mentioned it.  I've also never saw a dyno curve that showed any difference between before/after either.  I thought this discussion ended at least fifteen years ago.   Go figure?

 

[stepping out of shithole/]

Good for you Lee. This is obviously a case of::beatdeadhorse:

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18 hours ago, GreginDenver said:

I heard that the EPA fired their motorcycle intake noise regulation from the "grassy knoll".

Oh No! Not another Greg starting a conspiracy sub-thread. :ohmy:

 

Now I've got to state that this comment was full meant in jest. 

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11 hours ago, boOZZIE said:

If you have a look at Honda's own parts fiche for 2017 8g vfr800 with the same airbox you will note not that they DO NOT supply the variable intake valve anymore and have replaced it with a cap, ie deleted it. Now I do not own a new 2017+ 8g so I'm not sure if they even have the valve anymore.

Credits to Grum for doing a thread on this several months ago

 

If one engine has VTEC and the other does not do you think these two engines might need a different airbox configuration?

 

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9 hours ago, Lee 2002 said:

RC51 - have a very similar flapper in their air box.    It is interesting to note that I never saw a race-prepped RC51 with an active flapper (including Honda supported teams).  However street-going RC51's sold by Mother Honda that were subject to EPA regulations did come with an active flapper.

 

I'm wondering if "race-prepped" motorcycles are the best source of modification ideas/guidance for people who ride motorcycles on streets.

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1 hour ago, GreginDenver said:

 

If one engine has VTEC and the other does not do you think these two engines might need a different airbox configuration?

 

I don't understand,  1998 5g has v.a.i & no vtec, 2000 5.5g has v.a.i & no vtec, 2003 6g has v.a.i & vtec, 2007 6.5g has v.a.i & vtec, 2014 8g has v.a.i & vtec, 2018 has ??? & vtec 

And with what airbox.. the same yes?

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Check out the website Fuelly. The average mileage figures for the 1998 VFR are almost exactly what I am getting.

Sent from my SM-G955U using Tapatalk

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A Big Aloha to all, and a Happy 2019.   Gas Mileage question on the VFR's!!!!!  I have 6 VFR's, had 7 but sold my 2002 last year.  Starting with my 86 RWB 750cc and then my 87 White 700cc up thru the generations to my 2003 Silver.  All of them get regularly 45 to 50 MPG depending on the Loud Handle Positioning. Some have the air box mods, some do not, doesn't make any MPG difference.  I did an Iron Butt a few years ago by myself from San Antonio to west of Phoenix in 15 hours. 1050 miles. Here is my point to this Viffer MPG question, its all about the LOUD HANDLE!!!!  On that day of my Iron Butt I was running pretty much 100 to 110 MPH all day and into the night.  Had to stop a lot for gas!!! Was getting 30 MPG at that sustained speed so had to stop def before 150 miles on the trip odo.  One stretch thru Texas I pushed it too far, didn't see any gas stations coming up, finally pulled into a gas station, the Viffer to took exactly 5.5 gallons. It was completely empty!!!!  The only reason I made it to that station was due to easing off on the LOUD HANDLE, slowing down to 45 MPH for about the last 20 miles.   Normally 45 to 50 MPG for my scooters and all my friends that also ride VFR's.   By the way, the Yellow models are the fastest, everyone knows Yellow is a fast color.  Have a safe and enjoyable 2019.   Renzo in Kau, Hawaii

Dragon.jpg

Big Woman, Sport Bike.png

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On 12/30/2018 at 4:14 PM, thtanner said:

 

I second everything you posted.

 

 

Seafoam direct into the TB and a smoke show should help clean them up. Always impresses the neighbors when your vehicle becomes a smoke machine /s

I just read and interesting comparison of engine cleaners, Seafoam is among the best. Techron is another one that worked great. 

