Lousy Fuel Mileage- Help - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Carbs and Fuel System
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post #1 of 9 (permalink) Old 08-18-2010, 08:41 PM Thread Starter
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Lousy Fuel Mileage- Help

2002 VN750-A18

Goat removed; by Lance

R/R relocated by Lance

Iridium Plugs

Motul EX 100 lube

Purolator Pure One Filter.

Final Drive Replaced by Lance


Why am I only getting 34 mpg. I check my mileage every time I fill up.

I do not guess at the mileage I use a calculator.

I do not hot rod the bike; never been over 55 mph to date.

I have drilled out the plugs on the carbs; and they are at 2.5 turns.

Backfires; like crazy.

Runs smooth; up to 5,000 which is all I have turned the engine.

Stock mufflers; without the goat; loud, just ordered the Cobra Slip Ons from Dennis Kirk; should be here by next Monday or Tuesday.

I am looking for a deep mellow sound; probably should have left the stock exhaust on the bike.
Plugs are burning pure white; which tells me ; it is too lean.

Any recommendations on; jet sizes, turns out, etc; would be appreciated.

Other than above; the bike runs like a scalded dog; just backfires a lot.

Forgot to mention; I have also installed block off plates on the EGR; ports.

Stock Airfilters; Why would I want to remove what people are spending dollars to install the Kuraykin Intakes with the Flappers?????

Any comments or suggestions are appreciated.
By the way; trying to get in touch with Lance; any help would be appreciated.


Jim Bailey
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post #2 of 9 (permalink) Old 08-18-2010, 09:27 PM
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with all the backfirin sounds to me like your runnin lean and that could also lead to bad gas mileage.
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post #3 of 9 (permalink) Old 08-18-2010, 09:47 PM
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Lance`s dad passed away a week or two ago. He should be back with us in another week or so.


1991 VN 750 -"Cosmic Lady" or "Bad Girl"?
Purchased May 16, 2008
Approx.19,300km (12,000 miles)

H-D windshield
Relocated R/R
MF-AGM battery
Fiamm Freeway Blaster horns
F&S luggage rack and engine guard
Kury Offset Hiway pegs
July 13, 2016, Riding on the DARKSIDE now, Classic Radial 165/80-15

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post #4 of 9 (permalink) Old 08-18-2010, 09:48 PM
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Have you put in new exhaust crush gaskets and checked for exhaust leaks. That will make it backfire also. As far as the mileage I'm not sure about the jets so someone else will chime in on that except run some seafoam through it. It could be a gummed up carb. I notice quite a difference after running some seafoam or K-100 mg through mine, about 5 to 8 miles difference.

01' VN750
Jardine cross over exaust
Kyriakin grips and foot pegs
Modified seat and backrest
Luggage rack
Crash bar with Kyriakin pegs and extensions
Kumho 758 165/80-15 CT rear Dunlop 404 110/90-19 front
Coastered and air/fuel screws at 2.5 turns
Spline lube

93' VN750 getting TLC
Decals and mirrors
Coastered and air/fuel screws at 2.5 turns
Degoated with Harley mufflers
Duro 110-90-19 front 150-90-15 rear
Pick-up coils at .020
Spline lube
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post #5 of 9 (permalink) Old 08-19-2010, 12:21 AM
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i got crappy (29mph) rideing ( in the city) ran several tanks with sea foam im now running 49ish mpg , tho i have been getting on the old girl now and then

2010' voyager

2005 1600 nomad sold

1987 kawasaki vulcan 750 SOLD

1985 kawasaki vulcan 700 parts bike maybe
lots of hand guns
3 cagers doors kicked in
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post #6 of 9 (permalink) Old 08-19-2010, 10:02 AM
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Ditto for me! Seafoam improved my milage from 40mpg to 48-51 depending on the ride! Hopefully this will work for you and it's not something more! Good luck!

1986 VN 750
20,000 miles
MF Battery
Replaced Stock Turn signals
Starter Clutch
NGK plugs
MT66 Pirelli's
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post #7 of 9 (permalink) Old 08-19-2010, 07:38 PM
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i was getting 58 last year, this year about 52 till I changed to iridium plugs and now get 46 - 48. they seem to burn a little more gas but seem to be worth it. no goat and sportster pipes so I get a good bit of backfiring on decel but its all good!

1986 vn 750 aka "Huck Farley"
42,000 miles
Rick's stator and rr
Tuxedo stator cover mod
pickup coil mod
dampers replaced
agm m/f battery
Harley sportster exhaust, degoated
Hid conversion
splines lubed
custom "vn750.com" grill cover
NGK Iridium spark plugs

acct to mcct mod https://www.vn750.com/forum/showthread.php?t=17917

rekeying locks, https://www.vn750.com/forum/showthread.php?t=7309

stator replacement walkthrough, https://www.vn750.com/forum/showthread.php?t=11369
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post #8 of 9 (permalink) Old 08-20-2010, 05:45 PM
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I had an exhaust leak a little while back. It ran strong, but got real throaty sounding and kind of rougher than normal. Think my mileage dropped, but can't say how much.

If you try the exhaust, DON'T get the Harley-davidson gaskets. Even Lance328 has stopped using them, the Kawasaki gaskets fit better.
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post #9 of 9 (permalink) Old 08-22-2010, 09:02 PM
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I've used the HD gaskets twice, and haven't had any problems at all. They fit perfectly and work very well. And because of the way they're constructed, they have a much better chance of being re-used than the Kaw gaskets.

Just my .02 -- perhaps they have changed in the years since I last did mine.

Jim "Pick" Foster
Dixon, IL
VROC #9492
2010 Honda NT700V
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