Kawasaki Motorcycle Forums banner

Performace gain v. MPG drop

1407 Views 15 Replies 13 Participants Last post by  Aifwikir
After reading through a lot of the threads on the forum about intake mods (like Constrictor's mod), exhaust replacement and the Fi box, something that I really haven't seen mentioned is how much did your MPG drop?

Even with a cager, you expect to have a MPG drop with some performance mods. So, though I am looking at this info for the VN900 line, any info would be nice to read.

What was your (estimated) MPG drop after pipes, intake and Fi box?
If you added the Scootworks front pulley, how did that effect your MPG?
1 - 16 of 16 Posts
That's why my intake is stock on my Nomad. It get between 40 and 44 with my Roadhose 2 to 1 riding double. And that's low enough for a bike to me. They have car's with over twice the weight drag and horse power that get that much.
I did the caddman air mod, cobra fi2000r and HK strippers and lost about 4-6MPG on my meanie.
Not to sound like a mpg disclaimer on a commercial, but..."your mileage will vary depending on your driving habits and driving conditions". True. For me personally, when I added a Thunder intake, PCIII and pipes to my former bike, a Suzuki C50T(805cc cruiser), at first I observed a 3-4mpg drop. Then, I had it custom mapped, which dialed in the air:fuel ratio's and I was back up at 40-42 mpg, which is where I was at bone stock.

The "driving habits" is the killer though. With the mod's on board, I cannot resist getting on it every now and again. When I drove the bike's arse off, I got 35-38mpg; when I drove regular, conservatively... 42mpg combined average (street/highway).

Hope this helps you get a bearing on mod's and their affect on mpg.

No worries Daryl. :)
I know what you mean about how you drive make a difference.
I will be going from about 50 MPG on my Shadow to what about 45 ish when I get my VN900, so I am already down on the MPG side. :(
I thought it interesting that all these posts about the great mods that are done, but no one really commented on the "down side" of it all.
+1 DS06
Your MPG is inversely proportional to the strength of your right wrist.

My 1600 varies from 30 to 38... no change from stock.
My best tank was 45, rolling through AZ 2-up with my club, on the low-speed roads from Williams to the Grand Canyon, along the south rim, and on over to the eastern highway. Couple of the Harleys managed 52mpg on that trip.
I dropped about 2mpg in town. Not sure on the hwy mpg yet.

I used to average about 37-38mpg in town, now I average 35-36mpg in town.

So I may lose about 10 miles per tank after the Pipe, intake and PCIII. But that is negligible and it only cost about an extra $1 per tank. For the sound, fun and HP increase, it's not an issue for me.
I get the same with the mods as I did stock. But mine is a carbed bike so it's easier to "dial it in". No electronics/computers necessary. Set it up to run a little rich and clean/change the plugs at 4k miles.
I have only done the Pulley Mod. And its a little tricky to get milage. Mainly because I was figuring miliage with the odo that read high. Which gave me better fuel milage readings. Now with the pulley installed the milage reads low. So now I get worse fuel milage readings. So I use the GPS to figure milage now and I usually get low 40s. I can get more if I baby it.
I noticed on my Nomad it dosn't take much agressive throttle to drop from 42 to 36.
If I were thinking gas mileage I guess i'd stay away from a v twin. But when I make my bike louder or a wee bit peppier I'd expect mileage to go down if only cause the techs at Kawi have tried for the best balace DOT allowed. And of course just cause a fun bike is more "twistable" :cool:

I belive no one comments on the "down side" of mods cause the gas issue isn't even considered.
My 900 stock was around 48-50 mpg.
Didn't notice a drop w/ debaffled stock exhaust.
Front pulley wasn't on long enough before doing exhaust, intake and Fi2000r to check mileage.

Consistently getting around 43-45 mpg.
Doubt pipes made any difference, pulley should have helped a bit.
The Fi2000r adds fuel right out of the box, so it's a matter of getting the settings where your mpg is best and it runs well.
Pipes didn't make any difference in the way I rode it, but after the intake, I do occasionally pull away from a stop with a little more "twist" in my wrist.
The mods were mainly for appearance. The gains in appearance/performance were worth the 5 mpg hit. I'll tweak the pots again in the spring, and see if I can gain a little more.
Keep in mind that the pulley will affect your speedometer/odometer error, just as the Speedo Healer will. Speed is read from the transmission output shaft.

You dropped 48-50 down to 43-45, so that's about a 10% drop. Your speedometer was also brought about 5% closer to being accurate, so at least half of your economy loss is actually due to the speedo correction and not a true economy loss.

BUT... A lot of people change sprockets on the Honda VLX600 to give it better "highway legs", and though it does drop cruise RPM, nearly everyone reports a HUGE economy loss. One guy in my club can barely make 80 miles before going to reserve.
Same thing often happens when going to oversized tires in an attempt to lower highway RPM.
I got 45 mpg on my mean streak prior to mods, like clockwork, no matter how I rode - cruising or hard and fast. After adding a big air kit and PCIII, it went down to 42. But my HP is now 15hp gain over stock... I'll sacrifice 3 mpg for that.
I lost about 10 miles per tank after pipes, intake, PCIII. The install of the PCIII map and intake was when I lost a few miles per tank but also got my biggest performance gain.
On my 900 I was getting 54mpg before I installed the overdrive pulley. Then I got 48 mpg and my speedometer is on the money.

1 - 16 of 16 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.