curious thing happened after my chain swap

[Guest]

I had a 16T front and 40T rear 630 chain and after the usual outstanding help I got here I went to a 18t front and 48t rear 530. The old chain was beat to death, was not an o ring chain and like most chains that are crapped out it would have tight spots when trying to adjust and then a big sloppy spot.

My new setup gives me a lower top speed but makes it a fair amount more perky. It of course raised the rpm at any given speed.

So I just went through my first tank of gas with my new chain set up and ..... I gained 3+ miles per gallon!?

I fully expected to lose some mileage since I am up on rpms throughout the ride but I went from a steady 40 miles per gallon over the last 4 or 5 tanks to 43.3 after the chain swap.. Im thrilled but ... what do you think happened.

[dorkburger]

Volumetric efficiency. Increased intake charge speed. Likely something along those lines. Lower engine speed doesn’t necessarily equal better mileage.

[Steve]

Maybe now you will understand and agree when we say (over and over again) "Let it SPIN".

.

[Sandy]

All motors have what I call their happy place, as in rpm. I think you found it.

[Brendan W]

The old chain may have been absorbing more power.
Flapping around and noise is not free.

[Boriqua]

Did 80 miles yesterday at 75-80 mph and it really did feel in the zone.engine was just singing right. Very happy with the new gearing!

[Boriqua]

So I filled up today after my long highway jaunt from the post above and a few extra miles. Now considering it was singing along the highway at about 5000 rpm I was curious to check mileage.

45.25 MPG.

Now I never checked the mileage the last time I owned a GS 750 in the 70's but that is better than my last three bikes. I am assuming that is good MPG for this machine.

It certainly does seem to like to spin some!!

[wymple]

I get slightly over 40mpg on my shaft driven 850, and I have it a touch on the rich for jetting. I like mine that way. So 45 seems reasonable to me.

[hillsy]

With the changed gearing your motor probably isn't labouring as much. An engine under load will consume more fuel than one that is coasting.

[hjfisk]

Most inline four cylinder bikes get there best fuel economy between 5-6 k rpm, they seem to burn the fuel more efficiently. The newer fuel injected models may differ some.A couple years ago I did a trip out to Colorado with a friend of mine, he was riding a HD ultra classic and got 51-52 mpg @ 65mph. I was riding my 05 FJR 1300 @65 mph I was only getting 39-41 mpg, but if We ran at speed up 75-80 I got 47-49 mpg and he got 35-40 mpg(. And started using oil) so the happy medium was to run at 65-70 and I just follow him in 4th gear and kept rpms up

[dweller]

Did you adjust for the fact that your odometer is now off?

[dorkburger]

Odometer runs off the front wheel. It wouldn’t change.

[gustovh]

All motors have what I call their happy place, as in rpm. I think you found it.

Yes Sandy and yours is something north of .....well fast.

V

[Boriqua]

Changed over to my summer oil about 300 miles back and thought it would really hurt my mileage since its 20w50 but I checked today and got 48mpg from the old girl on my last tank !! WOO HOOOOOOOO

It really does seem to enjoy a little more rev.

[bwringer]

Spin to win!

Grip it and rip it!


Seriously, these engines LOVE to spin. They NEED to spin. If you don't wind your GS750 or GS850 to redline a couple of times per ride, you're missing out and making your engine sad. They hate putt-putting around like little old ladies or V-Twin pirates.

Once you get comfortable with RPM, the GS750/850 engine is one of the more entertaining powerplants ever created; that rush between 6,000 and 9,000 is downright addictive.


And personally, I think if you're worrying much about mileage on a motorcycle, you're doing it wrong. I pay some attention to mileage so I have a rough idea of when to fill up (you can't trust a GS gas gauge), but riding to maximize mileage is boring.


And yeah, I've never quite figured out how Harleys get such surprisingly good gas mileage. I guess the EFI is set up REALLY lean to pass emissions, and mileage efficiency is one side effect.