Opinions on bad fuel economy

[Z3R0_zhift]

I'm riding a FZ6 S2 2008. It's been two weeks that I went for a valve clearance (change timing chain, tensioner, gasket, coolant), clutch plates on my ride and a new battery. Oh, I changed to new metzeler z6 Roadtech front and rear. There's slight improvements on the fuel consumption which normally I get about 240km before reserve but now 245km. Estimated distance for overall mileage I am getting is 320km. Currently using BMC filter and scorpion slip-ons, no engine mods, decat or anything. Ain't sure what the previous owner did with the bike though.

Sprocket mods just rear +1. It's been 3+ years and is was still getting the 240. I do overfill the fuel tank but there weren't any issues so far. I just adjusted the throttle cable for a better throttle feel but other than that it was fine. There's a ticking sound that I had notice on my left side for a long but there weren't any issues. Stationary idle was sometimes at 1250-1000rpm.Some thoughts on my mind were:

1) Changing gears from 6k-7k rpm
2) Sprocket sizes as highlighted by a local mech
3) Magnetic coil/ stator and regulator
4) Overwork pistons or piston rings
5) Engine cylinder block worn
6) Air filter change, the outer rubber is wearing off

There's no issues on the handling but I realised the bike is getting faster in warming up after I have done the servicing. Regular changing of engine oil is 5-6k km and original ngk cr9ek every 6 months. Rarely wash the bike though,ain't sure whether that has to do with anything but I do a maintenance of cleaning my chain and lube every 2 weeks. Previously there were kinks to the chain (1 yr plus old) but after the tire change its back to normal.

Looking at touring and commuting mods, and kinda fixated on the bad fuel economy as compared with a friend and others online. Thoughts anyone?

 

[beatle]

What's your actual mileage computed from fillup? Not sure what mileage I hit the reserve, but 45mpg is normal for me with just Scorpion pipes, stock gearing, and probably a dirty air filter. How many miles are on the bike? I'm guessing around 24k miles since you just had the valves checked. Were they all in spec? If they were off, how much? These engines are pretty reliable so I doubt it's engine wear unless it was overheated at some point. Do you smell fuel or oil burning off after a ride? What oil are you running?

 

[FinalImpact]

Some conversions brings us to this: hint I hit reserve after consuming ~4gallons.

15.141 liters = 4 gal
245 km = 152.23 miles

245km/15.14l = 16.18km/l = 152.23m/4g = 38.05 mpg

My US 08 FZ before mods was getting 45 - 55 mpg, so ya, yours seems off assuming our reserve light comes on about the same time.

Over 1.0 mile the change from 16/46 to 16/47 rolls out to 0.025miles less. Pretty negligible.
152mi*0.025 = 3.8miles short compared to 16/46 gearing....

In 6th gear...
6000 RPM = 72.26mph and 1.204 miles 46/16
6000 RPM = 70.72mph and 1.179 miles 47/16
6000 RPM = 69.25mph and 1.154 miles 48/16

Things that could help:
A clean free flowing air filter.
Better chain lube.... All power is through that chain...
A different fuel blend or supplier. Maybe even try higher/lower octane.
Engine oil, tire pressure, brake drag, spark plug type and gap, all come to mind.
Verify CATs are NOT plugging.... Restricted flow can hurt MPG.s
Reset ECU with Battery disconnect and verify fuel economy.

The S2's try to maintain 14.7:1 Air Fuel Ratio and I'm running 13.0:1 AFR and still get 45mpg.

As mentioned earlier please calculate the actual km/L and give us a real number. That would help as these are just guesses.

