Milwaukee Eight Big Bore Kits
Novice
Joined: May 2018
Posts: 15
Likes: 1
From: Farmville, NC
Not trying to change the subject but thought I would throw this out there. I have harley stage iv on my new heritage and its incredible. Only problem is auxiliary lights and fender trim keeps getting loose from the pressre I guess. Im running vance and hines big radius pipes, and the horsepower cam. Its a beast. I was initially concerned about the high revs needed to access the power band. I have no more concerns. Its a great package. You access the power band quickly. Its not so torquey that you break the tires loose but within approximately a second your in the power. Its works great for me. I think its easier to understand the dyno charts when you are actually feeling it on the bike. I went from stage II torque cam (which was a beast in itself) to the stage IV with the power cam so I feel like I have a pretty good comparison. If I had to do again I probably would have stopped at a stage III. Im not sure there is much of a difference. With the stage IV, im pretty confident that the harley package delivers a lot more power than the bike can handle. Im pushing the rev limit on gears 1-3 and chickening out in 4th. The bike gets too sketchy for my taste around 120. I would be curious of your opinion of an after market stage kit. I have seen some of the numbers. I would like to know if its ride able.
Good luck
Good luck
HD EFI Guru
Joined: Jan 2008
Posts: 4,462
Likes: 4,718
Hey Steve
The Revolution Performance 124" big bore kit for the M8 107 does not require case machining, at least according to their website. They are using 4.250 all aluminum NSC plated cylinders. I have no experience with NSC plated aluminum cylinders on a Harley, but would appreciate your opinion.
The Revolution Performance 124" big bore kit for the M8 107 does not require case machining, at least according to their website. They are using 4.250 all aluminum NSC plated cylinders. I have no experience with NSC plated aluminum cylinders on a Harley, but would appreciate your opinion.
Stage II
Joined: May 2018
Posts: 2
Likes: 0
From: California
What I can say is that I have our new prototype 4.250" cylinders sitting here and that is as big as I feel you can go without machining the cases with a steel liner in them! I would never try it with AL liner it is just too thin of a section of material down towards the bottom of the cylinder. You need to machine the cases to provide enough material thickness if your going to do all AL.
Tourer
Joined: Sep 2012
Posts: 497
Likes: 50
From: CA
@Patrick Eubanks
Did you install your SE kit? Asking about 3rd party stage kit numbers? Someone posted: I did the Fuel Moto 124 on my 18 CVO Roadglide runs great, Made 144hp/138TQ.
Did you install your SE kit? Asking about 3rd party stage kit numbers? Someone posted: I did the Fuel Moto 124 on my 18 CVO Roadglide runs great, Made 144hp/138TQ.
Advanced
Joined: May 2018
Posts: 52
Likes: 27
From: Berlin, Germany
What I can say is that I have our new prototype 4.250" cylinders sitting here and that is as big as I feel you can go without machining the cases with a steel liner in them! I would never try it with AL liner it is just too thin of a section of material down towards the bottom of the cylinder. You need to machine the cases to provide enough material thickness if your going to do all AL.
Cruiser
Joined: Sep 2017
Posts: 126
Likes: 26
From: Indy
I want to be just under 11:1 and use the TTS 200 cam.
HD Forum Stories
The Best of Harley-Davidson for Lifelong Riders
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
Southpaw Super Glide: A Left-Hand-Drive 1979 Harley FXE Built to Fit the Rider
Verdad Gallardo
HD EFI Guru
Joined: Jan 2008
Posts: 4,462
Likes: 4,718
We have run the 200 cam with compression ratio's up to 11.5:1 and it's fine. We do recommend 11:1 for that camshaft, so do not worry about being under 11:1 due to the camshaft.
On the 117 big bore for the M8 using CP pistons the difference between 10.75:1 compression and 11.1:1 compression is installing a .045 head gasket for 10.75 and a .030 head gasket for 11.1. Im not sure how it works out on the 120 and 124 big bores.
The M8 seems to like high cylinder pressure. The 114 option in the Softail line is 10.5:1 compression and it uses the same cam as the 107 with 10:1 compression which closes the intake valves at 1 degree abdc. This works out to a CCP north of 225 psi.
The M8 seems to like high cylinder pressure. The 114 option in the Softail line is 10.5:1 compression and it uses the same cam as the 107 with 10:1 compression which closes the intake valves at 1 degree abdc. This works out to a CCP north of 225 psi.