I have a question for those who have the Stage 4 upgrade and it has to do with the range of the ride: What does the Stage 4 upgrade do to fuel consumption? The cost of fuel is not the issue, it's how often I would have to stop on road trips to fill the tank. I have a 2020 Road Glide Limited with a Stage 2 upgrade on my 114. I enjoy long distant rides and can travel around 160 miles before I have to stop for fuel. I would enjoy the extra horsepower but not if I have to tether myself to the nearest gas station.

 

Can`t speak to M8 but I added cubes / cams / compression to a T/C and the mpg did not change
42 +

 

That range you have now sucks. You need to have a good dyno tune, no matter what "stage" you have if you want optimal range.

I have a Fuel Moto 128 big bore kit, aftermarket cam, etc., etc., and a PowerVision tuner that is better than any Harley stage 4. I had Jamie at Fuel Moto dyno tune it, and fully loaded on long trips I regularly average 36-38 MPG. I do not ride slow and easy. So, do that math with a 6 gallon tank.

We have hyper-miled across long stretches between stations in NV, and UT, and can get 41-42 MPG keeping it around 60 MPH.

 

I did a 131 upgrade on a 117 and my gas mileage dropped by about 4-5 mpg. You should still be able to do 160 miles between fill ups. I’ve run stage 2 m8’s routinely over 200 miles in between gas stops.

 

Stage IV-132hp/138tq and I consistently get well over 200 miles to a tank. On the highway at 75mph, i get 42mpg. Anything over 80mph and fuel consumption increases dramatically.

The biggest factor in gas mileage is your right wrist!

 

Stage 4 on a 103". Punched out to 110". Fuel mileage dropped 5-mpg. I can go 160-miles on a tank.

 

2012 twin cam
107” big bore
ported heads
Redshift 575 cams
Thundermax ECM

I’ve never payed much attention to my fuel consumption on back roads cruising at 70mph or less. I want to say I can go about 200 miles on a 6 gallon tank. Where I have payed attention was the results of doing a 1000 mile iron butt ride last year. It was all interstate traveling at 80 to 85mph all the way. My comfortable range at those speeds is 140 miles max. That still leaves a half to a quarter gallon of reserve fuel depending upon hills and wind. More powerful build and fast speeds eat fuel. There’s no getting around that.

 

If I didnt get on the throttle, I had no change. That said figure 5 mpg drop

 

Running a straight up SE Stage 4 128", I get on average 42mpg on a trip running cruise @ 77mph.
I average 32 to 35 mpg riding around the backroads hammering on it fairly often.
This is always better than my old 2008 Twincam 96" Streetglide.
Slightly less than my old 2018 Heritage 107"

 

same thing here 45 with my 117 , 37 with my 131 but it sure is fun