 

-Tony

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On 1/1/2019 at 3:15 PM, Motorenzo said:

A Big Aloha to all, and a Happy 2019.   Gas Mileage question on the VFR's!!!!!  I have 6 VFR's, had 7 but sold my 2002 last year.  Starting with my 86 RWB 750cc and then my 87 White 700cc up thru the generations to my 2003 Silver.  All of them get regularly 45 to 50 MPG depending on the Loud Handle Positioning. Some have the air box mods, some do not, doesn't make any MPG difference.  I did an Iron Butt a few years ago by myself from San Antonio to west of Phoenix in 15 hours. 1050 miles. Here is my point to this Viffer MPG question, its all about the LOUD HANDLE!!!!  On that day of my Iron Butt I was running pretty much 100 to 110 MPH all day and into the night.  Had to stop a lot for gas!!! Was getting 30 MPG at that sustained speed so had to stop def before 150 miles on the trip odo.  One stretch thru Texas I pushed it too far, didn't see any gas stations coming up, finally pulled into a gas station, the Viffer to took exactly 5.5 gallons. It was completely empty!!!!  The only reason I made it to that station was due to easing off on the LOUD HANDLE, slowing down to 45 MPH for about the last 20 miles.   Normally 45 to 50 MPG for my scooters and all my friends that also ride VFR's.   By the way, the Yellow models are the fastest, everyone knows Yellow is a fast color.  Have a safe and enjoyable 2019.   Renzo in Kau, Hawaii

Dragon.jpg

Big Woman, Sport Bike.png

Welcome to the asylum Motorenzo. That is one fine example of the best generation. Having had two Y2Ks I'd have determined they do make one younger and sexier but I'd have argue about that fastest color thing. Everyone knows red has been scientifically proven to be the fastest color.:wheel: YMMV

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Oh sure Maxswell, bring that scientific approach into the argument about the fastest color!!!!  Who ya gonna believe, some nerd or the seat of your own pants???   Heres Collin Edwards from a few years back... Yeller all over the place.....and fast!!!!!  No gas mileage however:goofy:...

Colin Edwards, Arai Helmet.jpg

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On 1 January 2019 at 10:38 AM, FJ12Ryder said:

Okay, I'm done, you obviously don't have anywhere near an open mind and are not willing to discuss without getting

very confrontational. I have my opinion, and you have an opinion. They don't agree and I can dig it, but you just can't

seem to get along with someone not agreeing with you. So take your hyperbole and I'll go my merry way.

 

I thought you might be open to a discussion, but I was wrong. Have a good one. Maybe see you down the road

sometime. I sometimes make it out through Denver.

Hi FJ12Ryder.

I'm with you on this, and at the risk of also stepping back into the "shithole", just wanted to update you on the Flapper Removal from my 8th gen.

My reasons for removing the system was based on Honda's removal of the system from the 2017 model, I was keen to simply remove some clutter from under the tank Provided I didn't induce any detrimental effect on performance, fuelling or fuel economy, have had an open mind about this systems pros and cons for ages - technical and personnel opinions abound with the system! This is a subject that has been thrashed to death :beatdeadhorse:

I can only say that my bike is SUBJECTIVELY as good if not better without it. I can definetly (at least) confirm after approx. 10,000kms without it that my fuel economy is as good if not better.

I personally believe that the state of your air filter (cleanliness) will have greater effect on performance than what the Variable Intake System can offer - Subjectively speaking. It's no surprise to me that Honda have removed it. YMMV!

Now - also stepping out of the "shithole"!!!

Cheers.

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I recently bought a 2000 model (with cat) had 36000km on it. It came with an aftermarket slip on exhaust. KThe fuel milage was about the same as what you quoted in your initial post (pretty crap). First job I did was add a volt meter then cleaned the pair valves (choked with Carbon), then balanced the idle valves and dismantled and serviced all the rear end drive components serviced the front and back brake calipers and replaced the pads and fluid. This all did nothing noticable!

 

I then added liquid moly injector cleaner a bit at a time in each tank of fuel until the bottle was empty. That did nothing noticable too!

 

I put some new BT30 evos on it and then I did a 6000km road trip from Sydney to Cairns the fuel economy got better and better as the trip wore on!

 

(Blew the RR in Brisbane now have a lighter wallet and mosfet type RR hard wired with beefed up wiring).

 

So I think a long ride might do the trick... it'll be good for your constitution if nothing else.

 

I get about 18km per litre at highway speed now. 

 

Note Even the Blue gen 5 VFR's burn up their RR's

 

🙂

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6 hours ago, Stray said:

Wow - 6,000km road trip sounds awesome! 

The big one is still to come. I believe that a circuit of Australia is about 14000km. But the first job is to restore an RF600R (barn find) for the girlfriend to ride. Her old GS500 was reliable but couldn't keep up!

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