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Behavior for maximizing fuel economy

Old 05-30-2010, 09:44 PM
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Behavior for maximizing fuel economy

Hey Everyone,

I know the fuel economy topic is old an tired here. So please forgive me, I have done a fair bit of searching, and I think this question has a different enough perspective to be worth discussing.

What I'd like to understand is, for the people who get the best fuel economy here, how do you use your bike when you're getting those numbers? Obviously "go easy on the throttle," but I'm trying to suss out more specific info.

Specifically, what engine speed ranges do you cruise at - in the city, and on the highway? When you're in low speed situations (25-30mph), what gear/rpms are you in?

Also, what is your strategy or tendency at least, for warming your bike up, and closing off the choke?

I believe I get the worst fuel economy of anyone here who has shared. I get 20-23 city. If I ride like a grandmother on the highway, I can eek out 33 mpg. My bike is pretty bloody close to bone stock - one .020" shim on the needles, and TPS set to 490. Everything else is factory, and miles is very low (<3k). This isn't about the settings and tuning though, there are enough threads on that. Here I'm just asking people to share the details that they find get them the best mpg.

Here are my details: First of all, I do a lot of *very* short trips - like two miles. Second, I usually let my bike warm up to 150+ before I start riding (a factory mechanic convinced me that 90% of the wear on most bike engines happens when riding not warmed up). So obviously I'm using a lot of gas not moving. But as for riding behavior, I try to keep it between 3k and 4k, and don't normally twist the throttle very far - generally 1/3 throttle to accelerate.
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Old 05-30-2010, 09:57 PM
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Here are my details: First of all, I do a lot of *very* short trips - like two miles. Second, I usually let my bike warm up to 150+ before I start riding (a factory mechanic convinced me that 90% of the wear on most bike engines happens when riding not warmed up). So obviously I'm using a lot of gas not moving. But as for riding bhavior, I try to keep it between 3k and 4k, and don't normally twist the throttle very far - generally 1/3 throttle to accelerate.
Yuck.. First off, that mechanic is and idiot.

Most of the wear in any engine occurs in the first 20 seconds till oil pressure builds up, once there is oil pressure you don't worry about wear. Now till the bike is warmed up you don't want to really romp on it, yes since the oil could be slightly thicker and thus not doing it's job well enough to protect against red-line shifts, but for standard riding, after 20 seconds or so there "ain't gonna be no difference" other than the amount of gas you waste.

And extended idling of the superhawk on the kickstand has been called awful for it.. It has been blamed by several race teams for causing failures on the track. (I can't verify this just repeating what I have heard)

And finally RPM's only matter to a certain amount... Odd but true. It takes x amount of horsepower to move the bike, and x amount of fuel to create that amount of horsepower. So if you are in 1st or 6th going a specific MPH the fuel consumption difference will only be that of the extra power needed to spin the motor faster. (and a few pistons are lighter than an entire bike) Yes there will be a measurable difference in fuel use, but not 10mpg difference.

More fuel is used in acceleration than in cruising.. so lots of stops and starts will burn way more fuel than just cruising.

Last edited by lazn; 05-30-2010 at 10:05 PM.
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Old 05-31-2010, 08:46 AM
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Rama recently posted information about the ignition timing on the VTR. There's about 20 degrees or less advance at and below 3,000 rpm. At 4,000 rpm, there's at least 31 degrees of advance. You might get better fuel economy by keeping the revs closer to 4,000 rpm rather than 3,000 rpm. I'll defer in advance to the tech wizards on the forum.
I'm with lazn on the issue of an extended period at idle to warm up the bike. I suggest getting off the choke as soon as possible and riding the bike gently until it reaches operating temperature.
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Old 05-31-2010, 08:59 AM
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I see the best mpg's in sixth at 4k plus rpms so 65 mph and higher. They drop slightly if I am below 4k rpms. I get between 40 to 45 mpg here. In town stop light to stop light I drop into the low 30's. So yes acceleration makes for a heavy hit in economy. Also worth mentioning I get about 38 mpg when riding twisty roads. I usually don't blast straights so there is not what I would say really hard acceleration.
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Old 05-31-2010, 09:15 AM
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+1

I think you answered your own question here. You do lots of short trips and you let the bike warm up before each ride. That's the problem. I agree with Lazn. Get your gear on first, start the bike, run it 15-20 seconds, and ride away. Get off the choke as soon as you can.

