Extremely poor fuel mileage on 04 Rockster; 50 miles before warning light

Hi all,

Ive read up on the other posts and people were complaining about having mileage in the high 30s. Im getting about 20. Had the throttle body synched professionally. The exhaust does smell rich.

Bike does not have a catalytic converter and has custom exhausts. Removed vapor canister and checked stick coils.

What could be causing such extremely bad fuel economy?

Thank you

I should add that it's all stop and go city driving. Splitting lanes, accelerating hard from stop lights, etc. Also brakes are not sticking.

Try riding gently and see what you get?

Hi all,

 

Ive read up on the other posts and people were complaining about having mileage in the high 30s. Im getting about 20. Had the throttle body synched professionally. The exhaust does smell rich.

 

Bike does not have a catalytic converter and has custom exhausts. Removed vapor canister and checked stick coils.

 

What could be causing such extremely bad fuel economy?

Morning Imgnr

If the bike otherwise runs OK then maybe it is not doing as bad as you think-- How accurate is your odometer? Have you checked it against a known & measured mile?

If it is in fact recording correct miles traveled then the city riding sure isn't helping (you are getting ZERO miles to the gallon when sitting still at a light or sitting in stopped traffic with engine running). (what mileage do you get at a steady 65 mph out in the country?)

Otherwise-- things like fuel leaks, failing o2 sensor, incorrect spark timing, incorrect CCP, excess fuel pressure, engine sensor problems, etc can all effect fuel mileage.

20 mpg sounds real low for an 04 Rockster no matter how you ride it so verify that the odometer is accurate before doing anything else.

Dirtrider - I still have not had a chance to take the bike on a long ride. It was sitting for at least three years (probably more). Its probably a good idea to wring her out.

For comparison...I recently picked up an '04 Rockster and before putting it on the lift for a input spline inspection and lube... which revealed typical spline failure (grrrrr) I was getting about 38 mpg on the hgwy. The Rock has the sport g'box with a slightly shorter 6th gear so revs will be higher at speed.

Imgnr,

Could it be the fuel level sensor misbehaving?? Mine started giving me a warning at about 50 miles several months ago. Wasn't real bright, but got my attention. Now I just use the trip odometer. This '99 R1100S will get exactly 158 miles per tank. !!

Lowndes,

I filled up last night; over 4 gallons on 60 miles in the odometer. The odometer is accurate. Its a gps odometer.

This is a new to me bike that i rescued from being junked. Will go for a long ride on the freeway to see see it itll help. Been doing only city riding.

Thanks for the benchmark. Sorry to hear about the spline. Have not checked mine. Keeping fingers crossed. I read somewhere that yiu can lube it with a long needle wo having to take the bike apart.

"... 4 gallons on 60 miles..." sounds like a fuel leak. Don't know if I could MAKE mine do that.

What color are the pipes??

Lowndes,

 

I filled up last night; over 4 gallons on 60 miles in the odometer

Check for a restriction in the air intake path. If the bike had a choke I'd say it was stuck. Is it blowing black smoke out the exhaust?... has to be.

My year-04 Rockster does a regular unwavering 48 mpg but that's UK gallons, 'cos the bike is in the UK and I can't change the display to kms.

Like I can on my lovely Spanish Honda NC750S-DCT, the 6-speed auto-tranny steed that's the best and most enjoyable ride I've had in 40 years' of biking. No need for a complete headlamp conversion between EU & UK 'cos the lamp dips vertically, not sideways. Display is alterable between gallons/mpg and liters/kms per liter at the touch of four buttons.

And I get around 75 to 85 mpg out of the little angel. And it's almost as pokey as the Rockster. And better finished and more durable...

Try one - altho' the US has only the 700cc not the much better 750 version for some Trumpish reason.

You'll never ride a BMW bike again once you've tried a Honda Auto.

For example, in the US, would you ever order a new car with MANUAL transmission ? No, never.

 

For example, in the US, would you ever order a new car with MANUAL transmission ? No, never.

Don't throw us all under the bus, Alan. Some of us do still have Manual transmission cars. And I wouldn't ride a bike with an Auto unless I was physically unable to shift.

Try one - altho' the US has only the 700cc not the much better 750 version for some Trumpish reason.

Educate yourself. Leading theory is that Honda didn't want to incur the expense of EPA certification of another engine design, hardly a Trumpish reason. Good business decision as a discerning US market wouldn't pay a premium for an additional 3 hp. Enjoy your 3 hp.

In before the surprisingly slow lock.

Okay, I lied. The top / main plugs were not sparking. Both of them. I took the mechanic's word that they were. When I unplugged the bottom plugs on either side, the engine would die. This tells me that neither of the top plugs were sparking.

I bought new (used) coil sticks from E-Bay and neither of them made a difference. I know some of you might say they're bad but I don't think all FOUR sticks could be bad.

What would cause the top sparks from not sparking? What should I check first?

Going on a ride in two weeks and would like to get this figured out.

Thank you again all!

There is a green wire at each stick coil. With the key on you should measure about 12.5V.

Does your bike have a second load relay. If it does it will be located to the left of the Coding Plug. Post a photo of your electrical box and we can let you know.

 

For example, in the US, would you ever order a new car with MANUAL transmission ? No, never.

 

Don't throw us all under the bus, Alan. Some of us do still have Manual transmission cars. And I wouldn't ride a bike with an Auto unless I was physically unable to shift.

Ditto.... I want to shift my gears......period.

For example, in the US, would you ever order a new car with MANUAL transmission ? No, never.

I would, but they're getting really hard to find...

For example, in the US, would you ever order a new car with MANUAL transmission ? No, never.

 

I would, but they're getting really hard to find...

You can barely find a Mini Cooper with a manual transmission any more. It's kind of sad.

For example, in the US, would you ever order a new car with MANUAL transmission ? No, never.

 

I would, but they're getting really hard to find...

My sentiments EXACTLY. I most certainly would order a new car with a manual transmission if I could. I've held onto a '96 4-Runner and a Corolla for just that reason...well that and three kids in college. All those kids learned to drive a manual, and that skill even helped one of 'em get a fun side job this summer, driving an old VW bus retro-fitted as a photo booth for parties.

I've driven a few paddle-shift cars, but really miss the ability to quickly disengage the tranny. Just feels like I have way more control with a clutch.