Seriously Bad Fuel Economy

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Well-known member
Aug 2, 2010
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Harrisburg, PA

As I installed the wiring harness all of the connectors were perfect. No currosion, wires and insullation were like new. There were absolutely no signs of an impending spider bite.

Lets say for sake of argument that my bike was on its way to cooking the ground. By adding the harness will that now stop that from happening or have I just delay the inevitable?
The intent of the harness "fix" is to prevent a failure from ever happening. You are supposed to do it before you have an S4 meltdown. By providing a better, low resistance path to ground you will keep the spider from heating up.

It is remotely possible (although unlikely) that, even though your ground spiders looked pristine, the impedance of the path to ground was causing issues in the fuel injection system that you could not detect with the naked eye. The only way for you to conclusively determine if the harness is what actually changed the MPG (and it wasn't a coincidence) is to remove the harness again and see what happens to your mileage.

The coincidence might be that you got a different (better) fuel mixture on the last fillup? Do you usually fill at the same station? Same pump? (the pump could be metering FUBAR)

BTW - using higher octane fuel than what your engine needs is just pouring your money down the drain. The premium fuel doesn't have anything additional to help keep your engine clean, just octane additive to prevent pre-ignition(detonation). It does not contain any more or less energy than regular unleaded. If you don't have a higher compression engine that is prone to pre-ignition then the higher octane does nothing for you. Luckily, it will not cause any problems either.
Eggzactly, could not have said it better. And although I did this to a 0 mile '10 bike, there are no guarantees I wont get bite. However I like my chances over stock wiring. Also all spider points should be scheduled maintenance by the owner, additional ground harness or not.



Some call me... The STIG!
May 23, 2007
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Orange County, CA
Maybe some one needs to learn how to fill the tank with petrol.

Hmmm. I'd guess the common threafd so far is both you guys messed with the spark plugs ands it was mo betta. Maybe your wires are having an issue and reseating them helped.

Just sayin', all seems rather strange, but glad it's back to normal. ;)