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Gas mileage on a 98 5th gen

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My 2000 has 97K miles...I'm 245lbs, ride with full bags and get 40-42mpg in touring mode.. On gas in the twisties 32-36mpg.

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20 hours ago, zupatun said:

My 2000 has 97K miles...I'm 245lbs, ride with full bags and get 40-42mpg in touring mode.. On gas in the twisties 32-36mpg.

That seems to agree with what I'd expect. The reason I don't really know is I've made it a habit to never check my mileage when I'm having a fun time carving up the twisties.

 

There is no point in spoiling the fun with practibility. Your Mileage May (And Probably Should) Vary. :wheel:

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On 1/5/2019 at 4:09 AM, Zarquon said:

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!

I had an RF900 for 18 years, they are a good solid machine but a little uninspiring next to a V4. Have a look at the emulsion tubes in the carbs, mine wore oval over 50,000km and the fuel economy went to crap (plus fowled plugs at low revs) but it was an easy fix. 

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3 hours ago, Terry said:

I had an RF900 for 18 years, they are a good solid machine but a little uninspiring next to a V4. Have a look at the emulsion tubes in the carbs, mine wore oval over 50,000km and the fuel economy went to crap (plus fowled plugs at low revs) but it was an easy fix. 

Gotcha on that, thanks Terry. I spent 12hrs cleaning the carb rack just to make it run and I still have some issues with it. Damn bike has standed me twice, flooding on deceleration. I have dropped the needles one stop and it got better. I now have an optimised needle and jet kit on order hopefully this will set things right along with a heap more time in the ultrasonic bath and some new carb seals. I will check those tubes again when I get back into the carbs. The bike is for my girl, its got a low seat for its size, good for her... I like making old things new again, so its good for me too! Needless to say her mum hates it?

 

You can't please all the people all the time. (A Blue Gen5 VFR pleases me!)

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10 hours ago, Zarquon said:

Gotcha on that, thanks Terry. I spent 12hrs cleaning the carb rack just to make it run and I still have some issues with it. Damn bike has standed me twice, flooding on deceleration. I have dropped the needles one stop and it got better. I now have an optimised needle and jet kit on order hopefully this will set things right along with a heap more time in the ultrasonic bath and some new carb seals. I will check those tubes again when I get back into the carbs. The bike is for my girl, its got a low seat for its size, good for her... I like making old things new again, so its good for me too! Needless to say her mum hates it?

 

You can't please all the people all the time. (A Blue Gen5 VFR pleases me!)

Factorypro do a good info page for CV carb setup, and are where I bought the emulsion tubes for my 900. You should be able to pull the carb tops off and the slides out, and just look at the brass tubes in the carb floor. The tubes can be replaced from inside the float chamber.

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Hi, sorry for not replying immediately to this interesting debate.

Well, what can i say...When i did the flapper mod, i got an immediate advantage at very low rpms (under 3500 rpm, so to say). The V4 is not the smoothest engine at those rpms anyway, but now it's much better. Don't know why it behaves in this way, it should be the opposite (open flapper valve = roughest behavior at low rpm), but currently i will keep the flapper mod.

Snorkel mod - just a matter of better noise 😉

 

Gas mileage? It's always the same - bad. You go slow, you go fast, it seems that the injection system was originally set to always squirt as much gas as possible in the cylinders, regardless of the conditions. I drove my bike for half tank at hilarious city speed (3000-4000 rpm) and the result was always the same , a miserable 235 km (146 miles) from a full tank, excluding reserve.

 

Just yesterday i heard another 800 Fi owner - he had one non-catalyzed (1998) and one with catalyzer (2001). Well , he said exactly the same things - the '98 has a better punch at midrange but has crap mileage and runs always quite rich (the exhaust is always a bit blackened after some hundreds of km).

 

Fuelly mainly shows results from US bikes, the few non-US bikes have worse result about gas mileage. Exactly for this reason, i would like to know if there is some differences between the 1998-1999 Italian-European ECU and the USA one.

 

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AFAIK, there is NO difference between the US 48 state ECU's & the rest of the world for the 98/99 models. There is a possible difference for the 00/01 models as in Europe we got HECS-3 emissions kit for Euro2 compliance (not sure =if that was included in US models) & HISS ignition chip system for theft prevention.

