I'm happy to find out the mpg with the mighty 131ci on this link.I have the kit with many more modifications/upgrades. I will put it on my 2019 Harley-Davidson Heritage Classic FLHCS 114 Softail. The strange thing about the Stage IV 131ci Kit is that some Harley-Davidson Dealerships say it's not legal in California, and some say it's legal. This is in the San Francisco Bay Area. Thank you.

 

Have they fixed the valve spring issue with the CNC heads? Buddy’s 117 build recently dropped a valve due to valve spring failure on CNC heads for 2017 107. He does not dog his bike and doesn’t have a lot of miles.

 

Two at local dealer with those heads and failed valve springs.

 

Appreciate the info in this thread. I similarly love my bike and plan to keep it rolling...

I should end this year close to 50K miles and see close to 70k by the end of next year if things go as planned. At that point I’ll be looking at a rebuild if for nothing less than proper hygiene.

Should have a good idea of the 131 experience by then (performance, reliability, issues, etc.). I won’t be looking to go as big as possible when the time comes, just looking for a reasonable bump in performance to go along with a solid rebuild to take me confidently through the next 70k miles.

Question I have at the moment is whether there are advantages / disadvantages re: the complete crate engine vs. the kit. I’m on a 2018 CVO Street Glide w/ 117.