MPG is SUCK

[Rotten]

My 96 Royal Star with almost 30k miles on the clock. I replaced the stock filter with K&N, I went from the 4 into 4 exhaust to 4 into 2 with Road King cans. I've had the carbs out to clean and install new float needles, adjust the floats, and installed 1 size up in pilot jets. She also has the Vmax gearing, the carbs are synced and has no problems getting upto speed.

 

Im getting horrible fuel mileage, somewhere around 29 mpg. My old 97 Royal did better and she had 4x4 nasty boys and jetted and shimmed.

 

I did a compression test My dry numbers were

1 126

2 126

3 130

4 130

Wet with 2 squirts of tranny fluid

1 140

2 140

3 135

4 140

 

I used a tester from Harbor Freight, not sure how accurate it is, my brothers Snapon tester was shot.

 

Do I need to rejet for the air filter or the mufflers?

Would shimming the needles help or hurt MPG?

Does the Vmax gearing have a adverse effect on MPG?

[Yammer Dan]

V-Max rear would drop it some. Shimming needles could help.

[Flyinfool]

Either the K&N filters or the muffler changes or the V-Max rear each by themselves can reduce MPG.

What mileage were you getting before you made all these changes?

Even with these changes you still should be close to 40 MPG at 60MPH with no wind, at least in the high 30s.

 

High speed will kill MPG. I was down to 18 MPG driving at 80 into a 40 MPH head wind, pulling a trailer. As soon as I slowed to 65 and the wind died I was back to 40.

A good head wind or cross wind will drop MPG.

If MPG was calculated over just one fill and the first fill was not quite full but the send was a good fill it will look like low MPG.

 

There are a lot of variable that affect MPG.

We can help you sort thru them, best done one at a time because one change may help and another change might hurt and the result is no change. so you end up discarding a good change.

 

First is to see where you are at now.

After a good run at cruising speed, in a safe area, pull in the clutch, click off the kill switch and then stop off the road under no power. Pull the plugs and see if you are running rich or lean so you know what to adjust. Anything else is just trial and error guessing. Plugs should be a nice light tan color, darker is running rich and lighter is running lean. This will tell you if you need to jet up or down or add shims or remove shims.

 

Also just your riding style can have a big impact on MPG. Was this steady state cruising on the highway or city low speed stop and go? Was your right wrist having a good time?

[Rotten]

Ok, I bought that bike as a project. I replaced the exhaust to the bagger exhaust, added the filter as part of my reconditioning of the bike. So the MPG before I have no clue, Im just going by my last royal which was a 97.

 

Im swapping in stock gearing during my vacation in 2 weeks. Im not happy with the increased RPM of the vmax gearing

 

Ill do the test you describe soon. You say cruising like what a steady 55mph or 60 or speed doesnt matter ?

 

my riding style is usually conservative. After my 1st compression test, the oil I most of freed something up on the next day the ride to work was mostly at 5000 RPM. I have been known to get heavy on the throttle, but not too often.

[Flyinfool]

Cruising is at whatever your most common speed and RPM is.

 

When you said something loosened up..........

Another thing to check, are you running on all 4 cylinders? These bikes run amazingly well on 3 cyl but the MPG sucks.

There have been people that ran for years on 3 not noticing one was not working.

The quick test, when the bike is cold, start it up and monitor the header temps to see if they all heat up at the same rate, careful it don't take long to get hot enough to burn your finger.

[Guest divey]

Either the K&N filters or the muffler changes or the V-Max rear each by themselves can reduce MPG.

What mileage were you getting before you made all these changes?

Even with these changes you still should be close to 40 MPG at 60MPH with no wind, at least in the high 30s.

 

High speed will kill MPG. I was down to 18 MPG driving at 80 into a 40 MPH head wind, pulling a trailer. As soon as I slowed to 65 and the wind died I was back to 40.

A good head wind or cross wind will drop MPG.

If MPG was calculated over just one fill and the first fill was not quite full but the send was a good fill it will look like low MPG.

 

There are a lot of variable that affect MPG.

We can help you sort thru them, best done one at a time because one change may help and another change might hurt and the result is no change. so you end up discarding a good change.

 

First is to see where you are at now.

After a good run at cruising speed, in a safe area, pull in the clutch, click off the kill switch and then stop off the road under no power. Pull the plugs and see if you are running rich or lean so you know what to adjust. Anything else is just trial and error guessing. Plugs should be a nice light tan color, darker is running rich and lighter is running lean. This will tell you if you need to jet up or down or add shims or remove shims.

 

Also just your riding style can have a big impact on MPG. Was this steady state cruising on the highway or city low speed stop and go? Was your right wrist having a good time?

On the recent trip @Dale124 and I just got back from to the Dakota's, Wyoming and Montana, we fought headwinds and sidewinds every step of the way. I've always averaged between 46 and 48 mpg (imperial gallon) on long trips ever since I got the bike in 2007. This trip I got 36 mpg. I'm chaulking it up to the winds but will do the header test just to be sure. If it was only running on 3 cylinders, it's even a more impressive engine than I thought! Doug

[Rotten]

I meant to say, I think the oil I used on 1st compression test might have freed up a ring or 2.

 

Im looking into getting the valve clearance looked at. I dont think its smart to buy the tool and the shims, Im probably only doing this once.

swapping the Vmax gear to stock RS gears too

[camos]

You say cruising like what a steady 55mph or 60 or speed doesnt matter ?

 

... the ride to work was mostly at 5000 RPM. I have been known to get heavy on the throttle, but not too often.

Riding at 55 or 60 will get better mileage than riding at 70 or 80. Also, In my opinion 5000 RPM is not an economical choice. Somewhere around 3000 to 3500 RPMs would be a better choice.

[gggGary]

99 16K miles one person with a bunch of camping gear pretty much 40MPG, dips at speeds above 65MPH The BMW K1200LT with 130K on the clock would get 50 in the same conditions..... Advantage; Fuel injection.

[baylensman]

First let me say that so many things affect mileage. None more so than riding style and trip length!

I've owned an 86RSV , 96 RS and 2007RSV. Around town and short tripping (95) of my riding is below 60MPH) my MPG has never been higher than 36 or lower than 30. I've taken two long distance trips in the past two years (considerable time at 60+MPH) on both trips my MPG was 41.

 

Now I ride it like I stole it every day, all three bikes the same way. to and from work the store or whatever. Trips always required the van (kids and ex wife) Now that I'm paying off the divorce not a lot of trips under my belt yet. But 35 mpg and the wind in my face is much better that 14 mpg in the lincoln!

 

So as others have suggested to get a good baseline plan a trip somewhere out 120 miles or so Fill the bike prior to the leg out and again just prior to the way back. One way try and keep the needle steady and the rev's even the other way get a little more aggressive say 60 mph versus short sprints to 80+ passing and what not. This will give you a great idea of what the bike can get in MPG and what riding style does to it.

 

Plenty of MPG threads here refer to the Vacuum operated throats on these bikes and why keeping the revs higher helps. the bike should not ever see 5th gear unless you have a chance to run at 55 MPH or higher for a distance.(i've then mine to 80 in 4th without the bike screaming!)

[gggGary]

My FJR1300 previous Concours 14 and even the ZX14 all returned about 40 MPG on secondary roads at 60 ish MPG. An old KZ1300 manual stated 4000 RPM as the highest efficiency engine speed. I suspect this is true across a wide range of engines that redline at 8K ish and make some horsepower up high. Cam design is always a compromise, and a high horsepower cam will not get good fuel efficiency when lugged at low RPM. My XS650s get 50 MPG, so even huge reductions in mass, profile and power do relatively little to improve mileage. The honda 700 parallel twins (CTX700) are supposed to capable of 70MPG and I am thinking along those lines when I find the right deal on one.

[baylensman]

So my wife was out of town for a week. I used her car almost every day due to weather and having to run errands after work( remember she's out of town so I had groceries and the vet and what not). Her milage computer in the dash started the week at avg 16.1 MPG now this is an SUV (Ford Freestyle) used for around town, both of us work fairly close to home so no longer trips. Well anyhow end of the week the trip meter now shows 17MPG average! I guess she's a little more aggressive behind the wheel than I am! So in just a week i've increased the avg by 1 mpg, doesn't seem like much until you consider the trip computer was last reset 5000 miles ago and i only put on about 200 of those, so my actually MPG was probably much higher. Just to show what driving/riding style can do to MPG. Now if I can just do that on two wheels HAHAHHAHAHA

Edited July 5, 2017 by baylensman

[gggGary]

Speed KILLS (fuel mileage) road trip at 60-79 reserve at 180 miles Hammer down at 80MPH no headwinds reserve at 130 miles. G3 stock windshield from last years riding a short bagger shield windshield was worth near 5MPG But I didn't think it was worth the much louder and more turbulent ride. Or rain intrusion.

[Flyinfool]

So my wife was out of town for a week. I used her car almost every day due to weather and having to run errands after work( remember she's out of town so I had groceries and the vet and what not). Her milage computer in the dash started the week at avg 16.1 MPG now this is an SUV (Ford Freestyle) used for around town, both of us work fairly close to home so no longer trips. Well anyhow end of the week the trip meter now shows 17MPG average! I guess she's a little more aggressive behind the wheel than I am! So in just a week i've increased the avg by 1 mpg, doesn't seem like much until you consider the trip computer was last reset 5000 miles ago and i only put on about 200 of those, so my actually MPG was probably much higher. Just to show what driving/riding style can do to MPG. Now if I can just do that on two wheels HAHAHHAHAHA

 

I see the same thing on my wife's Chevy Trax. She gets 25.8 MPG and I thought I was playing with the turbo a lot and I get 35.2 MPG. That is a HUGE difference due to only driving style. With her driving it is only her in the car. When I drive it, there is her, the 90 lb dog, and me in the car. So on paper I should be getting less MPG due to an extra 325lbs in the car.

 

As I posted earlier, I have gotten anywhere from 18 to 45 MPG on my bike just due to riding style and weather conditions, actually got both extremes on the same day.