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post #1 of 6 (permalink) Old 07-11-2012, 03:48 AM Thread Starter
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Fuel Consumption

Hi guys and regards from Bulgaria.
I bought my VN750-A5 - `89 two weeks ago from a second hand local dealer. It runs good and I`m verry happy with my choice. However I noticed a very high (I think) fuel consumption. It burns around 10 litters per 100 km (2.6 gallons for 62 miles) and I saw here as a normal consumption to be around 5 litters per 100 km. I checked the air filters and they look good and clean. Spark plugs and cables are also fine and the engine run smoothly. There are also no visible leaks (fuel or what ever) anywhere on the engine. I have some backfire upon deceleration but as I read in some posts it is normal. However, I noticed few things.
First, the air filters are a little oily... I dont know is it normal or it maight be caused by fuel spit from the carbs? The oily thing is transparent and clean, so it is not an engine oil for sure. The oiling is same for the both filters.
The second thing I noticed is that sometimes, istead of a few small backfiring (popping) upon deceleration, I have single loud BOOM from the exhaust pipe(s), like when the tyre blow and I don't consider this to be a normal thing.
So, where should I look for a problems and what are the common reasons for a high fuel consumption?
Thanks in advance for all responses and happy summer miles on your VNs :-)
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post #2 of 6 (permalink) Old 07-11-2012, 04:09 AM
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The "BOOM!!!" is usually going from a rich condition to a lean condition... try finding a fuel system cleaner like SeaFoam and runinng it through the fuel system a few times, If that doesn't clear it up, you are going to have to remove the carbs and clean them.

The air filters are supposed to be lightly oiled with 10w30 motor oil. you soak the foam in oil, then wring out all the excess.

If you haven't done so already, download the Kawasaki service manual HERE it is a large file, so be warned.. lol
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post #3 of 6 (permalink) Old 07-11-2012, 07:46 AM
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Anything over 70mph (110 KM/HR) and you'll see your milage drop dramatically. Pull your plugs and see how they are burning. Run 87 octane if it's available, not the higher 92+ and use a good fuel cleaner if seafoam is not available to you. That's a good place to start.

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post #4 of 6 (permalink) Old 07-11-2012, 01:20 PM
..have a vulcan good day!
 
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Quote:
Originally Posted by slimvulcanrider View Post
The "BOOM!!!" is usually going from a rich condition to a lean condition... try finding a fuel system cleaner like SeaFoam and runinng it through the fuel system a few times, If that doesn't clear it up, you are going to have to remove the carbs and clean them.

The air filters are supposed to be lightly oiled with 10w30 motor oil. you soak the foam in oil, then wring out all the excess.

If you haven't done so already, download the Kawasaki service manual HERE it is a large file, so be warned.. lol
x2 Slim
Excellent post !
WilliamTech

'86 VN750 13,700 mi -Stock
-Purchased 2008 w/8800mi
Replaced ALL Cables . Kuryakyn LED Voltmeter
SilverStar Ultra 9003/HB2 H4 Headlamp, Jardine Fwd Controls,
Iridiums DPR7EIX-9 & Wires, Tuxedo Mod, Coil Mod, P/U Sensor Mod, Fork Seals,
Splines Lubed - 11/4/2012 - MF AGM Battery
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Dampers went out @ 13+K !
After TOC MCCT's..... so amazingly quiet I discovered a rattling heat shield on my stock exhaust !
...have a vulcan good day!
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post #5 of 6 (permalink) Old 07-11-2012, 01:57 PM Thread Starter
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Thanks for all advices. I`ll run some fuel system cleaner for sure. I don`t think SeaFoam is available here, but I`ll get something considered as good. Thanks for the info about the oil in the air filters, I was seriously concerned that it is something comming from the carbs.
The lowest fuel octane here is A95 so I have to drive with it, wanting or not.
About the speed - this is my first season on the saddle and I`m trying to drive safe - smooth and not fast, with an average speed of around 50-60 mph, so this is not the cause.
However, I don`t have the knowledge to disassemble the carbs and clean them or do any repair, so if there is no serious effect from the fuel system cleaner, I`ll put the bike into the service box and will ask them to chek it. After all, it may need some carb balancing, syncronization or repair.
Thanks again for the advices.
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post #6 of 6 (permalink) Old 07-11-2012, 02:39 PM
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These carbs are simple... a blind man could rebuild them in his sleep... I too was hesitant to get into them, especially after looking at a parts brake down in the service manual. But after being talked into it from The Professor, I realized I was worrying over nothing. The most common problems with the carbs are stuck floats, or what yours sounds like is clogged jets... both are very easy fixes. But I would run the cleaners through first and see if that helps.
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