Gas milage problem - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 17 (permalink) Old 07-08-2008, 02:11 PM Thread Starter
 
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Gas milage problem

I just rode to St. louis and back (Champaign, IL), and I averaged only 29 mpg. What could affect the mileage that bad? The bike is a 05 750 that I bought about a month and a half ago. I bought it with 900 miles on it, and I have since put about 1200 miles on it. I also had to move the rear turn signals, and since then I have noticed that the brake light is on all the time (both filaments). Could a brake be sticking and ruining my mpg? I was averaging about 80 mph, and at about 6000 rpm.
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post #2 of 17 (permalink) Old 07-08-2008, 02:23 PM
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Check your brake switches first. The rear brake pedal has that plunger type and I can see it vibrating enough to the point that it pulls the plunger enough to engage the light. Also make sure your front brake lever pushes the switch in all the way when not engaged. On your center stand does your rear and front tire spin freely? If so your fine there. As for the milage yeah thats way off the norm. Has the PO done an ear shave to it or any type of carb work (ie. bigger jets). Check floats, look for leaks, new plugs? Something isnt right here. Your math correct? I get about 150 miles on a complete tank, whats your trip saying between fill ups?

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post #3 of 17 (permalink) Old 07-08-2008, 02:39 PM
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hmmm... I thought when I gt 36 it was bad.. I tried octane 89 the other day- 48.6 mpg...
have you tried sea foam to clean the fuel system?
good luck with trying to fix your problem and keep us updated!

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post #4 of 17 (permalink) Old 07-08-2008, 08:44 PM
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80mpg??? Most here get 50 or less. Is it running on both cylinders? Unless it's running rough or extremely rich (black smoke out the exhaust) you should be getting 45-50 on US 87 octane at 60-65 mph. Mileage drops appreciably at higher speeds.

Jim W
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post #5 of 17 (permalink) Old 07-08-2008, 09:41 PM
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Hey jaking, your MPH and RPM's align well (80 mph @ 6000 rpm). Shows me you were in 5th gear. If you were riding your brake it could suck up gas, but not so much as to give you only 29 mpg. I usually get about 50 mpg straight highway in the 70 - 90 mph range. What mileage do you get just around town?

Maybe you have a gas leak. That would certainly ruin your mileage. Or maybe your carbs need adjusting. Also, check your tire pressure.

By the way, nice that you bought an '05 750 with only 900 miles on it. Should be good as new. Wonder why the PO sold it. Could help you diagnose the problem. Good luck. Keep us posted...

Rubyrick

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Splines lubed when tires installed at 10,650 miles
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post #6 of 17 (permalink) Old 07-08-2008, 09:47 PM
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Quote:
Originally Posted by jakinq View Post
I just rode to St. louis and back (Champaign, IL), and ...... I was averaging about 80 mph, and at about 6000 rpm.

And there is your answer..(you came to St. Louis and didn't stop to visit me?)

As RPM's increase, sot does gas consumption..on the Vulcan, once you cross that 4500 rpm threshold, things get bad ...exponentialy. This means that at 4500 rpms you are getting say 50 mpg, and at 5000 rpms you are getting say 44 mpg. but at 5500 rpms you are getting 36 and at 6000 you are getting closer to 30. As you said "average" you would have to mean that at times you were going faster than 80mph and at times slower..so , given this, unknown wind factors, unknown aerodynamics of the bike and rider..(do you have a windsheild? Did you have luggage?) it really is not hard to believe you got 29 mpg...

At 900 miles you engine is not even broke in yet...but not enough information to judge if you are actualy correct in your milage figures.

I alway noticed that once I went past 5500 rpms I could actualy watch the needle in the gas gauge go down........


Go take the same trip again , but do not let the bike go over 4800 rpms in any gear and see what kind of milage figure you get.

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post #7 of 17 (permalink) Old 07-08-2008, 10:24 PM
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Is it possible that you never went above 4th gear and reved higher to get the speed? I am getting under 40 around town but that's a lot of up and down shifting.
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post #8 of 17 (permalink) Old 07-08-2008, 10:43 PM
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Doing 80 at 6000rpm you will eat gas fast.
If you keep it over 5K your milage drops fast.
Mine did the same thing on the way down to the Gathering

Chad Falstad "Hawk"
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post #9 of 17 (permalink) Old 07-08-2008, 11:10 PM
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I don't know why, but I haven't gotten less than 42 mpg ever on mine. I often get 50 or more mpg straight highway. I usually ride a bit fast, too. And I'm meticulous about monitoring my gas mileage with each fill-up. I'm that way on my tacoma as well.

By the way, check out the following article from 2001 comparing 9 cruisers including the VN 750.

http://www.motorcyclecruiser.com/roa...son/index.html

Our 750 had the BEST GAS MILEAGE, reached the FASTEST SPEED in the 1/4 mile acceleration and had the 2nd fastest 1/4 mile time (beat by the Intruder by a mere 0.28 sec but we blew the intruder away in top speed by 13.9 mph).

Rubyrick

MY BABY...
'05 VN750
16,000 miles +
Kawi tank bib
Kawi rear rack
Small windshield
DEKA M/F battery
VN750.com Grill Cover
LED license plate frame
Clear Alternatives LED brake light
Cortech mini tank bag on rear rack
Pirelli MT66 Tires: 110 front / 150 rear
Splines lubed when tires installed at 10,650 miles
Splines lubed again at 14,400 with stubby valve stem install

Place your mouse on the X below and drag to the O

X
Even though you can't see Him, GOD is there! O
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post #10 of 17 (permalink) Old 07-09-2008, 08:36 AM Thread Starter
 
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Thanks for all of the help. To answere a couple of questions: I barely went above 85, and I was getting above 40mpg around town. I do have a windshield, and saddle bags. I did fix the brake light issue (actually re-read the manual! ). I put it on the center stand last night, and the rear wheel would only turn about 1 and 1/2 times; the front wheel was a little better, but I did hear some squeaking. I have put about 2000 miles on the bike in the last couple of months, and, like I said before, it only had about 900 when I bought it. Should I change all of the lubricants, and would that make a difference?
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