fuel efficiency

[pcarrell]

I have a 1500 with V&H pipes and the rest is stock.  I live in Central Indiana, so flat and straight roads are everywhere.....so is wind.  On days without a lot of wind to contend with I avaerage around 46-47MPG, but factor in a nice headwind and the milage might drop to around 42-43MPG.
A lot of folks I've talked with say that messing with the F.I. actually makes things worse, but I suspect that has more to do with proper setup then anything.  Just my 2 cents.

[greenbarn]

I much appreciate all the feedback.  It helps me understand the issues.

Troll, you're obviously hitting on some success with your respiratory therapy on your 1500.  Hope you'll put all the details in a thread.  Sounds like a good deal.  I, too, love to tinker with stuff.

[kw-retrorider]

All: For the record....I have a stock 2002 - 800  with windscreen that I bought in November and have put about 1000 miles on. Low of 47.3 mpg and high of 52.1 mpg. That averages 50 mpg on the nose. Only mod I was thinking of was a K&N reusable filter instead of the current paper element.

[Troll]

Under the topic carb vs efi, I posted a fuel map that I stole from DynoJet that explains the fuel cell. Each combination of speed, throttle opening and engine temp, coupled with altitude, air intake temp and engine load put the map in a different cell. By increasing the incoming air charge volume, it allows the engine to run in a lower number cell that it would normally at any given time.
If, for example, you could get the fuel delivery cell for say 60 mph to continue to 70, and there would be no adverse running issues, the economy would increase . The trick part is making the open loop, fixed delivery system used on the Drifter to think it's getting the volume of air it would be at a lower speed, while actually giving it more. The greater the density of the air charge, the higher the specific power output. Think of a pile of gun powder set on fire, poof. smoke and a little spark, but restrain it in a firearm and it's BANG.  The difference here is that a carbed bike seems to react the same way, but for different reasons. A restricted intake on a carbed engine increases the venturi vacuum over the main jet, as well as decreasing the engine air charge volume. Ergo, a dirty air filter on a carbed engine will have a greater impact on fuel economy that a dirty air filter on an injected engine.

[alamogeorge]

Troll, what is the science (or redneck science) behind your mod? What makes it work?

[Troll]

So, I'm pretty happy, so far, with what I have done. I added up the total cost for hardware, etc. and it's about $110. I had been looking at various commercially available set ups, and they are at least $100 more than I have invested, have an open air filter element, stick out too far, or are just plain FUGLY....I ride in all weather (except ice, if I can avoid it), so an open element is out of the question. All I have to do now is some cosmetic stuff to hide the hose from the oil vapor separator. I was toying with the idea of lowering the center bolt a little to increase clearance with the fuel tank, but ultimately decided to machine away a small portion of the cover to accomplish that task....By the way, did you know that the air filter element for a 1500 will fit inside the element for an 800?

[Troll]

Ok, then...Just got back from a 100 mile road trip. I filled the tank before I left. I scribed a mark inside the fuel filler neck so I can always refill to the same level. My new air filter set up is the only change since last year. Wind from the south at about 30 mph, temp 60 deg. Speed was 70...I set the throttle lock at 70 and left it there... it's more bout steady throttle than steady speed at this point. Up and down hill, let the wind and terrain do what ever. One hill I have always lost 10 mph on only cost me 5 this time..Got to my first destination and refilled the tank.......39.9 miles... .768 gallons...51.953 mpg!!!!!!!!!!!!!I believe I have a winner here. The absolute best I ever got before was 48 keeping the speed down to 60...

[chief]

Based upon rumor... and how the 800 is being used... the 800 usually averages in the high 40's and the 1500 in the low 40's. Individuals will get better and worse based upon the bike, the rider, the weather, the terrain, the riding style, mods, etc.  I've seen claims of 25mpg up to 60mpg... still think the 40's is more typical.

[KsDrifter]

My 1500 is stock(performance wise)except for Vance & Hines pipes. Fully loaded, 2-up, we averaged right around 40mpg on our road trip last year. Some of the backroad, lazy stretches we hit as high as 47mpg(the exception, not rule, lol!) I've found that my mpg is directly affected by the twist in my wrist. I'm ok with that

My Vn900 gets 49-50mpg, 2 up or solo, I would imagine a 800 to be similar.

[greenbarn]

So 1500 stock gets in the low-40's range.

I'll sure be interested to see how that intake work turns out.  I imagine when you're done you'll post a thread in the mods section with pictures and supplies and all?  Or maybe you already have - but I didn't see it.

Or maybe open up an Ebay store "Troll's Drifter Mileage Plus Intake Kits". $99.95

[Troll]

Well, I have been tinkering with a new intake system to replace the stock airbox, and it seems to have made a big difference. I made a backing plate out of lexan to test the idea. I'm pretty happy with the results, getting almost 49 mpg on a run I have done many times where I was lucky to get 43...I'm going to go out this afternoon and try it again. The weather channel is predicting 60+ degrees, but a 30 mph south wind, so I'll only get a good reading in one direction. Oh well, at least it's warm. From the very beginning, I've gotten low 40s at interstate speeds, and even less in bad weather, so if I can get 45 @ 70, I'll be pretty happy. One thing I noticed, and I'm sure I'm not hallucinating...since I put on the high flow air intake the exhaust sound is louder, and has a bit of a "crack" to it...This is certainly an effect of more air in the combustion process..

[greenbarn]

With gasoline on a run-away train to $4 per 4 quarts, let's talk MPG.  Between the 800 and 1500, I'm assuming the 800 will get substantially better mileage.  Can anyone quantify what the stock fuel mileage would be, on the 800 and on the 1500???  To make it somewhat "standard" let's say easy riding, flat ground, not heavily loaded.

Now, how about you tinkers, what do you expect can be easily obtained with cheap/easy mods to increase MPG?  Troll, I see you talked in other posts about some efficiency mods on your FI 1500.  Let's say fairly easy, readily available stuff like pipes/air filter/ tuning etc, and not including something like custom computer programming, or CNC custom intake manifolds, or anything real radical.  I'm guessing +5 mpg or something smallish??

Have a great day.... God is good and spring is coming....