100% Counterbalanced
Seasoned HDF Member
Joined: Mar 2010
Posts: 38,605
Likes: 6,438
From: Honah Lee
Actually for those who do not understand dynamic balancing, No twin that the connecting rods share the same crank pin is going to be 100% balanced. The reason the TCb is close is it has two lobes. One for each cylinder. However, it's still a little coarse with it's solid mounted engine. The first cylinder fires, the second (rear) cylinder fires 315° later, then there is a 405° gap until the first cylinder fires again.
The reason Harley new motor is out is it only has one balancing cam that the two pistons share..It does have a rubber-mounted engine, transmission, drivetrain rear wheel isolated from the frame.
The reason Harley new motor is out is it only has one balancing cam that the two pistons share..It does have a rubber-mounted engine, transmission, drivetrain rear wheel isolated from the frame.
Last edited by Jackie Paper; Aug 30, 2017 at 01:05 PM.
Seasoned HDF Member
Joined: Oct 2010
Posts: 12,228
Likes: 7,806
From: Along the shoreline in SW FL
There's always metric sewing machines like a Goldwing..if ya want buttery smooth.
My Shovelhead never bothered me at highway speed. Let's you know the bike is alive!
Current hard mounted Evo Softail doesn't bother me either..it's not nearly what my Shovel was like, still gives a little buzz at highway speeds. Doesn't exactly "rattle your teeth"...just a little buzz. Part of the allure to me.
My Shovelhead never bothered me at highway speed. Let's you know the bike is alive!
Current hard mounted Evo Softail doesn't bother me either..it's not nearly what my Shovel was like, still gives a little buzz at highway speeds. Doesn't exactly "rattle your teeth"...just a little buzz. Part of the allure to me.
Road Master
Joined: Apr 2017
Posts: 832
Likes: 1,173
From: Wisconsin
Previous bike was a Victory CCT with the Freedom 106, which is VERY balanced.
I kind of liked that -- no teeth a-jigglin' at idle.
But, the '17 M8 is very tolerable at idle. Not as smooth as the F 106 but still nice.
Anyone else notice that when the M8 gets "hot"at idle and the rear cylinder cuts out (per
design) it vibrates much more like the twin-cams?
I kind of liked that -- no teeth a-jigglin' at idle.
But, the '17 M8 is very tolerable at idle. Not as smooth as the F 106 but still nice.
Anyone else notice that when the M8 gets "hot"at idle and the rear cylinder cuts out (per
design) it vibrates much more like the twin-cams?
Seasoned HDF Member
Joined: Jun 2015
Posts: 8,055
Likes: 8,080
From: Canada
Agreed, I was just on mine, great choice of words!
Road Captain
Joined: Jan 2013
Posts: 546
Likes: 606
From: Out West
Could be wrong, but here is my understanding.
The counter balance effect is more relevant to efficiency and power delivery than vibration issues the rider feels.
Vibration has a substantial power robbing effect, and as long as the HP consumed to "run" the counterbalance/s then it's a net gain. Much like a dragster consumes 500HP to turn the blower, but it puts 1500HP into the system- a 1000HP gain.
The improved efficiency also helps with emissions compliance, fuel efficiency, oil life, and noise pollution.
The counter balance effect is more relevant to efficiency and power delivery than vibration issues the rider feels.
Vibration has a substantial power robbing effect, and as long as the HP consumed to "run" the counterbalance/s then it's a net gain. Much like a dragster consumes 500HP to turn the blower, but it puts 1500HP into the system- a 1000HP gain.
The improved efficiency also helps with emissions compliance, fuel efficiency, oil life, and noise pollution.
Seasoned HDF Member
Joined: Aug 2009
Posts: 9,243
Likes: 3,267
From: west Michigan
My '73 750 Yamaha had counterbalancers in the engine; it's nothing new.
The engine in my '76 GoldWing WAS as smooth as a sewing machine, and strong. That was a damn good motor.
The engine in my '76 GoldWing WAS as smooth as a sewing machine, and strong. That was a damn good motor.
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Seasoned HDF Member
Joined: Jun 2015
Posts: 8,055
Likes: 8,080
From: Canada
Forced induction on any internal combustion engine does all of the above but a balance shaft is mainly for occupant comfort. I know my wife would rather ride an M8 than my shovel head but loves the sound of the shovel head. She would be a buyer of a new "soft tail" for sure at the age of 46.
Road Master
Joined: Jun 2016
Posts: 749
Likes: 287
From: Detroit area
On the other hand, the engine on its rubber mounts has a natural frequency (resonance) of about 52 Hz, which means 3100 rpm. Which is conveniently right at highway cruise speed. And that's a high-energy buzz that you feel throughout the whole bike which turns your hands, feet, and *** numb. I could do without that.