SuzukiSavage.com - Print Page

SuzukiSavage.com
/cgi-bin/YaBB.pl
General Category >> Rubber Side Down! >> Why don't we get better MPG?
/cgi-bin/YaBB.pl?num=1216806763

Message started by Jay on 07/23/08 at 02:52:43

Title: Why don't we get better MPG?
Post by Jay on 07/23/08 at 02:52:43

OK. I want to know why we don't get better MPG. For that matter, why all motorcycles don't get better MPG.
Take for example a Toyoto Yaris. Curb weight 2290lbs, a 1.5 liter engine, and 29/35MPG.
Our Savages are under 400 pounds wet, with a 0.65 liter engine, and we get somewhere in the neighborhood of 55-60mpg stock. WHY?!

I realize that factory estimates of MPG don't factor in certain variables, and nowhere is that more apparent than on motorcycles; weight of the rider, flex of the right wrist, mods, etc., but a stock factory to stock factory comparrison still leaves us on the short end. I mean, the Yaris weighs six times the Savage, but only gets half the mileage. Put the opposite, the Savage weighs one sixth the Yaris but only gets double the mileage. Shouldn't it be more????

I'm no engineer, so I appeal to you who know far more than I to help me understand this. (Especially when I can't get my wrist to behave and get only 45mpg. ;))
Thanks

Title: Re: Why don't we get better MPG?
Post by mornhm on 07/23/08 at 05:24:57

It can probably mostly be explained by air resistance, a naked cruiser with a rider is not the smoothest shape (think raindrop) travelling through the air. My Concours with almost three times the HP gets over 40 mpg under exactly the same conditions that my Savage averaged 52 mpg - not fair to compare the Concours' overall mpg (44) to the Savage's because of several long trips on the Concours. As I said, under the same condition there's about a 20% difference, should be a lot more, but the Concours has a full fairing, the Savage was stock.

The rest of the explanation is just that MC manufacturers and buyers (US at least) in the past have not used gas mileage as a purchasing point. This is one of the reasons that you can't find a lot of the smaller engine models for sale in the US.

Title: Re: Why don't we get better MPG?
Post by Hutch on 07/23/08 at 05:54:24

I know what you mean about poor mileage on the Savage. I have a 120HP,1639 cc chopper that is not one bit aerodynamic, with a 45mm carb, weighs 550lbs, and it gets 50-55 MPG. To me that makes no sense what so ever. Hutch

Title: Re: Why don't we get better MPG?
Post by skrapiron on 07/23/08 at 05:56:44

Another consideration is the Savage is an entirely mechanical engine. Fuel delivery is done with vacuum pressure and metered by stationary flow jets. The Yaris is fuel injected, with an engine management computer. It can detect A/F ratios and adjust fuel metering to compensate, thus always maintaining optimal efficiency. The Savage's carb has to be manually tuned and cannot automatically compensate for barometric pressure, huidity, and temperature changes. What may be an optimal A/F ratio one day does not apply the next.

To be sure, getting 50+mpg is agood thing. Yes, you could get ALOT better with fuel injection (my C50 is delivering about 52mpg) but the additional cost and complexity would change the nature of Savage irrepairibly. It's a simple, inexpensive bike that just about anybody who remembers righty-tighty, lefty-loosey can maintain. My C50 requires a diagnostic computer and major disassembly to get to anything.

Title: Re: Why don't we get better MPG?
Post by bill67 on 07/23/08 at 06:25:08

The s40 would get a lot better if it weren't geared so low,turns more rpms then it needs to.

Title: Re: Why don't we get better MPG?
Post by T Mack 1 on 07/23/08 at 06:48:40

757E7B7B2120170 wrote:

The s40 would get a lot better if it weren't geared so low,turns more rpms then it needs to.

Agreed with Bill on this one. I really wish Suzuki would come out with a bolt on kit (new rear sprocket, maybe a belt and a speedo adapter) to get slightly better MPG.

Title: Re: Why don't we get better MPG?
Post by Jay on 07/23/08 at 06:48:52

All great answers, and I thank you.
mornhm,
I had not considered the aerodynamic differences to be a negative factor for the motorcycle. Your explanation makes perfect sense.

Hutch,
Hang on to that chopper, man. That's great MPG! Especially for that size engine.

skrapiron,
So it kinda makes it an unfair apples to oranges comparrison, doesn't it? I hadn't thought of weather beyond a headwind. It would, and does, wreak havoc with a carb. You're also right about changing anything on the bike, it wouldn't be a Savage anymore, and I couldn't love it like I do.

bill67,
See, that's the kind of thing I just never think of. I listened to my motor on the way home, became really aware of when I was changing gears, the subtle differences in RPM. It does tend to run more like a hummingbird, doesn't it? That would chew up gas!

