Gas Mileage versus RPM

[Troll]

Ok, here's picture or 2 looking down the outlet of the muffler towards the inlet. Took a Christmas light out of one of my Wife's big candles and stuck it in the pipe....(I put it back, so she will never know). It looks like the pipe narrows, but it doesn't .
The inlet is 1 3/4, the outlets are 1 1/8 ID each...no obstruction, so LOTS of airflow!

[David Baker]

Troll, Thanks for the info, I'll check it out.

[Troll]

    I posted all I did under the title fuel injection mods. Pics of the air cleaner backing plate, using an vn800 K&N air filter with the top cut out...It's been a long trip, but so far, what I have learned about this open loop system and how weather, altitude, and load affect it has been interesting, if not completely rewarding. The results have been good, generally. A few missteps, but over all, positive. I looked at the air cleaner mod you are talking about with the big round car filter, and decided it's just too ugly for me, and I ride in all weather, so an open air filter element is out of the question. I removed the left side air box and the duct after I did some pretty extensive testing with a prototype backing plate made out of Lexan. I did not do this for more power, but I did get a boost over 70 mph, that's quite surprising. Power used to fall off noticeably as the rpm reached 4000, which is where the air flow from the 4 valve heads starts to make a difference. The engine now pulls strongly all the way to about 100 mph in 4th gear....that's about 5,000 rpm. More air in means more power out, at least in the case of this bike. Another thing I noticed was that after the mod, the exhaust sound was quite a bit louder. I was running a Peace Pipe, but now I have a stock system installed, and it's pretty loud, too!
I have 2 stock systems, now. I got one from Texas pretty cheap, but the chrome was not real good. I did some poking around and found another one from Florida for what it would cost me to re-chrome the first one.  Here's a note for those of you who want to "gut out" the original system...there's nothing to remove! I now have 2 mufflers, both of which have NO BAFFLES in them. They are identical, so it's hard to believe that 2 bikes from different states would have the same surgery on their mufflers. Shining a light in the inlet end shows NO RESTRICTION all the way through...Harley systems have baffles in them that people routinely ram a 1" piece of pointed re-rod through. I thought I'd have to do that with these systems, but no...   I'll try to get a picture, but I don't think it will work.

[45 Bravo]

I have always been a mileage freak in our cars, trying to eek out as much as I possibly can..

I had a 99 ford expedition, 5.4 liter v8 I could regularly get 22-24mpg on the highway, later traded it for a Nissan pathfinder, 3.3liter v6. The break over point was 62mph, below that, got 19mpg highway, at 65, got 16.8mpg, and it went down the faster you went..

Got a pt cruiser, 2.4 liter 4 cylinder, thought it would do good.....

Thought...
In town, 15mpg, highway on a trip with 2 people, 22mpg.
With the a/c turned off and drafting behind an 18 wheeler, it might get 25mpg.

Bought my wife a 2012 ford focus, 2 liter 4 cylinder, rated at 38mpg.
With the 2 of us, we regularly turn 45mpg at 70 mph.
It has a advanced transmission, I am learning to drive it for higher mileage..
Air temp and density have a lot to do with it. I can travel a route 70 miles one way during the day, and get 44.5, make the same trip at night, get 39.4, also maybe the higher amperage draw from the lights..

The best I have done was on the Natches trace, 50 mph limit, good road, 62.1mpg according to the computer over a 180 mile trip, in daytime, ac off, got photos to prove it.
Also duplicated the results (61.9mpg) with the general manager of local dealership riding along over same route..

But here is the weird thing, I can drive here to memphis(70 miles) on the interstate, alone, and get 38.6, come home, same average mileage both ways (I bought a computer off Craigslist) then 2 hours later (about 3pm) make the same trip with the wife, and get better mileage(44.2) ..

I would figure, being 200 lbs lighter would get better mileage, but it don't..

Like our drifters it seems to like a certain rpm range where it gets the best mileage, above or below that happy place, it gets worse economy..

Any ideas?

[David Baker]

Troll, You mentioned ( I played with TPS voltages (which helped below 60 mph, but not above) and finally made my own air cleaner backing plate and ditched the restrictive stock air box system.) Do you have any photos or details of this? I've been contemplating modifying the air intake by installing one of the open screen old school auto triangle style air cleaners. Did you do away with the left side cover and move everything to the right side?

[CDNRatMan]

Troll were can I find that were I can change it for the 800, I looked but can not find it... Thanks

[45 Bravo]

That's about where i shift (when i concentrate on it) but it is soo easy to slip back into the low rev habit...

Oh, the gas mileage app i use is called road trip. available on the apple app store.
there are both a free version and paid version (the paid version allows export features and a few others)

there may be an android app also, but i don't know..

45 Bravo

[Troll]

2500 rpm= about where I shift, anyway

[45 Bravo]

By suggested shifts, I mean the revised ones, at 2500~ rpm, not the low numbers in the manual.

