MPG change does this make sense

So, I have begun my saga for my Sturgis trip and I stumble across something strange...maybe someone can help me clear it up??!! Back in the day, I install PCIII and did stage 1 upgrade. I went from approx 45mpg to 35mpg....didn't like it, but accepted it (used the download map). about 2 weeks ago, I had my bike in for 20K service.....(I had the bike in for the 1, 5, and 10K (changed my own oil for the 15.....). Decided that with the sturgis trip, I wanted to make sure the bike was top notch. after that service, I took the bike to Chuck's place....did a complete gas tank switch...disconnected the gas lines, drained the gas, pulled out the fuel pump...put on the new tank, attatched everything and bam....done. NO other changes to the bike or the PCIII....... Now, on this ride, something strange happens....I get to 150 miles or so, pull in for gas and normally put in 4.5 or 4.6.....now the first 1200 miles of the trip, at 150 miles I am putting in 3.9-4.1....ran a LONG stretch of170 miles and added 4.6 gallons...My rough calculations are that I just jumped to about 40mpg! So, How did this happen?? was it the something with messing with the fuel pump? was it the new spark plugs (as far as I know, they were still the factory stock, but don't know for sure)? Was it the clean air filter? Generalized service? They only DID the 20K by the book!!! Nothing on the paperwork indicated otherwise!!! I am NOT going to complain about the sudden boost in gas milage, however...... oh, was thinking maybe the PCIII lost its map....but it is NOT running hot, and same or LESS decel popping...in fact, I think it was LESS!!

So, anyone with the answers to this mystry? SCOOBY DOO....WHERE ARE YOU??!! :roflmao:

Hmmm, doesn't make sense to me either. Sometimes you'll see a very slight improvement after a service, but not very often that much. Did they replace plug wires too? Just taking a stab but perhaps you were getting a weak spark or had a poorly grounded plug and were using more gas in the process. If you lost your map I'd suspect that you'd feel something or at least see the temps coming up.

Then again, maybe the Power Commander fairy came during the night and did some remapping

Have fun on the ride, and if you can bring back pictures!

I would be VERY happy with a PC fairy coming!! At some point, would like to get more info on the Termonal Velocity "tuning on the fly" thing.....there are a few posts, but I will need more info (like tuning each jug, and how well it actually works.....want to get true duals first tho! As to pics, with the kind of traveling that I was doing over the last 2 days, took NO pics, but that should change over the coming days!! As to the plug wires...no indicators of wire changes....only plugs, fluids and routine service. There for a second, I was almost wondering if I had a LARGER TANK....but that still doesn't compute for the number of gallons added and the miles ridden.....nope...that isn't it......Only thing I can think of is that MAYBE.....one of the 2 plugs was iffy...ran well enuf to pass service, but was hurting with the burn?? Chuck even checked a plug and we agreed (a week ago) that I was running just a bit rich...not huge, but a bit...soot on the first thread of the plug, and some soot on the exhaust pipe..... again, NO other changes made.....??!!! won't complain, but still a curous thing.

ya know, it is amazing the things that happen when i wave my hands over an internal compustion engine!!!:roflmao:

sooooooo how was your mileage on the trip????

well, hard to tell for sure....looks like for the most part, stayed up around the 40 mark......hard part was on the fly coming home.....was able to AVERAGE (including stops, 40mph crosswinds, rain, and HEAT) 70mph for 1600+ miles.....think that over 80, my milage goes to crap.....75-80 pretty good/acceptable.....75 and below......am running around 40mpg. This is ball park...didn't really keep tally of numbers so can not tell for sure. Is all approx based on quick glance at miles and gallons at the pump each time! Still running better then before I left, so the question arises....what will happen now that I am "full time" back in texas??!!

well, for starters, for the next few weeks your gonna sweat your buns off!!

that ain't no joke!:fight: uke: Still doesn't answer how the MPG will fair....I am wondering if (2 things here....) 1. altitude effect.....and 2. did they "reflash me" during service and not charge me? almost afraid to go check on THAT one......everything is running great so can't complain...and if they DID reflash me, don't want to have to pay for it either! :devil:

i would just ride it, and keep a check on things.....check plugs, exhaust..weekly.

i wonder if your bike was on a recall list for a flash??? just grabbing here....

come on you two it's only warm here here in TX , 108-115 today with the heat index
AFN you could have just cleaned it out by running the hwy , like you said your bike run's at the speed's you posted sound's like mine 03 E Glide standerd seems to run & feel better about 75-80 range , any engine will make a build up just running around town , then take it out for a joy ride like you did & wow your all cleaned out

UPDATE: well, sorta, but not really! So, got back from Sturgis and have done a little bit of riding but not much...mostly due to work and family time constraints. I JUST put in my first tank of gas since returning from the trip.....had fueled up in Austin and made the run at about 80mph....then doing a bit of work commute riding. This tank got 36.9mpg. STILL higher then when I left, and now the whole tank is what I would call a "local Texas" ride....Austin is only 60-80 miles from home (dpending on where you measure to/from). Still running with MUCH less decel pop.....now only time will tell what the actual mpg does while getting back into "normal routine riding"......

thanks for the update.....