any ideas for bad fuel mileage

[pairodice]

1999 busa 10k micron race exhaust, pair valve mod, geared down 1 tooth in front, k&n filter dynojet power commander, RC wheels stock width, stock swingarm, new plugs idles and runs fine but mileage is low twenties riding 70 on interstate any ideas? bad tune maybe, elevation about 5000 feet

 

[Mr Bogus]

unplug the PC and run it... heck at altitude the thing is already probably a bit on the rich side..

 

[head east busa]

peg the throttle pretty sure that'll lower your fuel mileage

 

[Johnnycheese]

and go back to stock gearing

 

[Merlot]

Tyre pessure,and fuel injectors filthy

 

[Strife]

Wouldn't hurt to run some Seam Foam through it. Was just a thread on it.

https://www.hayabusa.org/forum/engine-performance-mods/110852-seafoam-safe-how-use.html

 

[OUTLAW1300]

Had the same problem. Running too rich. Check spark plugs, see if its wet. It may be your PC like mr Bogus said.

 

[djsin]

on the back of the air box on the left(as your sitting on it) side is a vacuum hose and sensor..make sure its connected and working, when my hose came off, the bike went rich and mileage skyrocketed down...lifted the tank and there it was little f-n 1/8 inch hose came off the sensor....

 

[GIXERHP]

Try stock gearing as Jonnycheese said!

Also what plugs did you use?

 

[dadofthree]

Go back to stock gearing

 

[suzuki4life]

stock gearing....dirty filter.....unplug the pc.

 

[BA BUSA]

Disconnect the PC...if the mileage goes up...get it remapped.

 

[Mr Bogus]

correct me if I am wrong but unless the thing has a speedo healer, the indicated gas mileage likely will not change (note INDICATED) with gearing change? (the speedo and actual mileage will be off however)

 

[GSXcite]

If I run anything over 87 octane gas my milage sucks.

 

[The Big Red One]

Going from 17/40 gearing (with slips) to 16/42 (with full system) def dropped my mileage, but with good mapping it wasn't THAT bad I went from low 40's to mid 30's. You can't blame that big of a decrease on just a -1 front sprocket. You're biggest problem is probably a wayy rich pc map

 

[NIGHTFLIGHT]

coast downhill,just coast everywere you can kick your feet.

 

[Wag]

In order of preference,

+1 on disconnecting the Power Commander.
+1 on checking the vacuum hoses. Also, if they are all connected, make sure they don't have any hairline cracks at the ends where they make connection.
+1 that the sprocket change wouldn't have affected it that much but still worth checking


When was the last time you synched your throttle bodies? Although that shouldn't affect it THAT much.

--Wag--