 

[agf]

For my fuel usage Look at by signature on a pc , I'm on my phone at the mo. Anyway I commute 5 days a week, 10 km each way
Hit reserve at about 215-230 kms and usually need about 15 Ltrs to re fill
I think it's about 6.8 / 100km
And drops to 4.5. /100km when I do a long weekend hey ride


my iPhone post using Tapatalk - sorry for any shpillong mishtooks i has fat fingies

 

[Zealot]

Kind of related to fuel economy, I've got a 2015 Cruze 1.4L Turbo Eco in manual. The manual says that the 1500-2500RPM range is for regular operation, and you shift from 2500 up. Now, this car has a lot of low down torque for what it is, and you can run it at 1500rpm no problem and it doesn't so much complain. I'm talking like, 6th gear at 40~ or so MPH and it's totally cool with that. Thing is, I've been doing an experiment lately and found that revving it a bit higher in a lower gear has given me better mileage. I figure it's got something to do with the fact that to maintain a given speed in 4th gear requires a lot less throttle than 5th or 6th, not to mention it's running the turbo slightly faster which could further improve economy. It seems like keeping it within the powerband and the likes, around 2000 RPM, has been netting me better success with gas mileage than trying to 'save' by running it lower in 5/6.

I wish I could ride my bike right now to experiment some more, but I don't have the ability right now. I'd also consider changing your stance slightly, as sitting up like a sail in the wind could affect mileage too. Not saying go full tuck or anything, but if you could sit a little more aggressive you might get better results. Just speculation, mind you!

 

[FinalImpact]

^^ true of the bike too. It likes to rev. Naturally aspirated engines like this bike engine add fuel when the vacuum drops. Meaning - most cases they will get better economy pulling more rpm in a lower gears like 2nd/3rd at 45mph than 6th at 45mph.

Its about imposed load seen by the engine and how it drops the intake manifold vacuum. There videos on fuel economy driving while watching intake manifold pressure. Worth a watch then you see the relationship of gearing up not helping torqueless engines get better mpg.

YouTube

 

[TownsendsFJR1300]

Checking for excessive brake drag would be the first thing I'd be checking.

Yamaha recommends NEW brake caliper SEALS every TWO YEARS. In real life, IME, 4-5 years is more realistic.

My front brake drag (original seals) went from approx 3/4 rotation, "free hand", spinningas hard as I can, by hand. With the new seals, about 4.5 rotations after the rebuild.

About three years later, still at 4 rotations. I blow excess brake dust out regularly and when replacing my front tire about a month ago, cleaned excess goo off the pistons while the calipers were off...

I average about 48-53 MPG around town, shifting around 5-6k,

 

[Zealot]

^^ true of the bike too. It likes to rev. Naturally aspirated engines like this bike engine add fuel when the vacuum drops. Meaning - most cases they will get better economy pulling more rpm in a lower gears like 2nd/3rd at 45mph than 6th at 45mph.

Its about imposed load seen by the engine and how it drops the intake manifold vacuum. There videos on fuel economy driving while watching intake manifold pressure. Worth a watch then you see the relationship of gearing up not helping torqueless engines get better mpg.

YouTube

Ah, that would explain why I've been noticing better results then!

A guy I work with suggested I try running with a vacuum gauge hooked up to see how it affects my mileage. Really interesting video, thanks for sharing!

 

[Z3R0_zhift]

Thanks y'all for sharing. I just find it quite mysterious on what are the setbacks for the bad fuel economy.

What's your actual mileage computed from fillup? Not sure what mileage I hit the reserve, but 45mpg is normal for me with just Scorpion pipes, stock gearing, and probably a dirty air filter. How many miles are on the bike? I'm guessing around 24k miles since you just had the valves checked. Were they all in spec? If they were off, how much? These engines are pretty reliable so I doubt it's engine wear unless it was overheated at some point. Do you smell fuel or oil burning off after a ride? What oil are you running?

The bike mileage was 10400km. Thus, due to the long mileage I decided to do the valve clearance and etc required. No burnt fuel or etc after a ride. I left the bike to the mech for the maintenance and did ask whether they were off. It wasn't too much he said.

For my fuel usage Look at by signature on a pc , I'm on my phone at the mo. Anyway I commute 5 days a week, 10 km each way
Hit reserve at about 215-230 kms and usually need about 15 Ltrs to re fill
I think it's about 6.8 / 100km
And drops to 4.5. /100km when I do a long weekend hey ride


my iPhone post using Tapatalk - sorry for any shpillong mishtooks i has fat fingies

I commute about 40-50km daily and do some long weekend ride too. Before this, it was 235-240km before hitting reserve. I manage to ride on for another 65-70km before I decided not to take a risk.

 

[Z3R0_zhift]

^^ true of the bike too. It likes to rev. Naturally aspirated engines like this bike engine add fuel when the vacuum drops. Meaning - most cases they will get better economy pulling more rpm in a lower gears like 2nd/3rd at 45mph than 6th at 45mph.

Its about imposed load seen by the engine and how it drops the intake manifold vacuum. There videos on fuel economy driving while watching intake manifold pressure. Worth a watch then you see the relationship of gearing up not helping torqueless engines get better mpg.

YouTube

Normally I change up to 3rd-5th gear on the highways and 1st-3rd gear on the street. However, I try to maintain throttle on my highest gear in both conditions 5-6k the most. Is there an issue?

Checking for excessive brake drag would be the first thing I'd be checking.

Yamaha recommends NEW brake caliper SEALS every TWO YEARS. In real life, IME, 4-5 years is more realistic.

My front brake drag (original seals) went from approx 3/4 rotation, "free hand", spinningas hard as I can, by hand. With the new seals, about 4.5 rotations after the rebuild.

About three years later, still at 4 rotations. I blow excess brake dust out regularly and when replacing my front tire about a month ago, cleaned excess goo off the pistons while the calipers were off...

I average about 48-53 MPG around town, shifting around 5-6k,

I was wondering whether the ABS system or wheel bearing had to do with the consumption as well. Perhaps I'll check to see the wheel rotation. For front and rear, it should spin 4 rotations or just your estimate? Well I guess if it's due to change den perhaps I might as well.

Regards to the fuel consumption, 245km per 15.8 L is about 15.5km per litre and 6.44litre per 100km. 60ml per 1 km.

In mpg, it's 9.635 miles per litre, 70.49km per gallon, 0.1 litre per mile & 0.0142 gallon per km.

 

[TownsendsFJR1300]

I was wondering whether the ABS system or wheel bearing had to do with the consumption as well. Perhaps I'll check to see the wheel rotation. For front and rear, it should spin 4 rotations or just your estimate? .

The front wheel is the worst offender. Its very rare the rear drags. Especially the S2. The more the pistons, the more it'll drag over time. If you can get 3/4-1/2 a "free spin" your ok,

Simply going for a ride say, 10 minutes, 50 MPH, then stop with the REAR BRAKE ONLY. Feel the front rotors. If their warm to hot their dragging too much. Same for the rear (but vice versa)


For an S1 (front brakes) and for ALL REAR brake calipers, their "floating calipers". You'll see two black, rubber boots surrounding the mounting bolts / sliding pins. If their gummed up, the caliper will NOT center itself, cause excessive, uneven wear, etc. Maintenance is pretty simple. Remove and clean each mounting hole/boot/pin. The apply BRAKE SPECIFIC GREASE until it slides back and forth nice and smooth. NOW, it'll center itself. I'll do my rear maybe every two years or so...


Re the ABS, it shouldn't make a difference unless you have air in the system...

 

[Z3R0_zhift]

I tried the front spin it's about 1/4-1/2. I do see one of the pistons at the front were rusted and so I might do a quick clean on them.

Sent from my GT-N7105 using Tapatalk

 

[yamihoe]

I agree, I had an issue with my R6 calipers a while back, and I pulled each piston out and polished it thoroughly. It worked well for me that time, I had another issue and my air filter was dirty, to me I really didnt see it as that bad but I soaked it in zepp and oiled it and my mpg's shot up. With mine, being as I have quite a few miles on mine I have come to suspect the bearings might be showing their age, not going bad but just not being as free as they once were when they had 1/2 the miles on them.

