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Discussion Starter #1
I'm getting some rather poor gas mileage and am looking for some feedback.
Bike: 2002 S4 foggy Monster:
Stock MPG ~ 43.
MBP heads installed, dyno tuned, stock ECU ~ 29 (Ran out 2x w/~83 miles on trip)
MBP heads, PCIII, dyno tuned ~ 25

Bike runs well and strong. I thought it might have been rich on the low end w/o PCIII but gas mileage has gone down since install. Most riding is commuting and general street riding (4-6K RPM). Any thoughts/ideas?
 
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Discussion Starter #2
Re: Poor Gas Mileage (foggy123)

4-6K rpm? Aren't you lugging the engine? That might explain the poor milage.
 
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Re: Poor Gas Mileage (rotty900ss)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rotty900ss »</TD></TR><TR><TD CLASS="quote">4-6K rpm? Aren't you lugging the engine? That might explain the poor milage.</TD></TR></TABLE>

Not even close. On a big twin like that, 2k is lugging. My motor pulls from 3500 on.
 
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Re: Poor Gas Mileage (Phil 998)

To extend this question, what kind of gas milage are you guys seeing on your bikes?

I am seeing about 35 mpg on average with my '03 999 when crusing around in 5k .. 6k range. I have termi half-system and mapped PC3usb.

Usually i can go about 110..120 miles on a full tank before the gas warning comes on, which i think leaves me with about 0.75 gallons left.

Just curious to know what other people are getting.
 
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Re: Poor Gas Mileage (foggy123)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by foggy123 »</TD></TR><TR><TD CLASS="quote">I'm getting some rather poor gas mileage and am looking for some feedback.
Bike: 2002 S4 foggy Monster:
Stock MPG ~ 43.
MBP heads installed, dyno tuned, stock ECU ~ 29 (Ran out 2x w/~83 miles on trip)
MBP heads, PCIII, dyno tuned ~ 25

Bike runs well and strong. I thought it might have been rich on the low end w/o PCIII but gas mileage has gone down since install. Most riding is commuting and general street riding (4-6K RPM). Any thoughts/ideas? </TD></TR></TABLE>

i get around 115 or 125 miles out of a tank of gas. how long ago did you have the pcIII map done? was it after the head work or before? try and ride with the pcIII off for a tankful if you can and see how that effects your mpg
 
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Re: Poor Gas Mileage (jbraslins)

I get around 35-40mpg and if cruising on the interstate (which isn't very often) it gets better. The 998 gets better mileage than my 95 916 did, and the 998 would leave the 916 for dead.
 
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Discussion Starter #7
I went from Whittier to Palmdale and back. Average spead around 70-80 and got 47 mpg. On the tach that is about 5k. I have K&N, stock airbox, Ferracci pipes. However, I just installed a techlusion fuel injection box and I am waiting to see what kind of miliage I get now.
 
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Re: (corsastrada)

35-40+ mpg with SPS cams, 35/30 valves, corsa ECU and PCIII. I noticed when I had my trimmer set high (like +60), my mpg went to shit: +30ish mpg. It is trimmed to +30 now, and I need to build a new map.
 
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Re: (corsastrada)

PCIII was just added. Sequence of mileage is as listed.

Right now I'm looking for or plan on stopping for gas at ~75 miles which is only about an hour. When the bike was PCIII dyno'd (30 miles on a dyno), it got ~ 19mpg. BTW- my warning light works intermittently.


No lugging at 4k but bike really takes off at 6k until the rev limiter hits at 10k.

Headwork was 37/31 valves, port & polish, etc. Stock cams as of now.

Any other ideas????
 
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Re: Poor Gas Mileage (foggy123)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by foggy123 »</TD></TR><TR><TD CLASS="quote">I'm getting some rather poor gas mileage and am looking for some feedback.MBP heads installed, dyno tuned, stock ECU ~ 29...Any thoughts/ideas?</TD></TR></TABLE>

Hmmm...ported heads flow more air requiring more gas. More gas equals less mileage. Hmmm...
 
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Re: (foggy123)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by foggy123 »</TD></TR><TR><TD CLASS="quote">PCIII was just added. Sequence of mileage is as listed.

Right now I'm looking for or plan on stopping for gas at ~75 miles which is only about an hour. When the bike was PCIII dyno'd (30 miles on a dyno), it got ~ 19mpg. BTW- my warning light works intermittently.


No lugging at 4k but bike really takes off at 6k until the rev limiter hits at 10k.

Headwork was 37/31 valves, port & polish, etc. Stock cams as of now.

Any other ideas????</TD></TR></TABLE>


(PCIII was just added) how was your gas mileage before the PCIII?
 
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Re: (oneducs)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oneducs »</TD></TR><TR><TD CLASS="quote">
(PCIII was just added) how was your gas mileage before the PCIII?</TD></TR></TABLE>
~29MPG w/ headwork.
~43 stock before headwork.
 
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Re: (oneducs)

imo the dynojet cruise fuel ratio of 13.5 is a bit rich, but it should use way less fuel than that small richness would cause.

too lean can cost you fuel economy as easily as too rich, as you end up using more throttle opening to get the same power. generally these things cruise at 100km/h around 10 degrees throttle opening. so it's either very wrong in that range, or it's very wrong elsewhere.

what does the pc map look like? that should give you an indication of what they did to get the change. if the idle trimmer is set prior to the pc mapping then it shouldn't matter at all - the mapping process should over ride that. that's what the mapping process is.

what sort of compression does it have? that can drop your economy if it's low. but that's a huge change. i'd be looking for a problem, not just a tuning issue if the pc didn't help. if the pc map is good all over then it should be pretty good.

a cylinder to cylinder variation can cause really high fuel use - maybe there's an issue there. what's the cam timing like?

ported heads, even if you use the throttle a lot, shouldn't really increase the fuel use that much.
 
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Re: (brad black)

Brad-
Cams were suppose to be degreed with head work. Squish was tightened when heads were installed. I'm taking a shops word for the work above.

Dyno chart from PCIII below.

 
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Discussion Starter #16
Re: (foggy123)

huh, sounds like you all need to switch to carbs
I was getting 52 with my jet kit and now 47 with Keihins
 
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Discussion Starter #17
Re: (Monster Man)

I've got a 2nd bike that gets better mileage.


I just like my Foggy to make it at least 100 mile w/o worries.
 
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Re: (foggy123)

IMO, check the following:

Make sure the return hose from the fuel pressure regulator isn't kinked.
Check fuel pressure to make sure the fuel pressure regulator is working properly.
Prolly check cam timing as well.
Get a leakdown done on the motor to make sure nothing got botched on the motor work.

I noticed my mileage dropping steadily as the miles racked on, then it rebounded after doing the first valve adjustment.
Usually I get low-mid 40's on my S4, dropped to high 30's as it approached the first valve adjust.
 
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Discussion Starter #19
wot fuel mixture has no relevance to part throttle mixture, and that's where the issue is.
 
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Discussion Starter #20
Re: (brad black)

Throttle position across, RPMs going down by 500, 1000, 1500, etc.
Shouldn't having the bike PCIII mapped take care of part throttle mixtures?


0 0 0 0 -8 0 0 0 0
0 0 0 0 0 0 0 0 0
0 -7 5 0 0 0 0 0 0
0 12 13 -5 12 16 18 10 20
0 -6 14 -21 -17 12 17 12 25
0 0 -14 -21 -8 0 23 -6 -9
0 0 -4 -23 -13 -13 -40 -12 -13
0 0 -3 -18 -8 -31 22 6 -15
0 0 -15 -18 -7 0 15 11 11
0 0 -7 -6 2 5 8 9 8
0 0 0 -2 8 9 18 29 6
0 0 0 -8 8 2 -6 16 6
0 0 0 10 7 8 33 17 15
0 0 0 10 3 5 -3 10 13
0 0 0 0 4 5 10 13 0
0 0 0 0 6 9 16 16 9
0 0 0 0 4 8 10 17 12
0 0 0 0 7 8 8 15 2
0 0 0 0 9 7 20 11 10
0 0 0 0 0 2 1 7 -1
0 0 0 0 0 0 0 0 0
 
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