drop in mpg

[pdedse]

I've never gotten over 50mpg, the norm for me is around 45.  

Of late, with no significant changes other than weather, it seems I'm getting 38-39.  I don't check that often, I just do a quick mental calculation while filling and if it's above 43 I don't think much about it.  What are some reasons for a noticeable difference?  I keep the tires inflated at 36/42.  The valves were checked once at 14k miles, in spec, at which time the spark plugs were replaced.  Currently it has 31k.  Starting is normal.  I don't detect any drag on brakes.  Thoughts?

[rdprdp01]

Pdedse, my remarks are based more on my experiences with Porsche cars than motorcycles, but there may be some crossover. In instances where I saw a significant drop in mileage, causes were traced back to

Dirty oil
Clutch performance
Spark plugs
Vacuum leaks
Brake pads
Tire pressure
Tire wear

Sound like you have already discounted a few items on my list. I am sure our friends on the Forum can be of more assistance than me. David

[Gone in 60]

Did you change gas source by any chance?

[Cormanus]

I've no idea why, but someone I know changed their fuel pump and found their mileage improved.

[pdedse]

Did you change gas source by any chance?

I don't fill up at the same station each time, so yes.  I think it's been high 30s for several tanks of gas.  I'll keep my eye on it and be a more precise to see if it's fluctuating or stays.  

Can lower mpg be a sign of tightening valves?

[Tev62]

Have you put it up on the centre stand and ruled out any mechanical issues with the wheel bearings, brake pads/calipers, drive chain (links getting stiff)?

[pdedse]

Have you put it up on the centre stand and ruled out any mechanical issues with the wheel bearings, brake pads/calipers, drive chain (links getting stiff)?

I did change out my brake pads around Christmas time, so that's a good reminder to check for drag; drive chain is at 31k miles.  Wheel bearings...not sure about a check for that.

Thanks.

[MagnaRider]

I think the only check for wheel bearings is side to side or up and down play. Or if the hub is excessively warm after a ride

[dave]

I never thought that using a different brand of gasoline would make a difference in fuel mileage, but after reading a comment above it got me thinking. I have kept a record of my fuel mileage since day 1 with this bike, and I now have over 40,000 miles. I noticed my fuel mileage had increased by about 7%, but thought that maybe this was because the engine had fully broken in. I used to buy fuel at whatever name-brand station was convenient, but I have been using Chevron fuel exclusively for the past three years, and now I see that my increased fuel mileage may have something to do with the fuel brand, or maybe this is just a coincidence? Your thoughts?

[rdprdp01]

I never thought that using a different brand of gasoline would make a difference in fuel mileage

I only use Chevron gas and have averaged 50 MPG. It does make a difference because of the detergent additives and other aspects of the refining process. The storage tanks and maintenance practices of the station matter, too.

Here is a video that i believe is fairly accurate: