I'm trying to educate myself about my bike and begin doing the service and upgrades myself, so any help you can provide would be well received. I've started going through the service manual.

I bought an 07 Fat Boy last year that had already had the 103 Big Bore kit with the 255 cam installed with VH Big Radius 2:2, an after market breather and the stock ECM was remapped with a Stage 1 download. Before I took delivery of it, I had them install a Screamin' Eagle Heavy Breather. They said it would not need to be remapped for the new breather.

I began to notice the bike had bad pop on decel, and it would also pop when cruising in the upper ranges of 3rd, 4th and 5th gears. The dealership where I bought it is 150 miles away, so I had a PCV installed by a local bike mechanic who used to work for HD and said it would smooth it out in all the gears and take care of the bad pop on decel.

The PC V did exactly as he advertised. The bike runs great, sounds great, has more power and I can ride in any gear at any range and it purrs like a kitten, but it gets horrible mileage now. From over 40 to 32! We were going between 70 and 75 much of the way on country roads. I've read on this site and others that is what happens when the bike is tuned for performance over MPG, but I just told the guy I wanted the bike smoothed out and to get rid of the pop. My friend gets 39 on his '10 Street Glide with a 96 and nothing but 2 into 1 HD pipes.

Should I just have gone to my local HD shop and had them remap the stock ECM to recognize the SE Heavy Breather instead of buying the PCV? I want to put a Mustang solo seat on and I'm not sure it will fit with way the ECM, plug and cables had to be relocated to accept the PCV module and cables. the bike must be running really lean, and I don't want to burn my motor up. I bought the 2 year HD warranty since I was getting a used bike, but I know the PCV could void that warranty.

I plugged in my laptop to the PCV to see which mapping he had used. Screenshots for each cylinder are attached. My bike is a 2007. He used a mapping for a 2009, but the configuration seems to be correct UNLESS the 103" big bore kit does NOT come with flat top pistons.

2009 Harley Davidson Softail *Advanced Map*
Vance & Hines Big Radius 2:2 Exhaust
Screamin’ Eagle 103” flat top pistons
Screamin’ Eagle 255 Cams
Screamin’ Eagle Air filter
Stock ECM

 

The screenshot tables are unreadable...too small. I suspect your AFR's are going to be on the rich side in the cruise range,

 

You can always get the AutoTune for the Power Commander V.

 

highlight the 10-15-20 % throttle positions, from 2500 down to 3000 rpm and reduce each # in each cell by 10-15 ....and retry, that will reduce fuel consumption AT CRUZ ONLY ... now if you are banging on the throttle every time you leave off ....well your mpg will fall ...!!! then you need to start reducing the whole map by 5-10 points !!! autotune will not save you gas ...only reducing the AFR in autotune or in the fuel table will do that !!! take fuel out ...when problems come up (popping on decel, loss of power ) put some back !! you must keep track of what and where you change the map !!! this is all call TUNING !!! you must tune the "BASE" map you where provided !!! no two bikes are alike !!! plus now you basically have a fuel injected bike that will need to be tuned like a carbureted bike and altitude will affect everything also ....if you are higher than where that base map was made ...it will tend to run richer and the higher in altitude you go it will get even richer !!!

 

thanks for the input, springers4ever! Sounds like it can get pretty complex. I called Power Commander support just to see what they would say and of course they said it a performance product not a fuel mileage product. He said there are a multitude of factors that could explain my mileage drop of which some, or most, are caused by me.