Milwaukee 8 Engine Problems
Road Master
Joined: Jun 2015
Posts: 806
Likes: 1,513
From: Bloomington, IN
My 2020 CVO Road Glide has 136,000 miles and has been flawless. That's with 7000-8000 mile motor oil changes.
Anything can go wrong at any time, but my twin cam was a nightmare compared to my M8.
Anything can go wrong at any time, but my twin cam was a nightmare compared to my M8.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,899
Likes: 8,006
From: poway
Lots of theories on why they had to add a vent after all these years. Another is with the change of starter in 2007, less venting through that. Another, is engines got bigger and hotter, and this probably materializes more on touring bikes, cause they get rode more. I kinda suspect it all adds up. Probably vented a little through starter, than took that away and hydraullic clutch made it worse.
103 TC had hydraullic clutch, no vent, and no venting through starter. Which isn't a lot but some.
I have heard there was some issues before M8. I wouldn't be surprised there was, and most people who change it every 5k don't notice it, if just a little. Fluid levels have changed in the 6 speed tranny before the M8s too. I wonder why.
103 TC had hydraullic clutch, no vent, and no venting through starter. Which isn't a lot but some.
I have heard there was some issues before M8. I wouldn't be surprised there was, and most people who change it every 5k don't notice it, if just a little. Fluid levels have changed in the 6 speed tranny before the M8s too. I wonder why.
On 5 speed there wasn't any venting through the starter.. Don't know where you got that but if there was, there'd be a leak..
You are correct about the hydraulic clutch being a part of the issue on M8.. There have been some 6 speed CVO TCs that had this issue.. HD changed the trapdoor bearing on M8s VS TCs.. To help. Also IMO the first gear rattle fix helped to force oil through the trapdoor bearing to cause the issue..
BTW
2017 RK 53000 miles, stage 2. Did replaced lifters with Hylifts at 2K. It needed the primary vent at 40K.. Had the front heat shield crack.. HD updated the shield. No breather mods and no oil dripping from the AC. Bike runs like a top.. Was broke in correctly. 41-45 mpg.. Still has the original oil pump.
I do have a bud that bought a 2017 FLTR used that ended up having a blown base gasket.
Last edited by Max Headflow; Sep 10, 2023 at 07:30 PM. Reason: Still has the original oil pump.
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,272
Likes: 3,684
From: backwoods
I wonder why they managed to get by without a vent on primary all these years? Are we saying it was the hydraullic clutches fault?
I heard heard some claims it has been going on for a bit. Maybe as motors got bigger and emmssions got stricter, and engines got hotter. I do not know.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,899
Likes: 8,006
From: poway
There was probably a small amount through the jackshaft. I am not the one who came up with the idea. Not saying there was a lot. But how much was passing through the shaft for the clutch, granted the tranny has vent.
I wonder why they managed to get by without a vent on primary all these years? Are we saying it was the hydraulic clutches fault?
I heard heard some claims it has been going on for a bit. Maybe as motors got bigger and emissions got stricter, and engines got hotter. I do not know.
I wonder why they managed to get by without a vent on primary all these years? Are we saying it was the hydraulic clutches fault?
I heard heard some claims it has been going on for a bit. Maybe as motors got bigger and emissions got stricter, and engines got hotter. I do not know.
Primary originally vented through the main shaft where the clutch pushrod goes. You really need to look at he differences between the layout of a cable versus hydraulic clutch to see what is going on..
As you run motor leaner, you generate more heat simply due to the fact that lean mixtures burn slower.
Stellar HDF Member
Joined: Jan 2017
Posts: 2,673
Likes: 2,078
From: Massachusetts
[QUOTE=Max Headflow;21377312]jackshaft - if you are discussing the starter jackshaft, there is no way it can pass oil into the starter. If it leaks, it will leak out the coupling between the primary and starter. I think that the original poster may have been dealing with a TC 6 speed. It does not apply to 5 speed TCs. IMO looking at his issues, he had a plugged tranny vent.
Primary originally vented through the main shaft where the clutch pushrod goes. You really need to look at he differences between the layout of a cable versus hydraulic clutch to see what is going on..
As you run motor leaner, you generate more heat simply due to the fact that lean mixtures burn slower.[/QUOTE
]
Wasn't some blame of the transfer problem, placed on the fact they Harley went to a narrow primary for the touring bikes as well?
Primary originally vented through the main shaft where the clutch pushrod goes. You really need to look at he differences between the layout of a cable versus hydraulic clutch to see what is going on..
As you run motor leaner, you generate more heat simply due to the fact that lean mixtures burn slower.[/QUOTE
]
Wasn't some blame of the transfer problem, placed on the fact they Harley went to a narrow primary for the touring bikes as well?
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,272
Likes: 3,684
From: backwoods
I have not had a need to work on my hydraullic clutched bike. Hopefully I don't get experience for awhile.
Seasoned HDF Member
Joined: Mar 2021
Posts: 18,272
Likes: 3,684
From: backwoods
Never thought of that. You limited lows, and then I believe all touring bikes, and not sure about the rest went to a small primary in 2016, I have been told. I did notice less oil in the 2016 primary. Though my first guess was they figured it would gain it from tranny, and over 5k, wouldn't be a problem. Though the manual does have longer service intervals, and some follow it.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
7 Surprising Harley-Davidson Products that Are Not Motorcycles
Verdad Gallardo
8 Best Harley-Davidson Motorcycles Ever
Pouria Savadkouei
10 Worst Harley-Davidson Motorcycles Ever
Pouria Savadkouei
Killer Custom's Jail Break Is The Breakout That Refused to Blend In
Verdad Gallardo
Crazy Bunderbike Build Looks Amazing, But Is It Impossible to Ride?
Verdad Gallardo
Harley-Davidson Reveals Super Cool Cafe Racer Concept
Verdad Gallardo
Engraved Rebellion: Inside Bundnerbike's Glam Rock II
Verdad Gallardo
10 Motorcycles You Should Never Buy
Joe Kucinski
10 Things Harley-Davidson Needs to Fix in 2026
Verdad Gallardo
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,899
Likes: 8,006
From: poway
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,899
Likes: 8,006
From: poway
Venting, not oil movement. Not a lot, but some. through the jackshaft. Enough to help, I don't know. But what has changed? Why do you need the vent now? Bigger hotter engines. It doesn't do to everybody. Other theory I heard is it happens more in touring bikes cause they tend to get rode more, and longer distances. Nothing else, that is why you probably tend to seem more issues in touring bikes.
I have not had a need to work on my hydraulic clutched bike. Hopefully I don't get experience for awhile.
I have not had a need to work on my hydraulic clutched bike. Hopefully I don't get experience for awhile.