gearing change for better gas mileage? What ratio?

[angelsneverlose]

Hey guys,
Just like the title says, im looking at possibly changing my gears or one to get better gas mileage? Is this possible? Will i be really slow?

i commute about 60 miles on the highway a day and tend to average ~75MPH, this puts me at a relatively high RPM for the long a stretch and is eating up gas very quickly! Im having to put gas in my tank like every 2 days! So, is there a way to have the RPM on the highway lowered from like 8K average to maybe 6 or so? Anything lower will help right?

Let me know please! This is only my commuter/fiancés bike, so 'speed' isn't a huge necessity! I have an r6 for that

 

[Newmason]

75mph! Slow down then. 70 should be just fine!

 

[stuna]

I HAVE -2 ON THE REAR . i get 47-53 mpg . thinking about -3 . slow no i still can get in trouble

 

[JonKerr]

Slow- No. Your top speed will actually be a lot faster if you drop 3 teeth on the rear.
Sluggish- Yes. You will loose the very little bit of bottom end grunt this bike has. Probably not an issue for you though if your normal ride is all highway.

 

[angelsneverlose]

OK guys, so is there a brand or something i should look at? Can someone post a link? When you say 3 teeth, what are you talking about? As i mentioned, i know nothing about gearing . would this throw my speedo of a ton?

and which would be better, -3 or -2? How much of a change would i notice? Meaning if im at ~8K now at 75, will it be like 6K after -2? Do you noticeibly get more/better mileage out of your tank?

how much is install? is it hard to do?

 

[angelsneverlose]

75mph! Slow down then. 70 should be just fine!

this is flow of traffic around here on the highway... go twords mass and its more like 80mph, lol

 

[FitZ6R]

and which would be better, -3 or -2? How much of a change would i notice? Meaning if im at ~8K now at 75, will it be like 6K after -2? Do you noticeibly get more/better mileage out of your tank?

Stock rear sprocket is 46 teeth, so going -2 is a 4.3% change. Your revs will go from 8,000 to about 7,650. A -3 sprocket would get you down to a little under 7,500. Installation is an easy bolt-off, bolt-on. And since the stock speedo reads high, it will actually be closer to accurate (but the odometer will be off).

What kind of MPGs are you getting, and what are you hoping for?

 

[porky45]

Slow- No. Your top speed will actually be a lot faster if you drop 3 teeth on the rear.
Sluggish- Yes. You will loose the very little bit of bottom end grunt this bike has. Probably not an issue for you though if your normal ride is all highway.

While in theory the top speed would be faster...
I don't think the bike has the power to go any faster (top speed wise) then the stock ratio... I ran 136 fully tucked a few hundred rpms before redline and there was nothing left. (im' sure peak hp vs rpm's and what not probably comes into play...just saying though...)

You shouldn't be going that fast if you are "commuting" anyways

 

[Superzoom]

I agree with Porky that losing teeth on the rear probably won't raise top speed. Engine power is the limiting factor, and sometimes on a smaller engine, top speed can be higher in a lower gear.

 

[Superfly]

Stock rear sprocket is 46 teeth, so going -2 is a 4.3% change. Your revs will go from 8,000 to about 7,650. A -3 sprocket would get you down to a little under 7,500. Installation is an easy bolt-off, bolt-on. And since the stock speedo reads high, it will actually be closer to accurate (but the odometer will be off).

I think the odometer is reading high too. I saw a 15.8km from a friends honda VFR and I was showing 16.3km or something...for the exact same distance. The bikes odometer is prob in sync with the speedo...

 

[pyrocpu]

Not sure what others are getting as far as MPG goes, but I'm averaging 48.5MPG per my fuelly.com profile: FZ6R (Yamaha FZ6R) | Fuelly

As far as I'm concerned, anything over 40mpg is good enough--it's discretionary at that point. Any attempt for me to increase MPG is an academic exercise. If all else remains the same, being a 5% reduction in gearing = 5% increase in MPG, that's a 3MPG (rounded conservatively) gain. The parts & labor for a sprocket change really isn't worth 3MPG to me. YMMV, literally.

 

[Halon]

I get about 40-43 mpg with a very similar commute distance. I was averaging about 16-18 mph in my z32. So... 20 dollars every 2-3 days, or 8-9 dollars every 2-3 days...

 

[Superzoom]

I think the bottom line is:

- changing your gearing will have only a small effect on your mileage if you maintain the same speed

- your cruising speed will have more of an effect on mileage than a gear change

- a gear change is probably more important for changing where you are in the power curve at a certain speed, and for changing the speed at which engine vibration peaks

These are all layman predictions/assumptions/guesses, but are based on anecdotal evidence, which is as good as fact .

 

[Bigevildoer]

Hey guys,
Just like the title says, im looking at possibly changing my gears or one to get better gas mileage? Is this possible? Will i be really slow?

Well, our bikes read around 8.5% high on the speedometer - so our mileage is ticking up at a 108.5% rate as well. According to Czbdel, he swapped the front sprocket out with a +1 tooth and now his speedometer is exactly correct.

So, in theory, you should gain an equivilent 8.5% in fuel mileage. Sure, this is quick and I didn't sit down and so all the math, but it's in the ball park.

Later!