20-25 shift to 2nd, 35ish 3rd, 50 to 4th, 60+ to 5th.

45 Bravo

[Troll]

Ok, then. This is something I've been working on, almost since I got the bike. My 1980 FLT would get 50 mpg pretty consistently. As a matter of fact, the last rip I took on it I went 235 miles on 4.5 gallons of gas. I had reconfigured it to turn 3000 rpm @ 70 mph from the stock settings (something you can do with chain drive you can't with either belt of shaft). I had ditched the stock carb. for a blockhead Kehin C-V, and made my own jets ( I sure miss carbs). The Drifter, which turns about 200 rpm less @ 70 in overdrive, never got more than about 40 on the highway, until I started fiddling.  I played with TPS voltages (which helped below 60 mph, but not above) and finally made my own air cleaner backing plate and ditched the restrictive stock air box system. The result was immediate and dramatic. The first time I went out this year with the new system, holding a steady throttle with my vista cruise, a 44 mile interstate trip yielded 51 mpg. I was ecstatic. I made lots of trips this year of the long distance variety, and with a mix of 70+ and 60+ speeds, the average has been around 47 mpg. I routinely have the idiot light come on now, at about 180 miles, rather than 140. I had, up until recently, been running the Cobra "peace pipe" and It was pretty good, but the tip of the pipe was always black/sooty, indicating too rich a mixture. I installed a stock system about a month or so ago, and this seems to be the missing piece to the puzzle. The tips of the 2 pipes inside the fishtail are gray, not black!  Last Saturday, I went for a ride to some Vet memorials. I rode 97 miles and used 1.8 gallons of gas...53 mpg! I always shift, if I'm just riding without trying to impress some pony car driver who wants to race, on the whole numbers...20 mph to 2nd, 30 to 3rd, etc. The factory suggested speeds for upshifting are : 1-2, 12 mph, 2-3, 19, 3-4, 25, and 4-5, 31...got this right out of my owner's manual, so take it for what's it's worth.

[ChilliDrift]

That's pretty interesting. I usually get 100 miles on my combined city hi way tank before the light kicks on. I've got V&H long shots baffles removed with a power commander and K&N air filter. On the hi way I get 120 and bingo light. 3 to 3.2 gal. I don't short shift anywhere except; n town. And generally ride it pretty hard on the hi way to get up to speed.  I had a chance to ride my friends stock bike and there was a big difference in HP. It was pleasantly quiet. But definitely lacked in horsepower compared to what I was accustomed to.

[DC]

It would be interesting to see a study (gather data and plot) that includes as many variables as possible and record the mileage for city/highway.  This would be hard to do though, as everyone rides differently.

Still, a spreadsheet showing the several major exhaust brands (stock, Brand 1, Brand 2, Brand n), intake (stock, Brand 1, Brand 2, Brand n), windshield vs. no windshield, tire brand model and riding pressures, oil (synth or dino), ambient riding air temp, etc., that yield X mileage.  This could problably be plotted on a 3D graph and maybe some trends would start to show.  In other words, certain combinations of mods or no mods yield better mileage. This would be better than the anecdotal info that we are used to seeing.  But then again, it's nice to dream.

[45 Bravo]

Factory exhaust, previous owner removed the cold weather solenoids, no other changes to the factory breathing arrangements.

No power chips, no engine enhancements.
25,000 miles on the bike.

45 Bravo

[DC]

Just curious, any intake mods?  What exhaust do you have on it?

[45 Bravo]

Hello, I know this has been covered before, but while on my long ride to Kentucky i had a lot of time to think about things.

I grew up riding a HD 51 police special of my dads, and i also had a 76 sportster, and a long list of transverse mounted 4 cylinders.  I have always short shifted the v twins, i just seems natural that way, and i like the way the inline 4's sound good when revved like they were meant to be.

On here I have heard everyone talking about their mileage, how good it is, how bad it is, and I kept thinking what the correlation between them could be.

On my daily ride to work i ride 1.5 miles exactly each way, 3 or 4 times a week i go out of my way just to make the ride last a little longer.
In this time, i have been short shifting my drifter, and i can count on my bingo fuel light coming on between 63 and 68 miles on the odometer, this commute is in town, with a max speed of 45.
when i fill up it takes about 3.25 gallons every time.
This averages to less than 20mpg in town.

Both before and after the trip i have made concerted efforts to shift at the SUGGESTED shift points, even on the short trips.
I have an app on my phone and ipad that track my mileage and stuff.

During the trip i averaged 45.6mpg, over twice the mileage in town.

During the times that i shifted at the suggested speeds, for the entire tank, in town, the bingo fuel light would come on at 80 - 85 miles on the odometer, and take 3.25 gallons for the fill up.
that puts it in the 25mpg range, in town.

I kept trying to think of a way to post this in a helpful, coherent way, but never could, so i figured just post it as a set of disjointed observations..

45 Bravo