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Heavy connecting rods

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Post Thu Dec 24, 2009 12:57 pm

Posts: 141
Location: USA
In reviewing past post it appears that it is a common practice to use heavier connecting rods and larger crank pins when improving the performance of 45's,wr's, k-models and kr's following the factories practice.However,was there any past failure analysis wherein a number of failures were attributted to either the small rods and crank pins.It is my thought that that a heavier and more massive rotating mass may not necessarily end up with a more reliable motor .It may be that the use of new materials like carrillo connecting rods or a properly prepared rod that has been shot peened may perform as well as a heavier sportster rod in the low compression flatheads.The difference in inertia between the light 45 crank and rod and the k kodel assembly at high rpm may be significant.I am really not sure that bigger and heavier is always the ansewer in these low compression motors at high rpm.If you have any thoughts on this please share them. :D :D

Post Thu Dec 24, 2009 11:30 pm

Last edited by panic on Sun Nov 28, 2010 6:41 pm, edited 1 time in total.

Post Fri Dec 25, 2009 3:39 am

Posts: 591
Location: Crewe, Great Britain


Harley was almost alone in fitting heavier pins/rods/rollers on racers, compared to equivalent street models... Specially the so called -54R for KR, XLR... Shortened on XR but still on the heavy side.

Most other racers tended to have lighter pins/rods/rollers for racing for less inertia.

Not every tH-D uner was happy with these heavy duty H-D race rods, some ran std Sporty set ups.


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