 

Synchronising your starter valves correctly improves the smoothness of the engine everywhere, especially cleans up the free revving nature of the engine.  Gas mileage is hard to improve on the VFR its its one bad point. But on a stock setup 00/01 model you should get 200 miles from a tank, hits reserve around 185, even when ridden in a spirited fashion. When cruised you should get 200 before reserve. My tuned up version hits reserve around 160ish miles, but has reached 180+ when cruised on a eurotour through the Alps.

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1 hour ago, Mohawk said:

AFAIK, there is NO difference between the US 48 state ECU's & the rest of the world for the 98/99 models. There is a possible difference for the 00/01 models as in Europe we got HECS-3 emissions kit for Euro2 compliance (not sure =if that was included in US models) & HISS ignition chip system for theft prevention.

 

Synchronising your starter valves correctly improves the smoothness of the engine everywhere, especially cleans up the free revving nature of the engine.  Gas mileage is hard to improve on the VFR its its one bad point. But on a stock setup 00/01 model you should get 200 miles from a tank, hits reserve around 185, even when ridden in a spirited fashion. When cruised you should get 200 before reserve. My tuned up version hits reserve around 160ish miles, but has reached 180+ when cruised on a eurotour through the Alps.

 

As said, it seems that every '98 owner in Italy gets bad mileage, regardless of the injectors conditions or the speed. Y2K catalyzed models are known for having a MUCH lower fuel consumption. The bike runs great anyway.

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I have installed a Power Commander unit on my bike....but it's not a modern one. It's quite a old piece of vintage electronic, being a PC II, made in 1999-2000 (found a new old stock one, still with sealed box, for one hundreds euros). The box itself is quite self-explaining about the age of the item:

 

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The installation is very easy - just unplug the original harness, and plug the PC II betweem ECU and original connector (no additional plugs are present on this old device). It sits quite well under the seat, but it was not possible to hide the connectors in a less invasive position. The plastic hooks under the seat are perfect to fit the wire properly.

 

1581721710_WhatsAppImage2019-02-24at10_49_19.thumb.jpeg.ea219dd527b8ba55d6f8eeaa0f4834e7.jpeg

 

After a bit of struggling with adapters (the thing has a serial port!) and with unusable software, i finally managed to install the proper files and to connect the PC II to my notebook. I have installed a map previously tested by a member of the Italian VFR club, and now the bike can run for almost 280 km until the res light - that's a gain of 40 km. Performances are almost unchanged, just a slight loss of stamina and smoothness at low rpm. Now the bike stays in the range of 16 km/l (almost 38 mpg), and that's an acceptable mileage, albeit not impressive for sure. Now it's a VFR-BNSO (Very Frequent refuelling, But Not So Often). 

 

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I regularly use Seafoam in all my vehicles.  The objective is to keep the intake valves free from oily deposits as best I can, without the flapper/PAIR mods.  Yes, I'd love to witness the intake honk derived from said disablement of the former and latter, but I just don't want to queer the set up unless there is a gob of increased bhp/torque to be had.  Since there doesn't appear to be, I'm leaving it alone.  To each his own, except for Seafoam.  Use it regularly, and you and your mill will be *happy*.  Just my opinion which means nothing to anyone but me.

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On 12/31/2018 at 10:50 PM, GreginDenver said:

 

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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BS. The air box is VERY restrictive. Check out my threads & mods which prove it empirically, rather than the rants of some armchair warrior. 

 

Honda like everyone else has to comply with noise & emissions regs. The 98/99 models had a lower emissions standard applied & gas was cheaper then. But 33mpg (I assume Imperial MPG =4.546L) is bad. I get that from my much more powerful VFR when ridden hard. The guy is not riding that hard.

 

Back to the OP’s issue. Downloaded maps are garbage. Fuel injectors have very different deliveries, so a custom map is the only way to ensure a consistent  Air Fuel Ratio & to see how your engine fuelling is performing as stock before a remap.  The 5th gen single pintle injectors are simple devices & not prone to blocking unless left for long periods unused.

 

Good luck.

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20 hours ago, Mohawk said:

BS. The air box is VERY restrictive. Check out my threads & mods which prove it empirically, rather than the rants of some armchair warrior. 

