Fuel Economy - what am I missing?

[jclanin]

Hi all,

I'm new to this bike & forum...very happy with both.

I am perplexed however... I'm not getting near the fuel efficiency I would assume for this bike.

- I fill up completely - 93 octane - city driving
- Fuel light comes on at about 115 miles

- 5.4 gallon tank
- 1.3 of that is reserve

So, I'm getting 115 miles on 4.1 gallons of gas = 28mpg.... correct? I thought I would get around 40mpg in the city. Thoughts?

thanks,

JC

[Arbreacames]

First make sure that you are indeed putting 4.1 gals. If you are not squeezing in the last drop of fuel or if the light comes on a little early, we may be talking about, say, 3.7 gals (31 mpg).
Secondly, all bets are off when talking about city riding. Is it Big Apple-type commuting, or more like Lexington, KY?

[Airman]

You should be getting something like 38 mpg in town. You can't calculate it from that fuel light however. Next time when the fuel light comes on, go in and top the tank again and see how much you use. I'm thinking your fuel light is coming on early.

[rdsmith3]

My fuel light comes on similar to yours, maybe at about 125 miles. But it is very unreliable.

So when I commute, I have to fill up every day. It is about 110 miles round trip, and it generally takes about 2.8 gallons. That gives me about 39 mpg for some stop and go traffic and a lot of highway riding.

The moral of the story is, you cannot go by the fuel light -- you have to use the actual gallons you put in the tank.

[brem]

I think your numbers are right, unfortunately. I regularly do full tanks of Chicago city commuting and get ~110 miles to 4.1 or 4.2 gallons of gas. The difference between being light on the throttle or being really ham-fisted changes that from around 120 at best to 95 at worst, so clearly the bike just doesn't get awesome mileage while sitting in traffic and moving sporadically at speeds under 25 mph. It clearly is capable of getting good mileage though, because on road trips I've gotten 45mpg with 350lbs of people and full luggage and near 50 when it's just me. All I can think of is that it doesn't burn fuel as thoroughly as a four-cylinder bike, at least at idle or very low speed.

[jclanin]

Thanks for the replies - they help a great deal regarding my sanity...

I'm about to order a Remus exhaust kit and K&N filter - probably won't help from an efficiency stand point... But it'll be fun!

JC

[wncbmw]

Fuel lights are not reliable and can come on at different levels for different bikes. Recently while traveling with a board member on an identical bike to the Bash, we found out my fuel light came on way before his but when we filled up, we were getting identical mileage!

I then got brave and nearly ran out of gas but that is another story!

[CycleRob]

It's a big twin, fuel injected engine but it has really tall gearing, giving it the capability to get decent fuel economy. Idling in traffic and repeatedly running it in the lower gears do bad things to fuel economy. If all you're doing is city driving, you won't see any sustained steady 6th gear and the MPG is going to be really terrible. It needs to see 6th gear and a steady 65---70MPH for about 2.5 hours. You'll break 50 MPG under those conditions.

It's mostly about the type of riding you do. In the first ~3 years owning my bike that I kept track of the MPG, in 88 fill-ups it never got below 41.9 (in winter) with a highest of (really trying) 56.5 MPG. The number that appeared most often then (and now) was 48. To be fair, the 56.5 MPG was achieved with the ignition timing advanced 3 degrees using Premium fuel. Now I use Regular gas and the stock TDC static setting. Still getting at least 48.

.

[Ves]

I've been doing some commuting lately. I was also disappointed... 38 mpg... Geeeessss my 3000 lb car gets about 30...

[rdsmith3]

Last night's fill up was 120 miles and 2.83 gallons, or 42.4 mpg for some stop-and-go and a lot of highway commuting.

One thing that troubles me, though, is that in the summer I have to run premium. With the middle grade, when I hit the throttle hard, I will sometimes hear knocking. This problem goes away with premium.

[challey]

Bob said:

One thing that troubles me, though, is that in the summer I have to run premium. With the middle grade, when I hit the throttle hard, I will sometimes hear knocking. This problem goes away with premium.

I've experienced the same thing and also need to use use premium in the hot weather or I'll get some knocking below 3k. My mileage is in the high-30's range around town, so the $'s add up quickly. On the brighter side, what Cycle Rob said about highway mileage is also true: I get 50+ mpg on sustained slab rides.

Charlie

[Boris Badenov]

when riding in NYC I'm getting around 30MPG (mostly 3rd and 4th gear) so your numbers are right there. On a highway its about 45 though.

[Croc]

No one's mentioned tyre pressures. It's important to check the pressure regularly as lower pressures will increase consumption. I try and keep my Z6s at 36 front and 42 rear.
When commuting my light always comes on at 160 - 165 miles. On the slab I have had just over 200 miles before the light. still rode another 36 before getting to the gas station!!!

Croc

[KHaynes]

I regularly get 34 mpg (that's US gallon) from my RT. These are results from a daily 8 mile commute to work.
On a long freeway run, I get in excess of 50 mpg at a sustained speed of just under 70 mph.
*** I've rounded all the numbers after metric conversions.

[sweatmark]

Rockster MPG
2004 R1150R Rockster, loaded for camping
odo net gallons mpg
12486 n/a 4.18 n/a
12653 167.0 4.247 39.3
12702 49.0 1.158 42.3
12870 168.0 3.913 42.9
13027 157.0 3.916 40.1

This is from last weekend's ride. Note that Rockster has short 6th gear, speeds were moderately high, and last leg calculated included 20+MPH headwind over 2.5 hour duration.

[spoolyg]

Posting my first...

I just bought my 2003 2 months ago, from a guy who took immaculate care of it. I have fallen madly into love for the 4th time in my life, the 1st time with a bike. About to check out of everyday life for a month, riding from NYC to Ariz, Mont and back with my brother. I had gently tried to nudge him this way, but he seems set on a used HD Road King. At least we will have extra storage space.

I have been estimating about 30 mph driving mainly around NYC, down the West Side highway, etc. Looking forward to stretching its legs.

I have enjoyed this forum for the past week since I found it. Glad to be part of the chatter and the community.

Spoolyg