2006 RSTD Poor Fuel Mileage - Suggestions

[1fastbob]

I have a new to me 2006 RSTD with 16,750 miles that is getting 30 mpg when hand calculated using 87 octane E-10 fuel. Fuel mileage is actually 27 mpg when I figure in the 10% odometer error. Bike is stock and has Bubs mufflers. Air cleaner was just serviced (cleaned) by ASE certified tech (I haven't verified that yet). Right rear spark plug looks good, but maybe a little towards the rich side (deep brown and not wet). Starts easily in the morning without choke and seems to run pretty smooth. I live in South Central Kansas and have been riding it to work which is 15 miles 2 lane and 4 lane highway with 2 stops. Terrain is mostly flat and I ride 70 mph in traffic and 60 to 65 when not being pushed. I am easy on the throttle and have been riding on and off for 44 years.Any suggestions on what to look at regarding this poor mileage? Carb sync? Plugs? Air Filters? Carbs? I really think it should get between 36 and 41 mpg from the reading I have been doing. I get about 100 miles before the low fuel indication comes on.

 

Thanks in advance for the help.

 

Bob

[spike13]

i am no expert but if i was you i would be looking at the choke linkage perhaps a spring is missing or broken or a pin just guessing might wanna check float levels maybe one or more is sticking dis the bike sit for a long period?

[jfoster]

On my '06 rstd 32-37 mpg was the norm on e10. Some say it maybe only running on three cylinders and that rear are most likely to fail (coils).

[1fastbob]

i am no expert but if i was you i would be looking at the choke linkage perhaps a spring is missing or broken or a pin just guessing might wanna check float levels maybe one or more is sticking dis the bike sit for a long period?

Bike could have sat for awhile. Not sure. I gave it a 10 ounce Seafoam in 3 gal. of gas treatment, rode it a couple of miles and let it soak for a couple of days and noticed no difference.

 

Thanks

[1fastbob]

On my '06 rstd 32-37 mpg was the norm on e10. Some say it maybe only running on three cylinders and that rear are most likely to fail (coils).

I will check for spark at all cylinders and change the plugs.

 

Thanks

[Bones]

New to you and has aftermarket exhaust. I wonder if the bike has been re-jetted rather poorly actually... Just a thought.

[1fastbob]

New to you and has aftermarket exhaust. I wonder if the bike has been re-jetted rather poorly actually... Just a thought.

That thought has occurred to me. If everything else checks out I may have to yank the carbs and check the jets.

 

Thanks

[MikeWa]

Bob

It is rare to have to re-jet these for an exhaust swap. Air and exhaust is another story. While your mileage is low it may not be to far out of line. Several of us around here have noticed a severe fall off in fuel mileage with this years winter blend of gas. My RSV fell from 45 to about 32 mpg. While my friends 2012 Harley Ultra dropped from 44 to about 35 mpg. Granted Washington is a long ways away but something is going on with the gas.

 

Mike

[dave_wells]

My 06 RSTD New 160 miles to reserve

 

 

That was short lived I have 52,000 on it now

no one has been able to figure out the mystery of low MPG

Highway speeds are very poor back roads a little better

Still 30 mpg if I'm lucky

25 mpg pulling a trailer

 

Almost the same mileage as my 96 Jimmy

Not Stayin much

 

 

Synced carbs / new plugs / sea foam / fuel filter / air filters / spark plugs /

Tire pressure / regular oil changes

 

The only thing I changed

I am running Metzler tires

Running these same tires on my venture with great Mpg

The RSTD is due for tires so I may try something else and see what changes

 

 

Checked for air leaks

Got some opinions from members

2 dealers and no input

Only thing I have not done is carb rebuild

 

Figure it out pass it on

 

Dave ....

[Wade 2000]

My Buddy has a RSTD with 60k on it and he consistently tears me up on mileage. If I get 42 he gets 45 on the same trip, same roads, same gas, and generally same riding style. The only difference I know of is he had his carbs rebuilt.

35mpg is unacceptable on this bike. I have a 2000 RSV and even with 2up riding and full luggage at 75+mph I can get 38-39, solo is 42 all day long, every day.

[1fastbob]

Bob

It is rare to have to re-jet these for an exhaust swap. Air and exhaust is another story. While your mileage is low it may not be to far out of line. Several of us around here have noticed a severe fall off in fuel mileage with this years winter blend of gas. My RSV fell from 45 to about 32 mpg. While my friends 2012 Harley Ultra dropped from 44 to about 35 mpg. Granted Washington is a long ways away but something is going on with the gas.

 

Mike

Winter grade fuel is long gone here. I buy the same fuel I put in the Roadliner I had. I could get 40 mpg out of the Roadliner, what a beast. It has to be something related to intake, spark, exhaust or something else. Valves don't require adjustment till 26,000 miles, but maybe that is the problem. I think I will check the easy stuff first, like the air cleaner, change plugs and sync the carbs. Might be a week or 2 before I get started, but I will report back here. I am persistent and I will find the cause.

 

Thanks

[Galapagos]

On my '06 rstd 32-37 mpg was the norm on e10. Some say it maybe only running on three cylinders and that rear are most likely to fail (coils).

 

I would think you would feel that missing cylinder as a miss or a vibration.