 

Once again, the 5th Gen VFR air box has 2 intake paths for a very good reason: from idle to about 7,000 RPM the rubber snorkel provides a level of airflow which causes the air box achieve a resonate frequency in that RPM range.  When the air box hits a resonate frequency it boosts intake efficiency, which boosts torque in that rev range.

 

After about 7,000 RPM the 5th Gen air box opens up the flapper.  This changes the resonate frequency equation, moving the air box resonance point to the upper end of the engine's rev-range.

 

Also, the 5th Gen VFR's rubber snorkel intake is long, which is exactly what you want for the lower end of an engine's RPM range.  The Flapper side of the air box intake is short, which is exactly what you want for the upper end of an engine's RPM range.

 

As others have pointed out, the 5th Gen air box acted in a similar way to the VTEC system in the later generations of the VFR (this also explains why the dual-path air box was dropped in the VTEC versions). 

 

 

 

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OK, so you obviously believe in the helmholtz resonance theory that manufacturers espouse to convince people that they have not restricted your engine to meet noise & emission regs etc. 

 

The VFR air box is to small, it’s the wrong shape & wrong material to create a helmholtz reasonance or any meaningful frequency effect. My dyno charts show no losses anywhere with a gutted big air box, with the filter moved to the top & the factory intakes eliminated, that adds about 3L to the intake area volume. Just by moving the filter to the top of the air box it added 5hp to my engine ! So you will have a hard time convincing anyone that the factory setup is best.

 

try keeping your delusions to yourself, unless you have empiracle evidence to back it up. 

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^^

(this also explains why the dual-path air box was dropped in the VTEC versions). 

 

Umm no, only the latest 8g has done away with the flapper BS, and still has dual path.

Check a parts fiche for each gen (5,6,8)

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No need to be harsh here Mohawk.  Honda didn't make something this complex on a whim. They had to have some reasoning behind it, else they'd never have dome something requiring that many parts.

 

And your data isn't exactly apples to apples.  Your larger airbox with a substantially greater volume doesn't have the compromises that Honda were trying to work with. I'm guessing they chose the airbox based on what they could cram under the tank with accessibility for maintenance, manufacturing concerns, fit to the throttlebody, and all of that associated stuff -- maybe including emissions and noise. But they aren't "restricting" anything. They just did what they did within the parameters they had to work with.

 

I haven't seen this -- are there direct dyno comparisons from a stock airbox with and without the flapper and snorkel mods? Those charts might be interesting to see.

 

And just interesting. Not to fight about, just to see because it is interesting to know how something like yanking the snorkel really affects intake. Most of us aren't going to go to the effort you did. One of the joys of your experimenting is that I can see what the difference is when you make a dual path intake or something ridiculous like that, and how it really works, but that's all a cumulative comparison that includes previous mods on your bike.

 

Airboxes are like a capacitor in the hydraulic system. Changes in volume affect how they work, regardless of how restrictive they might be. I won't be able to get into it because I'm wholly unqualified to explain it and want to make that clear.  There are a lot of voodoo magic elements to them, as well. But a significantly larger volume creates a slower change from state to state so an un-snorkeled larger capacity box is not a fair comparison.

 

And, I think the point here, aren't we talking about lower than average mileage? Not all VFRs have shit mileage, this bike gets 10mpg lower than some other folks with stock bikes

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Sorry didn’t mean to be harsh but bs is bs. There are direct comparisons with dyno numbers that shows no noticeable difference between stock & de-flapped. But that is with NO fuelling mods. When fuelling is modified to suit, then the de-flapped version makes more power higher up, with no losses. 

 

Anyhoo 33mpg is poor, regardless.

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Are there charts for this?   It would be an interesting experiment to see the results from.   And I find it odd that a deflapped would make more power. With the flapper open it's pretty much the same short path.  Seems counterintuitive to me.

 

I'll be honest, part of the reason I got the my bike tuning on my rapidbike was to see how things changed the sensor data. But the other part was so I didn't have to worry about the fussy fuel mapping BS, which really is voodoo magic. Or tedious, which gets expensive if you don't have unlimited dyno time available to you. Just like that, if I shove a dB killer in my can for someplace like LagunaSeca, or my air cleaner starts to get dirty, I will still get a good mixture, without thinking about anything.

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