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Thread: Help me reclaim my gas mileage! Reply to Thread
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  Topic Review (Newest First)
05-14-2010 01:41 PM
dirtrack650
Quote:
Originally Posted by niterider View Post
The PO ussually does not know either. My air filters were all gone too. The foam had degraded to where there was nothing there. When the new filter came in I could not believe that all that foam had at one time been there.
This was my case too. I figured the foam reverted back to it's petroleum state and was consumed by the carbs and engine ;-(
(I cleaned the carbs shortly after buying the bike 10 years ago).

BTW I rode to work today, 32 miles of interstate, kept up with traffic or stayed ahead of the pack - much faster than I normally ride and achieved 35-36 mpg. My engine and carb tuning really smooths out @ 5500 RPM.

DT
05-14-2010 12:55 PM
niterider
Quote:
Originally Posted by Keemez View Post
What in the world? Who would DO that? You'd think the PO would at least TELL you about it instead of leaving it for you to discover.
The PO ussually does not know either. My air filters were all gone too. The foam had degraded to where there was nothing there. When the new filter came in I could not believe that all that foam had at one time been there.
05-14-2010 12:19 PM
Keemez
Quote:
Originally Posted by jimkonst View Post
I hate to admit it, but after I bought my Vulcan last October, I rode until March or early April before I checked the air filters. They were missing! The ears were empty.
What in the world? Who would DO that? You'd think the PO would at least TELL you about it instead of leaving it for you to discover.
05-14-2010 09:05 AM
artemis_f0wl Well, I was cruising faster than normal going down and back on my journey. I'll have to do the math to find out if I'm on par with what you all have said at the listed speeds.

I'll be going on another ride tonight. While not as long, I will have a passenger and a small pack with me who will likely stick to 70 on the freeway. I'll keep an eye on the mileage and keep you all posted.
05-14-2010 02:12 AM
VN750Rider/Jerry My bike does not feel slow at all (for a 750 v-twin) The 750 has outran a number of 1500 v-twins in stock configuration. I do not feel the need for more power, and while more power is always nice, I would not be willing to give up any engine reliability or longevity to get it. I use my 750 mostly for touring anyway.


As for not noticing any difference with and without the filters, that does sound strange, but that little square opening in the air filter housing may indeed be the limiting factor as far as air flow goes. The rubber ducts between the air filter housing and the airbox (or surge tank, as Kawasaki calls it) are also pretty small, but not as small as that little square hole. It's amazing that a 750cc engine gets enough air to run as well as the Vulcan 750 does through 2 of those little square holes. Hopefully you didn't get enough dirt in your engine to do significant damage. Around here, an engine would be completely destroyed in under 10,000 miles without air filters, even with the housings in place. That's why I use only well oiled stock filters. Except for the middle east, AZ has to be the dust capitol of the world. Jerry.
05-13-2010 05:45 PM
VN750_DawgsFan
Quote:
Originally Posted by jimkonst View Post
"I seriously doubt it is possible to get a noticeable increase in power from the Vulcan 750 engine just from changes to the intake and exhaust."


You bring up an interesting point. While it is logical that removing the filters would allow more air to enter, and lean out the combustion, new jets would be needed to get the mixture right, again. You should expect better performance...that is, more hp. Since you have a larger jet, you should expect greater gas consumption.

I hate to admit it, but after I bought my Vulcan last October, I rode until March or early April before I checked the air filters. They were missing! The ears were empty. Glad it was winter, with less dust. So I bought two filters last month, oiled them, squeezed them out, and installed them. I can feel no difference in acceleration or top end. I have not checked gas mileage. Without the foam filter, there should have been more air entering the mix than the jets were set up for. It should have run lean and hot and powerful. I don't think that it did. Not a scientific test, but I should have felt SOMETHING!
With the earshave, rejet, coastered and pickup coil mod.......you would actually be amazed at the difference. Before I got these thing done, the bike seemed slow, heavy and sluggish. After Lance did all the mods for me, I could not believe what a difference they made. It's now a totally different ride than when I bought it last year. After I got back from a test ride when Lance got done with the earshave, rejet and pickup coil mod, I only had one thing to say.......DAAAAAAAMN!

