Running lean / Gas mileage

[The Snowman]

I've read quite a few threads on different bike forums about how modern sport bikes get somewhere between 30 - 40mpg average.

My 97 CBR900RR gets anywhere between 42 - 48mpg. Someone suggested that it's most likely because it's running lean.

Well, I purchased it used and it already had a Two Brothers full exhaust & K&N stage 1 kit installed.

Could the former owner have installed jets that make the bike run too lean? If so, what good/bad does this do? Would it contribute to my header popping? Is this something I should be worried about?

[stoinkythepig]

I suspect your choice of roads and riding style will affect MPG quite a bit. My completely stock 2001 ZX9R gets 43-44 MPG routinely.

[Tabby]

A couple of quick questions. Are you still riding it now? If so, does it take forever and a day to warmup? If it doesn't, then it probably isn't too lean. You probably are just a conservative driver, when you aren't playing around, and that isn't a bad thing.
My heavily modded 86 gixxer gets 48 mpg commuting to work, and about 20 mpg out on the track.

[The Snowman]

Originally posted by Tabby
A couple of quick questions. Are you still riding it now? If so, does it take forever and a day to warmup? If it doesn't, then it probably isn't too lean. You probably are just a conservative driver, when you aren't playing around, and that isn't a bad thing.
My heavily modded 86 gixxer gets 48 mpg commuting to work, and about 20 mpg out on the track.

No, it warms up just fine. I ride it hard when I'm in the twisties, but nearly as hard as you would at the track. The worst mileage I've see so far has been 42mpg.

I guess the bike is just good on gas.

[Tabby]

Gotta love modern bike engines! All that power and gas mileage too! Car guys can eat their hearts out. Especially the dudes with the older muscle cars.

[KB]

My Superhawk gets about 30mpg. It's a gas hog. But then again I don't ride it easy or slow.

KB

[TheIglu]

My KLR gets about 70mpg jetted Stage 1 Dynojet. Then again I don't ride it easy or slow.

Leave your jetting alone. If it's not burning up spark plugs or overheating regularly, it ain't running lean.

[Billy]

my 99 CBR 600 F4 got about 35 mpg with a stage 1 jet kit. I road it semi hard.

[richw]

Lean is clean not efficient

Purpose of lean jetting is lower hydrocarbon emissions.

Slightly richer will improve efficiency and raise gas mileage. Stock jetting is too lean at up to 1/4 throttle then good on large throttle opening (main jet) where EPA does not test.

A stage1 should should improve gas mileage and throttle response.

My stocker Gixer on super cruise 70 but few full throttle passes will return 44 to 47 MPH. In north Vermont that drops to about 35

Be Happy

[RGVER]

To be sure just check the color of your plugs

[MsHap]

Originally posted by RGVER
To be sure just check the color of your plugs

+1

[The Snowman]

Originally posted by RGVER
To be sure just check the color of your plugs

Well, I just replaced them and the old ones were a little brown. Definitely not running rich.

[R7]

Big bore inline bikes are pretty much always better on gas the the 600s. I used to get 50mpg with my 04 R1 on a easy commute to work. Same commute on the 06 R6 was 38mpg.
Though the same commute again on a 06 KTM 525 Motard got 65mpg

[ZX-12R]

My 12R averages 30mpg. When taking it easy, I can sometimes get 38mpg. On one ride in NH I went 44 miles and took 2 gallons bringing my low down to 22mpg!

My SV650 gets 42mpg when I ride it and about 54mpg when my lady rides it.

[benVFR]

Ethanol is sucking up a couple of mpg versus last year.

The dealership had a big warning at the service counter about lots of carbed bikes having issues with E10 gas.

If you have any residue, varnish, gunk, etc.. in your fuel tank or fuel system the ethanol in E10 will break it free and it will travel through till it clogs something.

Once it's all cleaned out and running on Ethanol it should stay cleaner though.

[The Snowman]

Originally posted by benVFR
Ethanol is sucking up a couple of mpg versus last year.

The dealership had a big warning at the service counter about lots of carbed bikes having issues with E10 gas.

If you have any residue, varnish, gunk, etc.. in your fuel tank or fuel system the ethanol in E10 will break it free and it will travel through till it clogs something.

Once it's all cleaned out and running on Ethanol it should stay cleaner though.

Whew. I haven't experienced any issues with E10 and I've probably pumped roughly 100 or so gallons through my carbs.

[ZX-12R]

Originally posted by benVFR
If you have any residue, varnish, gunk, etc.. in your fuel tank or fuel system the ethanol in E10 will break it free and it will travel through till it clogs something.

That's probably why the fuel pump in my 12R is acting up.