MPG crash - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 15 (permalink) Old 09-11-2013, 07:20 PM Thread Starter
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MPG crash

I was getting 48 - 50 MPG for 2000 miles. Then the last 2 times I filled up, first was 44 mpg then today 36 mpg. I checked plugs, not black or wet. Looked to have a few miles on them, brown baked on. Petcock is not leaking, and oil does not smell like gas. I just did the spray sea foam, and added it to tank. Will see if that helps, if not I'll keep the petcock off except when riding. Any thing else I should check?
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post #2 of 15 (permalink) Old 09-11-2013, 07:41 PM
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Originally Posted by smltownr View Post
I was getting 48 - 50 MPG for 2000 miles. Then the last 2 times I filled up, first was 44 mpg then today 36 mpg. I checked plugs, not black or wet. Looked to have a few miles on them, brown baked on. Petcock is not leaking, and oil does not smell like gas. I just did the spray sea foam, and added it to tank. Will see if that helps, if not I'll keep the petcock off except when riding. Any thing else I should check?
Did you change riding styles and were you doing heavy traffic riding recently compared to open road riding previously. On longer trips I average 53 mpg and just running around locally with getting on it a bit more and short bursts winding it out I average 43 to 45 mpg. Also, did you recently change the brand of fuel you are using now. When you fill your tank try to do so when you know you will be using some of that new fuel before shutting the bike down so you can fill it all the way up where you can see that you are refilling it to the same point each and every time. Not filling it to the exact same point will cause a variation in your calculations.

and always remember, "Ride until you rot!"
**Really not sure if the Big "C" is back right now
but having to face the fact that this is a lifetime routine
going forward. Five operations done and it still continues.

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New ride: 2009 Victory Vision Arlen Ness Signature Series
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post #3 of 15 (permalink) Old 09-11-2013, 08:27 PM Thread Starter
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I always do the same thing. During the week I run back roads to work and back, 48 MPG. Weekends I run 50% back roads 50% highway, 50 Mpg. Always fill up at same station during this last week. Other stations 'on the road'. And I always fill it up to the bottom of the round neck, so accurate within 1/10 gal. 12% less first fill up, then 28% less with second. I'm fairly anal when it comes to accuracy. Comes with my job.
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post #4 of 15 (permalink) Old 09-11-2013, 08:35 PM
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im guessing stuck float valve, does the bike have a prime? Switch it to prime if it does and see if fuel comes out anywhere

kenny

Merc
2000 Vulcan Drifter 800
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post #5 of 15 (permalink) Old 09-11-2013, 08:42 PM Thread Starter
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No prime, just off; on; and res. Saturday I am going on a 300 mile ride around northern Arkansas. So, I will be able to see what MPG I am getting with 'fill up and ride'. And I'll turn it off when I stop. I really miss the 50 mpg :-)
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post #6 of 15 (permalink) Old 09-11-2013, 08:50 PM
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Is it hot there now?

I think I'd put in some new plugs ( if they aren't iridiums) and check your airfilter.
There's too many variables when trying to compute mpg figures. Tempature, humidity, wind, tire pressure (check that too) gas quality, etc...

Only real way to get an accurate figure is over several tankfulls ....and remember its just an average.

36 seems low however. See if it goes back up after your SeaFoam treatment.

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post #7 of 15 (permalink) Old 09-11-2013, 09:06 PM Thread Starter
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Been hot. 90+ and 75+ humidity. But been that for months LOL. Saturday is to be 78F, sunny. Darn good day for a long ride. Will get more data then. But 28% loss in one week......Something is amiss. Strange, it still; starts, idles, runs, and accelerates the same as when getting good mpg.
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post #8 of 15 (permalink) Old 09-12-2013, 01:19 AM
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I noticed my MPG dropped quite a bit on mine for a bit, and then I noticed that one of the little 90degee nipples that fit into the petcock came loose and was seeping gas. After I tightened this back in, my mileage went back up to an acceptable average.

Just another thing to keep in mind.

......I'd rather wake up in the middle of nowhere then in any city on earth.

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post #9 of 15 (permalink) Old 09-12-2013, 10:23 AM
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I found this dandy of an article:

http://auto.howstuffworks.com/fuel-e...mmer-fuel1.htm

Kenny

Merc
2000 Vulcan Drifter 800
Roadhouse classic 2 > 1 exhaust
Okie Smokie intake config
Changed jets
52K miles or so, always going up
Corbin Seat
Painted flat black winter '12
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post #10 of 15 (permalink) Old 09-13-2013, 09:34 AM
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Coast enricher stuck on?

Sticking brakes are usually the first thing I check for when someone has lost mpg and the engine is thought to be running well.

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