[MikeWa]

My 06 RSTD New 160 miles to reserve

 

 

That was short lived I have 52,000 on it now

no one has been able to figure out the mystery of low MPG

Highway speeds are very poor back roads a little better

Still 30 mpg if I'm lucky

25 mpg pulling a trailer

 

Almost the same mileage as my 96 Jimmy

Not Stayin much

 

 

Synced carbs / new plugs / sea foam / fuel filter / air filters / spark plugs /

Tire pressure / regular oil changes

 

The only thing I changed

I am running Metzler tires

Running these same tires on my venture with great Mpg

The RSTD is due for tires so I may try something else and see what changes

 

 

Checked for air leaks

Got some opinions from members

2 dealers and no input

Only thing I have not done is carb rebuild

 

Figure it out pass it on

 

Dave ....

 

 

See if you can find a mechanic with an emission analyzer. And the knowledge of how to use it. Ask them to check your HC and CO readings. If they can do this on a dyno it is even better. This will aften help detect the cause of an otherwise undetectable problem.

 

Mike

[djh3]

Starts easily in the morning without choke and seems to run pretty smooth.

Bells-Whistles go off Blink Blink:::::

Tells me its rich to start with. I agree with the feloow recomending looking into the choke system. Linkage sticky, choke partially closed or maybe a bad (leaky) diaphram or something in the choke system.

[1fastbob]

Bells-Whistles go off Blink Blink:::::

Tells me its rich to start with. I agree with the feloow recomending looking into the choke system. Linkage sticky, choke partially closed or maybe a bad (leaky) diaphram or something in the choke system.

Does your Venture require the choke when the temperature outside is 50 to 70 degrees during a cold start? If so, that might be the place to look.

 

Thanks

[dkip]

I have a 2006 RSTD and the mpg drop like yours did and the bike still ran fine just a lot more gas

It was a bad coil. If you have not checked the coils yet I would try that first. You can just warm up the bike and feel the pipes to see if they all get hot On mine one pipe never got warm.

It is worth a try if you have not eliminated the coils as a problem yet

dale

[1fastbob]

I have a 2006 RSTD and the mpg drop like yours did and the bike still ran fine just a lot more gas

It was a bad coil. If you have not checked the coils yet I would try that first. You can just warm up the bike and feel the pipes to see if they all get hot On mine one pipe never got warm.

It is worth a try if you have not eliminated the coils as a problem yet

dale

I have an infrared thermometer and try that right now. I'll report back.

 

Thanks

[1fastbob]

All cylinders are firing. I think I'll run to town and p/u a set of plugs later today. I had only previously pulled the right rear and looked at it. Condition and color of plugs will tell me a lot. Bike does smell a little gassey while running in the garage and engaging the choke while it is a idle kills the engine so the choke is at least somewhat properly working. Anybody know if the RSTD uses an actual choke or an enrichment circuit? My guess is enrichment circuit in the carbs.

[RSTDdog]

Yes enrichment circuit. each carb has one connected with linkgage to the choke knob.

[KICKSHOT]

My 05 RSTD never got good gas mileage. I am not one for checking it often. 33-35 was all I ever noticed from it. I have noticed from reading on here that mileage reports are all over the place. Many things effect it also. Like making sure that you fill your tank to the exact same spot every time. Very hard to do and when you are talking about a five gallon volume well there's plenty of room for error.

kickshot

[Blarg]

In my experience, the most common reason for consistently low mileage is a sticky choke. It makes the bike run rich, and that richness is extra unburned fuel that's just going out the exhaust. If it has that gasoline smell while it's running, that's generally the issue. It's starving for air. Check the choke cable and linkage to make sure it's not sticking, and you might even want to pop out the carbs and make sure it's all working right.

[RSTDdog]

My 06 RSTD New 160 miles to reserve

 

 

That was short lived I have 52,000 on it now

no one has been able to figure out the mystery of low MPG

Highway speeds are very poor back roads a little better

Still 30 mpg if I'm lucky

25 mpg pulling a trailer

 

Almost the same mileage as my 96 Jimmy

Not Stayin much

 

 

Synced carbs / new plugs / sea foam / fuel filter / air filters / spark plugs /

Tire pressure / regular oil changes

 

The only thing I changed

I am running Metzler tires

Running these same tires on my venture with great Mpg

The RSTD is due for tires so I may try something else and see what changes

 

 

Checked for air leaks

Got some opinions from members

2 dealers and no input

Only thing I have not done is carb rebuild

 

Figure it out pass it on

 

Dave ....

 

One thing I see missing from you list is valve adjustment. 52,000 miles you would be due your 2nd valve adjustment. 1st one was due at 26,000. Something else to check if it hasn't been done.

[Squidley]

I'll toss this in fwiw...

 

I had one of the Houston crews '05 RSTD while he was in Joplin MO with FEMA. He wanted me to ride his bike to keep it up and I did just that. I rode it every day and performed all the maintenance on it for 6 months. It never got good mileage, ever. It was synced properly and the bike ran great, lots of power. I have always wondered why it never got as good mileage as say an RSV or even a 1st gen which is usually in the upper 30's low 40's. The bike at best would get 35 and 32 was the norm. It might just be the nature of the beast with the RSTD's

[dluedke]

My 2008 rstd has alway got 32mpg and 35with the wind to my back and down hill. It runs great and has lots of power. I have checked coils, synced carbs, set float levels, changed plugs several times,tryed fuel aditives you name it even running in 4th gear to get in the power band but its alway 32 mpg. Thats about 130 miles to reserve and another 40 or so for a total tank milage of 168.