97 CB750 Nighthawk-Poorish Gas mileage
I just picked up a 97 nighthawk cb750 last week, with 40k on it(well, says 40k, but the speedo/odo wasnt working when I got it, so who knows...). Anyway, the bike seems to run great, but for some reason I am not getting the MPG that I think I should be getting.
Right now, on the freeway I am getting about 37-40mpg.(at about 70mph)
Not horrible, but I've seen plenty of people claiming to get 40-50mpg. Since I got the bike, I've fixed the speedo(the wire was broken up by the front wheel hub), changed the oil and replaced the spark plugs.
I travel 200 miles per day, about 190 of it on the freeway. My speed ranges from 65-75mph, occasionally 80. I weight 150lbs. Air pressure in both tires is 33 cold.
As a test, I filled up the tank, and got back on the freeway, and kept my speed between 58-65mph, and went 70 miles, and filled up as soon as I got off the freeway. I was able to squeak out 40mpg...But once again, I've seen people say they beat on the bike and still get 40+, and I was riding gingerly getting 40 at best.
The bike does not leak gas when sitting(holds a full tank overnight) and otherwise seems to run well. When on the freeway, I keep a constant speed.
I will be replacing the air filter very soon.(could this effect the mileage that much? Its dirty, but it didnt seem too excessively dirty...)
Any ideas about why my mileage is(seemingly) bad?
Otherwise, I'm kinda stumped on where the gas is going...and not that my MPG is THAT bad, but its a 200 mile round trip to work, and I'm trying to make it home-work-home again without filling up.
I'll be ordering a 16t front sprocket to help keep the revs down a little bit, since its a 95% highway bike.
I also have a Vance & Hines exhaust, if that makes any difference.
Am I just expecting too much? I know 37-40 isnt horrible, but I feel like it could/should be better.