 

[TownsendsFJR1300]

I tried the front spin it's about 1/4-1/2. I do see one of the pistons at the front were rusted and so I might do a quick clean on them.

Sent from my GT-N7105 using Tapatalk

What happens is the rubber seals for each piston, over time, get hard, un-pliable and DON'T retract the pistons. Thus they stick/drag.

The exterior rust on the outside isn't what's the issue(but should be cleaned up).

For the S2, (4 pistons per caliber), I spent back then around $80 for all the seals delivered (from Partzilla). I'm sure its more now and the S1 a bit cheaper with half the seals... It took me longer to bleed the system than to R&R the seals, clean pistons, etc.. Major difference once done...

 

[FinalImpact]

Brake drag; perhaps this is too much detail but something to noodle on.
Two things directly relate to pad retraction. The variance of the disc spinning through the pads pushing them away a small amount and the return spring in the master cylinder - but ONLY when there is NO air in the system.
When air is trapped in caliper or lines, all bets are off and its up to the disc to move the pads and caliper pistons.
If however, the system is purged of air, the spring in the MC helps retract the caliper pistons drawing the pads away from the disc(s). It does this because the fluid doesn't easily separate.

JM2C but dirt and grime on the seals and air in the lines are the two greatest factors in brake drag on a non floating caliper. These do not have bellows style collapsing dust boots so the seals typically create equal drag both directions (in/out). Thus they do nothing to retract the pistons.

Pressure bleeding your brakes system yearly is the best thing you can do to keep it healthy short of cleaning grime from the pistons. Obviously rust and debris stuck on the pistons can and will damage the seals so, clean is good for longevity!

 

[Z3R0_zhift]

Thanks for the advice and wisdom. I have done pressure bleeding for the front brakes before but no air trap inside. I'll properly try to clean the rust in the pistons/ calipers without breaking them apart with the seals.

Sent from my GT-N7105 using Tapatalk

 

[TownsendsFJR1300]

Re the seals update.

If not noticed/noted earlier, when when my brake drag was down to under 1/2 turn I rebuilt them (new seals).

WITHOUT DOING ANYTHING ELSE, I PICKED UP 4 FULL ROTATIONS..



***I'd also like to note, that maybe 6 months BEFORE new seals, I pulled the calibers apart, cleaned spotless etc.

I did use brake specific grease on the seals(designed for that) upon re-assembly.

THAT helped a bit for about six months (got about a full turn before the dragging was back**.

They were very clean then BTW, no corrosion either




The rubber simply hardens up, and makes the pistons STICK.

Anyone that's pulled one apart (for seal replacement) has found at least one piston a real bit.h to remove.

That's likely why YAMAHA recommends replacement every TWO YEARS.

 

[FinalImpact]

Thanks for the advice and wisdom. I have done pressure bleeding for the front brakes before but no air trap inside. I'll properly try to clean the rust in the pistons/ calipers without breaking them apart with the seals.

Sent from my GT-N7105 using Tapatalk

In the tech section is a sticky on brake bleeding.

I use a syringe, suck out all the old fluid, clean the reservoir, fill it and pressure bleed with a hose and wrench.
Once it feels good, I hold system pressure and tap each caliper from the bottom in an upwards motion to jar any remaining pockets of air free. This process has served me well in getting a firm lever and air free system.
Do not tap in the direction of piston travel, just upwards from the bottom. The action allows the small bubbles to rise, condense and escape when the bleeder is opened under pressure.

Give it try...

Also a shoe string works great for cleaning the pistons. Its in that same thread. Post 7. Unfortunately the pictures are gone after server migration to new software.

Brake Bleeding

 

[Z3R0_zhift]

Thanks guys. I'll keep note and clean the necessary stuffs before replacing the seals. Never did one before on seal or piston replacement on my own. Prolly will take me a few hours doing both front. Thanks much!

Sent from my GT-N7105 using Tapatalk