Not Your Typical Mpg Loss

Hi everyone,

I got a 2006 VFR800 ABS two months ago 15,000 miles on it. I got it from a guy that's been assuring me that the bike has no problems whatsoever, I believed him since the bike looked really clean. He said he recently replaced spark plugs, coolant, oil (around 2000 miles ago).

After having the bike for couple of days and putting around 300 miles on it something seemed odd. The power was down and I was getting around 26 mpg. After some troubleshooting I found out one of the spark plugs was unplugged! (he probably forgot to reconnect it)

I reconnected it and the power and mpg's went up to 30-32 mpg of 50/50 city/hwy driving. The bike is completely stock.

So far, I don't think it's the thermostat the bike warms up fine and runs at around 174F on the highway and gets hot in traffic ~200F. I checked the spark plugs they look fine. K&N filter looks clean. There's no smell of gasoline when the bike is running. The fuel pressure regulator is not leaking.

Could you guys please help me of what I should take a look at to try and fix that issue because fuelly indicated that the average mpg's for that bike is around 40.

Thanks!

 

You've checked all the usual suspects.

Is the power good since you plugged the plug wire back in? Pull strong to redline?

 

What does the bike idle like once warm? The wax unit in the throttle body is a pretty common failure point. It could be stuck leaving the enrichment circuit meant for cold starts open. Meaning your bike is running rich?

Second the pull to redline as well. Listen for that exhaust note change. Make sure v-taaaak is working.

 

could it possible be WOT all the time

 

Stoopid question: Are you taking the previous owners word for it, "completely stock"? Gearing change, PC, O2 eliminators?

 

Power seems to be okay, but I can full throttle it without front wheel taking off usually (not sure if it's laking power or not). Vtec kicks in just fine. It starts and idles just fine as well. Gearing seems to be fine because on the highwat RPMs are usually around 4-5 thousand at ~60mph.
I have PCV I rode bike with it and without it, the change in mpg is about 1-3 mpg.

 

174 degrees sound low. is it cold where you live?

But I am not super familiar about the vfr800 yet.

 

I live in Portland, OR. It gets to that temperature after about 3-5 minutes of riding so I though it's be fine.

 

anywhere around 175 and up is normal temp for these bikes, they LOVE cool air. My 6th gen will run steady at 175 until the ambient temp get to 80 degrees or so then climb steadily and quickly from there.

15,000 miles in 9 years isn't a ton, and if not properly stored in between rides, something could have gotten gummed up. Try running some injector cleaner and/or some sea foam through it.

Check the air filter, make sure the tires are inflated properly. Are you a bigger fella? I noticed a sharp drop in mileage when I gained a bunch of weight, and the mileage is slowly coming back as I am slowly losing the weight.

 

I just dumped some fuel system cleaner in the tank we'll see if it'll help.

Air filter has been replaced recently. I'm average weight 170ish.