Of course all of this has cost me some loss in mpg, but it's really not very noticeable and was well worth it.
05-13-2010 04:39 PM
jimkonst "I seriously doubt it is possible to get a noticeable increase in power from the Vulcan 750 engine just from changes to the intake and exhaust."


You bring up an interesting point. While it is logical that removing the filters would allow more air to enter, and lean out the combustion, new jets would be needed to get the mixture right, again. You should expect better performance...that is, more hp. Since you have a larger jet, you should expect greater gas consumption.

I hate to admit it, but after I bought my Vulcan last October, I rode until March or early April before I checked the air filters. They were missing! The ears were empty. Glad it was winter, with less dust. So I bought two filters last month, oiled them, squeezed them out, and installed them. I can feel no difference in acceleration or top end. I have not checked gas mileage. Without the foam filter, there should have been more air entering the mix than the jets were set up for. It should have run lean and hot and powerful. I don't think that it did. Not a scientific test, but I should have felt SOMETHING!
05-13-2010 03:32 PM
VN750Rider/Jerry Well first of all, I'm sure you already knew the gas gauge is completely inaccurate. Mine stays on full for the first 65 miles or so, then drops like a rock. My '93 did the same exact thing.

I have V&H Cruzers (just recently installed) and upjetted to a 135 main/40 pilot. I have not noticed a change in mileage.

But. Even with the stock exhaust, I did notice a HUGE difference in mileage between an indicated 60 mph, and an indicated 90 mph (actual about 83 mph GPS) which is what most traffic runs around here in the left lane. It's almost the same difference you are talking about. At 60, I would hit reserve between 120-130, at 90 it was down around 80. The Vulcan engine really sucks gas at high speed.


Here in the AZ desert, gas stations can be few and far between. I have carried 3 gallons of gas in a jug in a T-Bag mounted to the sissy bar and luggage rack.


I decided to find out exactly what the Vulcan's range was while carrying extra gas, and started out with the petcock on reserve. At a pretty steady 60 mph on the open road, it sputtered to a stop at 152 miles, at 90 mph on the same road, it ran out at 118 miles. Wow. What a difference. This was with stock filters, pipes, and jetting.

I have no experience with the earshave thing, I actually like the ears. But my opinion is it is just for looks. I seriously doubt it is possible to get a noticeable increase in power from the Vulcan 750 engine just from changes to the intake and exhaust.

Now, N2O, a turbo, or supercharger might do it, but I suspect the engine wouldn't last very long. The VN750 engine is pretty well built, and has proven reliable when properly maintained and not abused, but it was designed and built for the power it makes in stock form. Jerry.
05-13-2010 10:45 AM
flitecontrol The Honda Rebel 250 gets 80 mpg, but you would probably need forward controls and a seat mod!
05-13-2010 09:00 AM
artemis_f0wl I did hit spots of rain but not even enough to get wet, just enough to know it was raining.

As for the VN800, that was my second bike (This is my 4th) and I DID love it! This 750 isn't my dream bike but it keeps me on 2 wheels until I can afford something more my size.

To be honest, the 750 is a little small, but with the addition of the engine guard and some highway pegs, it's much more bearable. As for the short legs, this is something I may not be able to bear. I ride in packs quite often. If I am always stopping the pack at each gas station we see, there is that much less riding we get in. Not to mention on this DC Trip coming up that I'll end up adding at least one if not 2 or 3 additional gas stops on the way. At an average of 30 minutes per gas stop (remember I'll be travelling with 20+ bikes), that will make our arrival time that much later and we're liable to miss the run to the Viet Nam Wall- something I don't want to miss and don't want to be responsible for making others miss!

The bottom line is that I think it's time to start shopping for another bike... I certainly want to keep my 750, but I think it's time for something at least twice the size.
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