We are 3 model years into HD’s Milwaukee 8 engine platform with 2017 being the first year for the M8.
The engine displacement options for M8’s are 107, 114, & 117. So starting with 2019 HD made an even bigger change to their touring lineup to distinguish models unlike prior years (except CVO’s) Now standards have the 107, the specials get the 114, and the CVO’s getting the 117.
The MoCo claims the M8 was an all new engine from the ground up, yet they havent strayed from the much loved and hated TC in regards to looks or basic V-Twin design a whole lot. The best part is HD learned from their mistakes with the TC, and built the M8 to be a better, more powerful, and cleaner version of the TC. Well that hasnt come without its own issues. So now lets take a look at some of the growing pains the M8 has endured so far.
Loose valve seats
Oil pump failure
Trans to Primary fluid transfer
Rocker box leaks
Now these arent all the small issues some M8 owners might see, these just happen to be some of the larger issues that are getting noticed on forums and on Facebook HD groups (I rEaD iT oN tHe InTeRnEt, sO iT mUsT bE tRuE !!) and some that Harley themselves have had to address thru warranty. I debated on listing complete engine failures as well, but it seems most have come from the Oil issues, as well as owners not noticing and addressing an issue right away.
Some of these issues are being addressed by Harley techs themselves like a popular Youtuber John Maxwell, I will link his channel here. He works at a dealership in GA, and states most of the issues the internet is freaking out about haven’t been widespread, and his dealership has seen very few of the issues come thru their shop so far.
With all this negativity I have talked about with the M8, should you even consider buying an M8 powered bike or should you stick with your TC or Evo powered bike? You need to remember the TC had a lot of growing pains, and has been around a long time, with my opinion of the 14+ 103’s being the best version of the TC engines. Like with any machine its going to have issues, and most of these M8 issues will be covered under your warranty, but only time will tell how epic the M8 engine will be.
Like with anything, do your research, get verification from the dealership that possible issues have been addressed with that used bike, and I say go for it, I only have 1k miles on my 114 so far, but it has been a complete blast so far!