WOW, thanks guys. It makes sense. Motorbikes could be changed to offer up more MPG, but they'd run the risk of not being motorbikes anymore, wouldn't they?

Title: Re: Why don't we get better MPG?
Post by thumperclone on 07/23/08 at 07:27:37

power to weight ratios??

Title: Re: Why don't we get better MPG?
Post by Gort on 07/23/08 at 09:26:00

If I remember correctly, resistance to air goes up by the square of the velocity of the moving object....IF I remember correctly. So you can see what the effects of aerodynamics has on MPG.

Title: Re: Why don't we get better MPG?
Post by 4carbcorvair on 07/23/08 at 09:33:18

Compared to the 16 mpg I was getting on the highway with my truck that I sold to get the bike, I'm LOVING the 65mpg I'm getting with the S40. :)

Title: Re: Why don't we get better MPG?
Post by buttgoat1 on 07/23/08 at 12:31:14

I think the sprocket ratio is the biggest factors because some folks have gotten much better at a 45-50 mph pace, I think I saw a claim of 70 here once. I wwould consider the chain conversion, but I do like the belt, an extra tooth up front and maybe 2 less out back would sure change things. A swoopy fairing would help problem #2, wind resistance. Fuel injection would only give a marginal mileage improvement, but would be far better for driveability. IMO.

Title: Re: Why don't we get better MPG?
Post by Keith_T on 07/23/08 at 13:00:12

Most bikes I've owned have gotten between 38 and 42 mpg regardless of engine config or size. My Savage gets 49 mpg most of the time. I'm happy enough with that.

Title: Re: Why don't we get better MPG?
Post by ChicagoRider on 07/23/08 at 19:19:57

I too have wondered why the Savage's MPG is so meager when compared to much heavier bikes.

Skrapiron's response about the lack of fuel injected/computer is right on the money. The antiquated carburetion is the main culprit.

Considering the Savage's low cost its no surpise its so bare bones. You pay for what you get.

I ain't complaining though, I ride my 2007 Savage to work daily and average 54MPG.

I burn only 2 gallons of gas a week, cost is $8 weekly, gotta love it. ;D

Title: Re: Why don't we get better MPG?
Post by SV og LS on 07/23/08 at 23:12:43

Most injected bikes get worse mpg than the carbed versions they replaced. They can be sorted however for better fuel economy.

Title: Re: Why don't we get better MPG?
Post by PerrydaSavage on 07/24/08 at 00:26:59

With my original '03 Savage, I got approx. 68-70mpg on a couple of Rides that were a steady hour to hour-and-a-half at 40-50mph ... haven't checked to see what my S40 is doing (yet) ...

Title: Re: Why don't we get better MPG?
Post by mick on 07/24/08 at 00:34:35

Like the old saying,when you are driving your car it's like watching a movie,when you ride you bike ,You are IN the movie.
we all tend to ride our bikes like we stole them (I know I do).
If you you eased your self away from the lights,slowly get yourself up to the limit (say 55) eased off the throttle a long way off the stop sign,
try to catch timed lights while in town,you will get at least 55 to the gallon

Title: Re: Why don't we get better MPG?
Post by Jay on 07/24/08 at 02:34:10

40444E4659454841444048542D0 wrote:

You're absolutely right, but where would the fun be in that? ;)
Seriously though, my mileage is all over the place. I average 50MPG, but tank to tank readings are as low as 38 and as high as 60. I know riding conditions effect mileage, and as my wife pointed out "Maybe the guy who's consistently getting 60MPG only weighs 150lbs." OUCH!
Still I wish I was more consistent in the MPG tank to tank.

Which reminds me. Have any of you experienced this? I run the tank til I need to switch to reserve. Then I run reserve maybe 5 miles and it sputters out. This has happened to me twice. Both times I was within feet of a gas station, so only a little pushing; but I'm not getting the 15 - 25 miles on reserve I thought I would be. When I hit reserve, I gotta find a fuel station quick. Did Suzuki short me on the length of my main tube so it's almost the same as my reserve? Guess I'll be pulling the tank and petc0ck next day off.

Title: Re: Why don't we get better MPG?
Post by klx650sm2002 on 07/24/08 at 03:45:07

KLX gets mid fifties (uk gallon), pretty good for a pumper carb.

