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Discussion Starter · #1 ·
As a first time HD owner, I have to satify my curiousity.

Why does the HD engine idle so rough?

Of course it runs nicely once you accelerate, but why not at idle?

Can someone explain this?
 

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Anthony8858 said:
As a first time HD owner, I have to satify my curiousity.

Why does the HD engine idle so rough?

Of course it runs nicely once you accelerate, but why not at idle?

Can someone explain this?
The engines are not balanced so when the flywheel spins slower it shakes the engine more. The faster you spin it, the smoother it becomes, to a point.

It also has to do with the 45 degree engine using a common crank pin. In this design the flywheel rotates 405 degrees and fires a plug, then it rotates 315 degrees and fires a plug, then 405 degrees again, then 315 and so on. At a low RPM, the difference in rotation distance is more noticable, hense the sound that a Harley makes. After the flywheel turns 405 degrees it is technically turning slower when the plug fires as opposed to the 315 degrees and then firing the plug. This means every other plug firing is to a slower flywheel and this contributes to the vibration of the engine.

Add all those factors add up and you get the "rough" idle I think you are talking about.

The TC88-B engines have counter balancers in them that spin offset weights to counter the flywheel weight. When the flywheels are "throwing" weight forward, the counter balancers are throwing weight backwards nullifying the vibrations. In basic terms.
 

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You can keep the bike parked in the garage as a show peice, this way the rough idle wont be a factor
 

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03FLHRI,84XLH,52ArielVHA
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I once read a statement by British riders talking to other British riders that when you first ride a Harley you are in for "culture shock" I suspect they meant that if you've ridden any other bike you were going to find a Harley very different. The low speed vibration is the first experience of this "culture shock." Enjoy it.
 

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Discussion Starter · #9 ·
Archon said:
I once read a statement by British riders talking to other British riders that when you first ride a Harley you are in for "culture shock" I suspect they meant that if you've ridden any other bike you were going to find a Harley very different. The low speed vibration is the first experience of this "culture shock." Enjoy it.
I'm lovin' it!

Iwas just being a little curious. {salute(
 

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springer- said:
The engines are not balanced so when the flywheel spins slower it shakes the engine more. The faster you spin it, the smoother it becomes, to a point.

It also has to do with the 45 degree engine using a common crank pin. In this design the flywheel rotates 405 degrees and fires a plug, then it rotates 315 degrees and fires a plug, then 405 degrees again, then 315 and so on. At a low RPM, the difference in rotation distance is more noticable, hense the sound that a Harley makes. After the flywheel turns 405 degrees it is technically turning slower when the plug fires as opposed to the 315 degrees and then firing the plug. This means every other plug firing is to a slower flywheel and this contributes to the vibration of the engine.

Add all those factors add up and you get the "rough" idle I think you are talking about.

The TC88-B engines have counter balancers in them that spin offset weights to counter the flywheel weight. When the flywheels are "throwing" weight forward, the counter balancers are throwing weight backwards nullifying the vibrations. In basic terms.
Do you know why it was designed that way? I once heard an old fella talk about it and he said they wanted a unique sound, but figured it was designed that way for cost. At any rate, I wouldn't want to give it up, it's one of the things that makes it a Harley. Yesterday a Honda rider was telling me about riding a new Ultra last summer and the transmisson clunked when he shifted - "Yes", I said ,"mine does too" it's one of the things that makes it a Harley.

Some people will argue that veggi-burgers are better for you, and the same as 100% beef - but some still prefer the taste of real American beef. It's not unlike the Harley, other bikes may be better made and do things better, but you find yourself saying "Where's the beef?"
 

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The Alter Ego
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You ever notice that everything is compared to a Harley?
1. "Looks just like a Harley"
2. "Sounds almost like a Harley"
3. "Has more horse power than a Harley"

Noticing a pattern? Forget the metrics. Just purchase the standard.~!Awesome!
 

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Rock_Steady said:
You ever notice that everything is compared to a Harley?
1. "Looks just like a Harley"
2. "Sounds almost like a Harley"
3. "Has more horse power than a Harley"

Noticing a pattern? Forget the metrics. Just purchase the standard.~!Awesome!
not really...
 
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