I need to pick some brains on here. I've owned my 2002 Hornet 919 for almost a year. Always got right around 40 mpg on it until a couple months ago.
Long story short, I got some diagnostic work done after my MPG's went down about 20 percent out of no where and I had some low end (up to about 1,500 RPM) bogginess. It was concluded that my injectors were dirty and that my fuel pressure regulator was compromised.
The injectors were cleaned, I replaced my old air filter with a new K&N and replaced my fuel pressure regulator too. The bogginess is gone and the girl moves smooth and fast once again. But my MPG's are still down around 34 from about 40.
Anyone have pointers or other things to look into that would be causing the dip in MPG's? I read somewhere on this forum recently about a PC III board or something like that that could make the air-fuel ratio less rich. Is that something I should look into?
Any help would be greatly appreciated.
Looking forward to interacting with some like-minded peeps on here.
I'm saying 'put the stock filter back on' so he's back to baseline - he had many things done to the bike, so we need to eliminate as many variables as possible. Also old clogged stock filter is not equal to new stock filter.
Just went out to do a quick look-see and listen to something I noticed after replacing the FPR. A squealing-like sound when I turn the key. I'm not an expert but it sounds like it's coming from inside the tank and therefore the fuel pump (I hope not but that's my fear).
I don't know how good an idea it is, but maybe you could run some fuel system cleaner through it. I like the Seafoam brand my self. I've used it on my cars, trucks, lawn equipment, and motorcycles. And +1 on removing the K&N. The oils from the filter can sometime get sucked into the intake and cause odd issues. Kept fowling out my mass air sensor on my truck.
Just read through the entire thread (after five months lol) you posted and the sound is the exact same as what I'm suffering from. Sounds like I need to replace my FPR (again) and make sure it is completely ready to install before I do so.
I've been riding less recently due to work, but I have more time to do so now so I'll be working on getting my MPG's back up to where they were before.
Once I replace the FPR and have the miles to check the MPGs I'll report back.
I think I need to pull off my FPR and see if that 'seal' is blocking fuel return like it was in the thread that is linked to above. That seems to be what caused the fuel pump squeal in the other thread. I'm hoping to get this done tomorrow.
Great news on this front! I found some time yesterday (Thanks, MLKjr!) to pull off my FPR and lo and behold, that rubber cap was sitting there cramping my fuel's style. I took it off, put everything back together and two takeaways: 1: the 'squeal' of the fuel pump is gone and 2: after a ride to the office and back today, my fuel mileage is back to where it was before my original FPR kicked the bucket. I rode 163 miles before the fuel indicator light came on!! So pumped, and so happy you were all able to lend a hand on this, especially you Doc Lizard!
Much thanks again and I'll be around here more often to chime in when I can.