Clive W :)

Title: Re: Why don't we get better MPG?
Post by barry68v10 on 07/24/08 at 04:09:14

[/quote]
You're absolutely right, but where would the fun be in that? ;)
Seriously though, my mileage is all over the place. I average 50MPG, but tank to tank readings are as low as 38 and as high as 60. I know riding conditions effect mileage, and as my wife pointed out "Maybe the guy who's consistently getting 60MPG only weighs 150lbs." OUCH!
Still I wish I was more consistent in the MPG tank to tank.

Which reminds me. Have any of you experienced this? I run the tank til I need to switch to reserve. Then I run reserve maybe 5 miles and it sputters out. This has happened to me twice. Both times I was within feet of a gas station, so only a little pushing; but I'm not getting the 15 - 25 miles on reserve I thought I would be. When I hit reserve, I gotta find a fuel station quick. Did Suzuki short me on the length of my main tube so it's almost the same as my reserve? Guess I'll be pulling the tank and petc0ck next day off.[/quote]

If you've ever disassembled the petcock, you'll begin to see why. The screen at the bottom of the RES side, only feeds the RES setting and not both. It's about 1/2" to 1" lower than the PRI/ON setting screen. (Which IS fed by both.) The screen will clog from the bottom up, so your RES screen gets plugged up first with debris and varnish. You should be able to remedy that by cleaning the screen. I could never drain my tank below about 1/2" of fuel, but then I removed the internal screen and replaced it with an external fuel filter. Now I can ride until my tank is BONE DRY. ;D (But I no longer have a "reserve tank".)

Sometimes that's a good thing....sometimes it's not. ;)

Title: Re: Why don't we get better MPG?
Post by sluggo on 07/24/08 at 10:58:25

why. because i ride with a two position throttle. wot. and closed.

Title: Re: Why don't we get better MPG?
Post by sjaskow on 07/24/08 at 11:12:45

I think a better way to think about it not our bikes get such bad mileage. It's that the Yaris doesn't get any better mileage than it does. When I was in college I drove a 1976 Corolla who's specs are roughly equivalent to the Yaris. It got a consistent 25 mpg in mostly city driving. It had a 2-barrel progressive carb, no engine mangement, etc and yet only got 4 or 5 worse mpg.

I wonder how good the Savage/S40 would be with a ODB-II fuel-injection system. :)

Title: Re: Why don't we get better MPG?
Post by Paladin. on 07/24/08 at 12:45:12

647D76647C7860170 wrote:

I...When I was in college I drove a 1976 Corolla who's specs are roughly equivalent to the Yaris. It got a consistent 25 mpg in mostly city driving. ...

In '70-72 I had a '67 Triumph Spitfire, 1300 cc, twin SU carbs. Drove like a madman, city streets with some freeway, consistently OVER 30 mpg. In fact, I monitored my MPG and would do a tune up when it did drop below 30. Got rid of the car after I tore the drivetrain a second time. (When you go airborne you really should get off the accelerator.)

Title: Re: Why don't we get better MPG?
Post by Paladin. on 07/24/08 at 12:48:08

When I went to visit Versalgen I filled up before and after. For the 70 miles freeway + 10 miles street I got 62 mpg.

Title: Re: Why don't we get better MPG?
Post by Jerry Eichenberger on 07/24/08 at 12:52:49

Understanding fuel consumption characteristics is beyond a simple posting.

Engines burn a mixture of air and fuel. So, how much fuel you burn to produce a given horsepower is a function of how much air/fuel is going thru the engine, the mixture setting (rich or lean) and the rpm of the engine.

For instance, in piston airplanes with constant speed props, you can increase power production by either increasing rpm, or what's called "manifold pressure", which is the amount for fuel/air being shoved thru the intake manifold, or by increasing both rpm and manifold pressure. Throttle controls manifold pressure in such an airplane.

Our bike and car engines don't have a way to control rpm independent of manifold pressure. So the only things we can do relate to throttle setting and mixture. We already know that the mixture on a Savage/S40 is too lean to begin with.

Hence, since throttle setting controls rpm, the only practical way to increase mileage is to reduce rpm. Remember that the engine is burning fuel each time the piston goes down on the power stroke, so we need to reduce the number of power strokes, or rpm, per mile.

You could do that by running at a slower engine speed by running at a slower vehicle speed. That's why the best mileage is obtained at the minimum speed to run in 5th gear effortlessly, without lugging.
But better, you could reduce rpm by going to higher gearing, so you get more rpm of the rear wheel, and hence more distance traveled, for a given engine rpm.

However, we all know that higher gearing results in poorer acceleration, so gearing ratios are a engineering design compromise (as every machine is) between the desire for acceleration, and efficient engine rpm at cruising speed. You can't have both at once.

To improve the mileage of any piston powered vehicle, just gear it up (assuming engine displacement remains constant). Since there is no free lunch, you'll pay for that with slower acceleration.