Try that for a tank or two. I'll bet you see 40mpg with easy riding.
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Old 05-31-2010, 09:49 AM
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Originally Posted by lazn View Post
And finally RPM's only matter to a certain amount... It takes x amount of horsepower to move the bike, and x amount of fuel to create that amount of horsepower.
Well, big picture that is correct. But this point specifically bypasses the exact details I am trying to suss-out. Engines do not have constant efficiency across the rev range or across throttle positions for a given engine speed. The real question is, at what engine speed and throttle position does the engine have the least inefficiency? And really, we want to know that "... for a given power requirement?"

That's actually a continuous spectrum, so there are an infinite number of questions. But it roughly simplifies to:

At what engine speed and throttle position does the engine have the least inefficiency when producing:
  1. enough power to maintain city speeds?
  2. enough power to maintain highway speeds?
  3. enough power to gradually accelerate?
  4. enough power to moderately accelerate?

Question 2 is somewhat moot because you are probably out of gears beyond 65mph. But it is probably valid for 55-65-ish.

-Avram
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Old 05-31-2010, 10:25 AM
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Nobody is going to be able to give you exact answers to your questions - Comedo and Cornandp came close as anyone can based on experience.
If you think you are getting worse gas mileage than you should be and you want som quantitative answers you should start with a Dyno run and see what your A/F ratios are. Your bike could feel good yet still be rich in the ranges you most often operate in. You wouldn't think so based on the state of tune you said your bike is in, but the A/F will tell you instead of guessing.
For myself I do very little urban riding so I can't comment there, yet I have seen other posts that indicated city driving could result in 28 -30. For me, my experience mostly mirrors cornandp's
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Old 05-31-2010, 10:52 AM
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Originally Posted by Hawkrider View Post
+1
I agree with Lazn. Get your gear on first, start the bike, run it 15-20 seconds, and ride away. Get off the choke as soon as you can.
The routine that works for me is get on the bike and start it (so it's not idling on the side stand) put on my helmet and gloves. At that point it is time to go. As soon as you are rolling the choke is pushed in and just take it a bit easy until the temp comes up a bit. This has worked for me with no problems in the 80k I've put on my bike
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Old 06-03-2010, 09:59 AM
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+1 again
I've seen guys who've been wrenchers for 40 years get on a cold bike and ride off. If they're not worried about it, why should I be?
I've found that I get the same mileage on just about any type of gas I run - no matter what. In town - there is no gas mileage....it's gas footage. I'm doing good to get 90 miles on a tank in town. A few posts up guys said running right around 4k rpm works great, I second that. That's where my bike is happy running anyhow. If I'm in a hurry but not really running hard, I'll shift at 4500 or so. Highway, I cruise at about 80 (yes, I'm a cop..lol) and with factory gearing that's about 4500rpm. I'm ranging from 40-45mpg on highway if only highway. I'm running a K&N filter which a lot of guys on this forum say is worthless. On their set up it may be, but it works well on mine, and when it gets dirty I lose mileage. I'd say if you run around 4k rpm like everyone's said, you should get around 40mpg or a bit better out of a stock setup. Anything less and I'd be willing to bet you've got something not working right. But then again, I'm just a shade tree mechanic with no real knowledge...that's just what I've found. Best of luck!
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Old 06-03-2010, 10:16 AM
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Here is a big one, before I installed thre factory pro b1.1 kit, I got 31 or 32 mph. now I get ~37. The PO had it WAY too rich and forget to put the retaining spring on one of the needles. My bike is much smoother now too.
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Old 06-03-2010, 10:41 AM
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When my digital temp gauge hit 100 degrees F, I push in the choke and I'm on my way. I keep the revs under 5k or so 'till it's fully warmed up.

The way you get the best mileage from a VTR (or anything else) is to run highest gear at lowest RPM possible without lugging the engine and being VERY steady and gentle with the throttle had. Keeping it under 65 mph on the highway I've gotten over 50 mpg, but what fun is that? If I wanted to get the best possible mileage on two wheels I'd have bought a 250cc bike.
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