[AT] Rationale for firing orders

[Thomas O. Mehrkam]

The Harley is actually a two cylinder radial engine. Like an airplane
engine with several pistons missing.

BetCleve321 at aol.com wrote:

> In a message dated 3/22/2004 4:37:37 PM Eastern Standard Time, chill8 at cox.net 
> writes:
> I think that nothing  nothing has helped the popularity of JD's about as
> much as it has Harley Davidson.  And that is a good bit.
> 
> Charlie
> Well, Harley Davidson engines are spaced quite differently than poppin' 
> Johnnys. JDs have a 180degree crank with the pistons rising and falling at 
> different times. One up , one down.
> HDs on the other hand have their pistons rising and falling together although 
> the two cylinders are splayed 52 degrees apart.  You do the math. Firing 
> sequence will be slightly uneven as a result rather than a smooth beat such as a 
> Triumph or BSA twinn. Balancing problems are hell, The JD layout has primary 
> balance worked out but firing impulses are uneven.
> They both sound good though.
> 
> Skip
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