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+--- Thread: drop in mpg (/showthread.php?tid=14694)
drop in mpg - pdedse - 02-25-2026
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?
RE: drop in mpg - rdprdp01 - 02-25-2026
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
RE: drop in mpg - Gone in 60 - 02-26-2026
Did you change gas source by any chance?
RE: drop in mpg - Cormanus - 02-26-2026
I've no idea why, but someone I know changed their fuel pump and found their mileage improved.
RE: drop in mpg - pdedse - 02-26-2026
(02-26-2026, 09:01 AM)Gone in 60 Wrote: 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?
RE: drop in mpg - Tev62 - 02-27-2026
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)?
RE: drop in mpg - pdedse - 02-27-2026
(02-27-2026, 08:17 AM)Tev62 Wrote: 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.
RE: drop in mpg - MagnaRider - 02-27-2026
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
RE: drop in mpg - dave - 02-27-2026
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?
RE: drop in mpg - rdprdp01 - 02-27-2026
(02-27-2026, 01:20 PM)dave Wrote: 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: