Significant drop in gas mileage

[Chuck35]

Does the FJR have an ambient air temp sensor for the fuel system?

If so this would account for a drop in MPG during the winter months.

 

[RaYzerman19]

I would think 48 mpgUS is unusually good, I average around 40-43. One other thing to check, is the bike coming up to 4 bars temperature (3-4 in freezing temperatures)? A partially sticking open thermostat will affect that, but I think FJR thermostat issues are rare.

 

[RossKean]

I've been getting great winter mileage. Managed 10,000 miles per gallon the other day. (Rolled the bike around the shop - engine off) The "consumption" was evaporation when I popped open the gas cap.

Seriously, I see a significant mileage drop in late fall/early spring. Several reasons... Winter gas blend (higher volatiles such as butane). More frequent stops/shorter rides. Higher proportion of "in town" riding. Higher proportion of ride is in the "warm up" stage - very poor mileage until the engine comes up to temperature.

 

[sath182]

Did you change the type/brand of tire on your rear? If the profile is actually taller it would make a difference too. My SV saw a 4% decrease switching from the stock D220s to PR3s with the "same" size. But that's also a front wheel sensor. Just my 2 cents.

 

[blueman]

I recently freaked out when I fired up my bike and I was riding and noticed I had about 80 miles on the trip meter and showing a quarter tank of fuel. I went to fill it up and took 4 gallons . What, am I getting 20 miles a gallon, I always fill up , always! The bike runs perfect. Then I remembered I installed a new battery about 80 miles back. Wow Mam.

 

[odot]

It's a tire pressure thing....that and the pumpkin oil has never been changed and it's thick as mollasses.

 

[Bounce]

Molasses pumkin. Yum! I like pie.

 

[Eric L]

For sure my mileage drops when the bike is cold (and its cold outside. Mileage also drops when my f*cking rear brake is dragginh for 3000 miles.

 

[odot]

You should have gotten an abs light before 3000 miles.

 

[Goodman4]

If I were you I would try this: Put the FJR on the centerstand and spin the rear wheel. With a hard spin it should go several revolutions before stopping. Then have someone push the rear down raising the front. Do the same to the front wheel. It should have the same result. If so, you are good to go there.

Skooter, sorry for the late response, but I just now had time to check the spin. I was kind of concerned and surprised by the result. I spin the back pretty hard and it feels kind of like it's rubbing, going around only a little more than one revolution. But the front feels even worse and it doesn't even make it around a full spin. They only replaced the back tire when the mileage dropped. I would have thought I would have got an ABS light if it was rubbing a lot.

 

[RossKean]

Take the brake calipers off and do the spin thing again. If it still doesn't spin freely, you need to look at bearings. If it spins OK, then you may have an issue with either a sticky rear brake pedal pivot (which can also affect the front brake due to the linked brake feature) or with pistons/brake seal issues. Would look at the brake pedal first. (Note: you might try lifting the brake pedal first and see if that frees things up before removing the calipers to do the test)

 

[mcatrophy]

... a sticky rear brake pedal pivot (which can also affect the front brake due to the linked brake feature) ...

Just to be pedantic, it's unlikely that a sticking rear brake lever would activate the front calliper. There is a threshold rear brake force required before the front activates. If that amount of force was in play, I'd expect significant other symptoms, like a smoking rear brake

.

 

[RossKean]

... a sticky rear brake pedal pivot (which can also affect the front brake due to the linked brake feature) ...

Just to be pedantic, it's unlikely that a sticking rear brake lever would activate the front calliper. There is a threshold rear brake force required before the front activates. If that amount of force was in play, I'd expect significant other symptoms, like a smoking rear brake

.

I agree. Just the easiest thing to check and while it isn't very likely to have a large affect on the front, it is the most likely issue for the rear brake. Worth checking in any case.

 

[Bounce]

Yeah. Check easy things before diving in with disassemblies. One thing I started doing with the Wings was pulling the calipers and R&R the brake pistons; cleaning them up with brake cleaner and a scotch bright, cleaning the dust boots, and reassembling them. I'd do this every time I was doing a brake fluid flush (every 2 years) just to keep track of when it was last done.

Garage DIY stuff that's worth the effort.

 

[Goodman4]

Thanks again for all the advice. I took it by the Yamaha dealer this afternoon just to get someone's opinion that could see and hear it instead of just reading my lame descriptions. The shop manager said that it didn't seem to be rubbing "that much" in his opinion. He felt the brakes looked like they were wearing well but there could have been a slight variance in the rub which could indicate a slightly warped rotor, but nothing he would recommend putting it in the shop for at this point. He said the bearings didn't feel perfect, but they were nothing like they feel when he gets a bike with real worn bearings.

I know he can't tell any of this for sure and he was quick to make no promises, but I was quick to explain I was just looking for advice on whether I should let them dig into it. He knows my wife and I are planning to take a late April trip for 1800 miles including the Blue Ridge Parkway and he still thinks it is good to go for the trip. I think I am going to stop worrying about it. Maybe.

 

[Redfish Hunter]

Goodman I can see the rear not spinning freely due to the drivetrain but you should be able to feel the difference between the differential gears holding it back vs. a brake binding. You said the front wheel does not even make one revolution? There is no good reason for that. I would double check the front brakes. The front should spin fairly easily if everything is correct.

 

[ionbeam]

...You said the front wheel does not even make one revolution? There is no good reason for that. I would double check the front brakes. The front should spin fairly easily if everything is correct.

Actually, on the FJRs I've played with neither the front or rear wheels spin really freely. If I pull the calipers off and assiduously clean the pistons and everything else related to the caliper really good the front wheel will spin fairly freely but after a few days of riding, not so much again. Perhaps it is simply the piston seal design that causes this. The rear wheel has to turn the ring & pinion and right angle drive so it doesn't spin very freely either. Neither did the shaft driven rear wheel of my Honda V65.

 

[odot]

Your calipers are caddywompus, ion.....

 

[Geezer]

In order for brake drag to cause a significant drop in gas mileage, there would have to be a significant amount of drag. You would hear the brakes dragging against the rotor(s) and it would be obvious.

 

[odot]

....and your rotors will wear quickly.....and you'll go through brake pads three times faster.........

don't ask h ow I know.