Title: Re: Why don't we get better MPG?
Post by Jay on 07/24/08 at 21:48:02

barry68v10
"If you've ever disassembled the petcock, you'll begin to see why. The screen at the bottom of the RES side, only feeds the RES setting and not both. It's about 1/2" to 1" lower than the PRI/ON setting screen. (Which IS fed by both.) The screen will clog from the bottom up, so your RES screen gets plugged up first with debris and varnish. You should be able to remedy that by cleaning the screen. I could never drain my tank below about 1/2" of fuel, but then I removed the internal screen and replaced it with an external fuel filter. Now I can ride until my tank is BONE DRY. (But I no longer have a "reserve tank".)

Sometimes that's a good thing....sometimes it's not."

Do you have pics? I'm not sure I could go without a reserve, but I would be interested in seeing what you've done. Thanks.

Title: Re: Why don't we get better MPG?
Post by Oldfeller on 07/25/08 at 03:23:21

I agree with Sluggo. The reason why I get poor gas mileage, used to have to change out a rear tire every other season and had to replace front brake pads frequently had to do with my right wrist and my liking going around corners fast. Accelerate hard, brake hard. It is a life-style choice.

Folks who ride 250 Ninjas in Europe have both versions available to them, injected and non-injected, and they ride street and track.

Guess what sort of gas mileage they get on the track --- 30-45 mpg. This is off a bike that CAN get nearly 90 mpg if ridden "sensibly".

Oldfeller

Title: Re: Why don't we get better MPG?
Post by PerrydaSavage on 07/25/08 at 11:47:02

OK, I just got home from work ... decided to gas up the S40 on the way to see what kinda milage she's turnin' ... this has been all commute Riding ... stop & go with a max speed of 45kph, with 1st thru 4th gears being employed, air temp in the low to mid. 70's since last gas up and roughly 500ft above sea level elevation where I commute (approx 20kms per day), stock factory settings on the carb and fuel/air mixture ... and I weigh approx. 140lbs

approx. 3.52 liters (0.93 US Gal.) of fuel for approx. 81kms (50mi) = approx. 53 mpg

Title: Re: Why don't we get better MPG?
Post by itschnobigdeal on 07/25/08 at 17:48:10

I think it's the fuel companies controlling vehicle production.

LOL!

One thing I've learned, I noticed it in a couple truck I owned and I've noticed it with bikes... If a vehicle has a "small" motor, but has to carry a heavy load it, it will have to work harder than the same vehicle with a larger motor. For example, I've owned two Dodge Rams, one a 318ci the other a 360ci. The 360 got 2mpg better, and i believe it's because it didn't have to work as hard as the 318 to power the truck along.
Another example, the reference to the 550lb 1700cc chopper... The 1700 V twin is probably barely idling (sarcasm) at highway speeds. If our 650 single was powering that bike I guarentee the bike would get worse mileage than it does with the 1700.
I've noticed the same thing when researching Kawasaki KLR models. The KLR 250 has almost 1/3 or whatever the displacement as the 650, but has to work that much harder than the 650 hence they get almost the same mpg.
I don't know if that makes sense, but it's something that I've kind of figured out over time. It seems like an equal tradeoff, and basically comes down to power to weight ratios. The Savage seems like it's right in the middle, not a ton of power/displacement, but not too little either. I'm happy with it and I think we all should be.

But seriously, I think it is the fuel companies. :P

Title: Re: Why don't we get better MPG?
Post by PerrydaSavage on 07/26/08 at 02:03:07

Edit to my fuel consumption post above ... max speed should've read 65 kph NOT 45 kph ... :-[

Title: Re: Why don't we get better MPG?
Post by PerrydaSavage on 07/26/08 at 18:36:50

Took a spin from St. John's to Carbonear, Nfld. (and back) to check out the annual Relic Riders MC Show n' Shine today ... combination of highway, and secondary coastal bi-way, very little stop n' go, speeds averaged 60-70kph on a guess ... gassed-up before leaving St. John's and again before returning from Carbonear ... 3.55 liters (0.94 US Gal.) for 101km (62.6mi) = 66.7 mpg! Not bad at all!

Title: Re: Why don't we get better MPG?
Post by Skid Mark on 07/26/08 at 19:02:35

I'm running a stock '08 with about 3,800km's on it. City riding is getting me around 60 mpg (50 mpg US gal.) and around 69 mpg (56 mpg US gal) on the Hi-Way. I'm about 190 lbs.

When you factor in vehicle cost, maintenance cost, ease of parking, and let's not forget the all important "Fun Factor", the Savage is a very good and cost effective set of wheels. :)