Why a single cam?

[mp]

Sounds like all bad reasons to use a less efficient design on motorcycles that are well over $20,000 for non-CVO models.

[Matt C]

I'm gonna guess 'simplicity' and money. 4 valved heads are also superior (air flow wise) and take
allot less lift. Lower spring pressures/lighter valves overcomes some of the ails of the EVO v/t.

These things will have potential to take it to the next level, those heads are going to be kick-ass.

[Durwood]

I'm gonna guess 'simplicity' and money. 4 valved heads are also superior (air flow wise) and take
allot less lift. Lower spring pressures/lighter valves overcomes some of the ails of the EVO v/t.

These things will have potential to take it to the next level, those heads are going to be kick-ass.

I agree 100% Matt.

[glens]

They made a big deal about reducing the number of moving parts to reduce parasitic drag too.

Probably more like wanting to reduce the number of parts to decrease assembly time and increase assembly consistency.

I was curious about the term "parasitic drag" so looked it up.  Evidently it's an aeronautical term and pertains to air friction.  Not to be the terminology police or anything, but in this case it would be "parasitic friction" or generally "parasitic losses".  Have a look at page 3 of http://energy.gov/sites/prod/files/2014/03/f11/merit08_fenske.pdf for something very interesting.

[Don D]

I'm gonna guess 'simplicity' and money. 4 valved heads are also superior (air flow wise) and take
allot less lift. Lower spring pressures/lighter valves overcomes some of the ails of the EVO v/t.

These things will have potential to take it to the next level, those heads are going to be kick-ass.

Yep   
But MOCO is already playing a supply game on the heads.

[Ohio HD]

All you have to do to get heads is....  buy a bike,          or, get in business with another aftermarket that bought a bike for reasons other than the heads.

[Durwood]

All you have to do to get heads is....  buy a bike,          or, get in business with another aftermarket that bought a bike for reasons other than the heads.

[PoorUB]

Sounds like all bad reasons to use a less efficient design on motorcycles that are well over $20,000 for non-CVO models.

Who said it is less efficient? Looks like the push rods are straight on, better than the TC or Evo, less side loading of the rocker arms and lifters. Less moving parts, more valves, more flow at lower valve lift. In theory it should be a good deal. Now give the M-8 a couple years in the street to see how John Q-Public can find ways to destroy it to see if the theory holds up. It looks like a good engine, but time will tell.

[wfolarry]

The best thing they did was go to a single cam. The chain drive makes it easier to keep it quiet. There's a lot of improvements there that you're not seeing that will show up down the road as they start coming apart for upgrades.
If I was to improve on the 45* V Twin I would have done it the same way. There's a lot of potential in that motor with a lot less stress on it than those damn twinkies.

[FSG]

    there's lots of little things

the bevel/countersink on the inner cam bearing position

then clearing of the lifter bores for the cam lobes, easy when only a single cam

1st thing I'd be doing is measuring the bottom of lifter bores (current max cam lobe lift) to see what it is now and how much more could be taken off the bottom for bigger cams if needed

Go to a gear drive setup with an adjustable +/- 10 Deg Cam Gear, S&S, Andrews, other.   

[CVOThunder]

SO who's gonna be the first to make a set of 4 valve heads for the twin cam? Is it possible and wonder how it would look. Probably have to do the same to the covers but would they fit in the frame.

[JW113]

Four valve heads.
Push rods & rocker arms.

[attach=0]

Chain drive single cam.

[attach=1]

Gee, wonder where they got all that?

[attachimg=3]

History repeats itself.

-JW

[FSG]

History repeats itself.

   I had a CX Shadow 

[PoorUB]

SO who's gonna be the first to make a set of 4 valve heads for the twin cam? Is it possible and wonder how it would look. Probably have to do the same to the covers but would they fit in the frame.

Seems to me it was done already, about 15 years ago.

[mp]

Sounds like all bad reasons to use a less efficient design on motorcycles that are well over $20,000 for non-CVO models.

Who said it is less efficient? Looks like the push rods are straight on, better than the TC or Evo, less side loading of the rocker arms and lifters. Less moving parts, more valves, more flow at lower valve lift. In theory it should be a good deal.

I was referring only to the chain-driven cam being less efficient.  The new engine looks far better than the Twin Cam in most every way.  Of course, I recall a lot of people thinking the Twin Cam looked better than the Evolution and we all know how that worked out.

[CowboyTutt]

A 4 valve hemi conversion was available, but it never really delivered the performance advantage it promised at a practical price point.  http://thekneeslider.com/4-valve-hemi-heads-for-harley-big-twin-engines/ There just wasn't enough interest and development time for it.  Two valve technology meanwhile really took off afterwards and 4 valve head conversion development stalled out. 

Its why I keep suggesting just keep your TC a TC and use the technology out there for them.  It is currently in a high state of evolution and development, just use what is out there, and you will be much happier IMHO.

Regards,

-Tutt

[ocezam]

I thought the 2 cam design with silent chains was used to remove noise from the motor. Less motor noise meant the exhaust note could be louder.....

Single lobe?.  Doubt it. Unless it's from a lawn mower.

[les]

The best thing they did was go to a single cam. The chain drive makes it easier to keep it quiet. There's a lot of improvements there that you're not seeing that will show up down the road as they start coming apart for upgrades.
If I was to improve on the 45* V Twin I would have done it the same way. There's a lot of potential in that motor with a lot less stress on it than those damn twinkies.

I agree.


Sent from my iPhone using Tapatalk

[Templer]

A 4 valve hemi conversion was available, but it never really delivered the performance advantage it promised at a practical price point.  http://thekneeslider.com/4-valve-hemi-heads-for-harley-big-twin-engines/ There just wasn't enough interest and development time for it.  Two valve technology meanwhile really took off afterwards and 4 valve head conversion development stalled out. 

Its why I keep suggesting just keep your TC a TC and use the technology out there for them.  It is currently in a high state of evolution and development, just use what is out there, and you will be much happier IMHO.

Regards,

-Tutt

The site linked states for EVO and "early TC" motors?  Does it already exist M-8 conversion??

[mp]

The only reason to use a chain is ease and speed of assembly.  Evolution gear drive cams are dead silent.
As for hemi-heads, they do make power but they also make a lot of heat due to their inefficient combustion.

[moscooter]

 
I'm seeing chat about the chain drive, the single cam, the four valves per cylinder and (why) surrounding all of those things in the new motor.  What I'm not seeing much mention of is...................(2) spark plugs per cylinder.  Was and/or is that really necessary and I'm hearing that access to one set on each cylinder bank requiring the gas tank removal or some such.

[Jako1]

New case with balancer
The TC will be no more IMO once the MOCO redesigns the Dyna Chassis
The VRod is no  more after this year along with the FLD

[actonern]

The most recent American Iron magazine has a review of the new M8 bikes, and the author, Steve Lita, states...

"With the inception of the Twin Cam, the valvetrain required the use of two cams because of the necessary pushrod angle with the old two-valve heads.  But now, with the transition to 4 valves, the single cam comes back into play."

Does this sentence make any sense?

[PoorUB]

Yes.

[Piston Broke]

I'll bet on 'no'.

It's not the number of valves involved that matters, it's the relative position of the rocker arm shaft.

It's nonsensical on both counts, i.e. the why for the TC and the M8.

It's like saying, "The Sportster needs four cams because of the position of the pushrod tubes".