Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[moscooter]

 
http://www.sscycle.com/admin/uploads/instructions/51-1037.pdf

If you want to know more about how balancing is done,  take a look at the above info from S&S.

Meantime,  I'm trying to decide if you're just trying to jerk my chain.........Surely you don't believe that the "A" motor which comes in the Tour models and the Dyna models has a crank assembly that is "unbalanced" and that HD decided......hummm......maybe we should come out with a motor that has a balanced crank assembly and won't shake,  We'll call it the "B" twincam motor......that will attract some new buyers

The softail family that uses the "B" motor are and always have been hard mounted to the frame.  So instead of being rubber mounted as the Tour/Dyna models are.......which allows the motor to shake in the frame with less effect on the frame and rider.....they kept the hard mounted concept (for dubious "styling" reasons) and added the counter-balancers to the engine to counteract the inherent shaking of the motor.  To my understanding,  it is the bearings that support the (additional) counter-balancer mechanism that go bad at high revs........NOT THE CRANK BEARINGS THEMSELVES!!!!!!!

I hope you now have a better understanding of how and why the B motor cannot be reved as high as the A motor and survive........if not,  I'm passing the baton to someone else to try and help ya.

[djkak]

http://www.sscycle.com/admin/uploads/instructions/51-1037.pdf

If you want to know more about how balancing is done,  take a look at the above info from S&S......,  I'm passing the baton to someone else to try and help ya.

My understanding of the RPM limitation for the “B” engine is that beyond 6,200 RPM you risk exceeding the capacity of the hydraulic tension mechanism for the counter weight drive chain. When this chain loosens up the counter balance weights can shift out of phase, or worse. A mechanical malfunction resulting from a loose drive chain means that the crankcase must be split to repair.

[mrmagloo]

No, I hear what you're saying, but I guess I'm just trying to understand the logic that a supposedly 'more' balanced motor has a lower RPM capability as a result of using a counter-balancer, which should make it easier in the bearings andd such. If it's a function of the counter-balancer itself, I guess that makes sense? Just asking.  I've actually always wondered why they don't use the B motor in the Touring bikes with harder durameter urethane mounts.

[grc]

No, I hear what you're saying, but I guess I'm just trying to understand the logic that a supposedly 'more' balanced motor has a lower RPM capability as a result of using a counter-balancer, which should make it easier in the bearings andd such. If it's a function of the counter-balancer itself, I guess that makes sense? Just asking.  I've actually always wondered why they don't use the B motor in the Touring bikes with harder durameter urethane mounts.

I would love to see a "B" motor in a rubber mount frame, but I sincerely doubt we will ever see the MoCo spend the bucks to do it.  The "B" motor costs more to produce, and they can get acceptable vibration control in the rubber mount bikes without that expense.  Knowing how the management of H-D squeezes pennies until Abe's eyes bug out, it "ain't gonna happen".

My understanding of the rev limits for the "B" motors is the same as what was posted by djkak earlier.  The drive mechanism chosen by H-D for the counterbalancers is the limiting factor.  If one were to use better components or a better design the balancers wouldn't by themselves limit anything.  There are counterbalanced engines from other manufacturer's that run much higher rpm's than the Harley.  BTW, I owned a 500 Yamaha back in the early 70's that had counterbalancers and that bike pulled much higher rpms than the current Harley even back in the dark ages.

Jerry

[kev]

Simple fact that on B engines the counter balancer is something extra for the engine to turn will sap power/rpm,  in a similar way to adding
something like a power steering pump or air con to a car engine.... just my opinion for what its worth.    I had experience of both
in 88 form and found my Deuce with the B engine smooth as silk, but my wifes 88 Dyna a little quicker to respond but a bit more harsh.

Kev