Cobra 909 Slip Ons

[JTJersey]

I'm looking at these Cobra 909 slip on's hoping for a bit louder and deeper sound than OEM. I'm hesitant to buy into the HD pipes because a lot of reviews say they're no louder than stock. These pipes have been mentioned a few times here, but the only reference to them I could find was from 2016. Probably not relevant to a 2021 M8. In those previous posts several people commented that no tune was needed, which I have doubts about. At the risk of this being repetitive does anyone have any info on these for the M8 motors?

 

[Jack Klarich]

JT, rest assured the M8 will do fine with just an exhaust change

I tried a few combos on my 17 and had no problems

When u change the intake and exhaust you might have some problems

 

[JTJersey]

JT, rest assured the M8 will do fine with just an exhaust change I tried a few combos on my 17 and had no problems When u change the intake and exhaust you might have some problems

Welllll, I did put this Cobra Aircleaner with K&N filter on several months ago.

 

[Jack Klarich]

Welllll, I did put this Cobra Aircleaner with K&N filter on several months ago.

View attachment 108372

Despite what many say about the M8, it does NOT run lean from the factory

Could it use more fuel added after changing the air and the exhaust? Sure thing

 

[rhino 2]

One of the things I learned from monkeying with cars and bikes since the early 60’s…

One added part begets adding another added part to enhance the last added part you added and so on…That’s why at this stage of my life my 2019 Triglide is staying stock.

 

[JTJersey]

One of the things I learned from monkeying with cars and bikes since the early 60’s… One added part begets adding another added part to enhance the last added part you added and so on…That’s why at this stage of my life my 2019 Triglide is staying stock.

Absolutely right. Learned that back with my '59 Pan. Change one thing and rearrange 4 others to make it work. Guess the more things change the more they stay the same.

 

[Jack Klarich]

JT, read here what D K Customs says about the 21 M8s

 

[JTJersey]

Despite what many say about the M8, it does NOT run lean from the factory Could it use more fuel added after changing the air and the exhaust? Sure thing

You think it would run any better or worse without a tune? If I take it to the dealer they'll tune to EPA specs. Closest dyno tune shop is 2 hours from me. Don't want to screw up my motor, just want it to sound a bit better.

 

[JTJersey]

JT, read here what D K Customs says about the 21 M8s

I watched that vid from DK several times and as far as I can tell he's saying NO, it doesn't need a tune for the '21 M8. It could run BETTER with one, but not required. All those charts are meaningless to me. I just want it to sound better and not damage my motor.

 

[Jack Klarich]

You think it would run any better or worse without a tune? If I take it to the dealer they'll tune to EPA specs. Closest dyno tune shop is 2 hours from me. Don't want to screw up my motor, just want it to sound a bit better.

I think it will run fine from my experience with mods to my 17 Freewheeler, I have not done any critical mods to my 21 other than a catch can on my head breather bolts

The Dyno charts show that the M8s are not running lean, that is a good thing

even after an air cleaner and exhaust change

I have heard those cobra mufflers on the road, they sound damn good

 

[New Orleans Kevin]

I think it will run fine from my experience with mods to my 17 Freewheeler, I have not done any critical mods to my 21 other than a catch can on my head breather bolts

The Dyno charts show that the M8s are not running lean, that is a good thing

even after an air cleaner and exhaust change

I have heard those cobra mufflers on the road, they sound damn good

I've not put my 2021 on a dyno, but have put slip-ons, ( Klock Werks 4.5's with performer baffles) and DK 606 Air Cleaner with Transformer EBS and catch can and my Triglide has run damn good for the last 5 k. After warranty , it will be time to put a camchest kit in.

 

[rhino 2]

Here’s how it usually works you put some performance parts or changes on a vehicle everything is running fine” Then after a few hundred miles of riding you start to get this nagging feeling that I could probably get just a little more performance and add something else to enhance the last thing you added’ And that’s human nature when adding enhancements to personal type vehicles..

Ie; Motorcycles’ Trikes ‘ATVs ‘Sports cars ‘ Etc. Etc…

The expert? says you don’t need anything else’ But who always believes the expert ..If? They did believe the expert they would leave it stock….But it’s the part of the brain that nags at you and says…I can do it better....

 

[JTJersey]

I just want it sound a bit louder. The bike runs great. I've never experienced any heat issues in 9000 miles, even on 94 degree days in traffic. It's just a little too quiet for my taste.

 

[rhino 2]

I just want it sound a bit louder. The bike runs great. I've never experienced any heat issues in 9000 miles, even on 94 degree days in traffic. It's just a little too quiet for my taste.

I judge the loudness of my pipes when I’m driving down the street at around 30 miles an hour and somebody’s walking a dog on the sidewalk and the dog turns around and wants to rip my foot off then I know that the pipes Are just right …..

 

[JTJersey]

In their excellent video on tuning for '21 M8 motors after an exhaust and air cleaner change DK Custom says 14.5-15 to 1 is ideal cruising, while I'm finding Harley saying that 12.7 - 1 is the ideal although they don't say "cruising", just cite the number. Now I know HD will not exactly always tell the whole truth or may have ulterior motives, but I trust DK and see no reason for them to mislead anybody. Bad for business, but would someone have a bit of clarification on this for me?

 

[Jack Klarich]

In their excellent video on tuning for '21 M8 motors after an exhaust and air cleaner change DK Custom says 14.5-15 to 1 is ideal cruising, while I'm finding Harley saying that 12.7 - 1 is the ideal although they don't say "cruising", just cite the number. Now I know HD will not exactly always tell the whole truth or may have ulterior motives, but I trust DK and see no reason for them to mislead anybody. Bad for business, but would someone have a bit of clarification on this for me?

12.7 would be cruising AFmixture, for power . think this is a bit too rich for my liking and a bit harder on fuel consumption

Keeping in mind there is a lot of things to consider, air cleaner, exhaust, air leaks in the intake tract, leaky injectors and type and octane of fuel

 

[Jack Klarich]

JT, take a look at these numbers. This was my 17 Freewheeler @ D K Customs

I volunteered my M8 to their dyno, it was a blast meeting Kevin and crew that day

https://www.dkcustomproducts.com/milwaukee-eight-dyno-charts-other-interesting-info-dk-m8-rpt.htm

 

[Notgrownup]

I have Fuelmoto Jackpots with a welded lollipop for back pressure… they sound great. They were a bit loud and had a droning sound to me. I simply welded a heavy duty 2” washer with a little tab to the end of my baffle and coils, Torque added, sound is A bit mellowed, perfect for touring. If I want it louder I could just bend it out. I tried a few angles and like this was the best for me.