REF: Engine Mechanicals

Top End

Heads

Alternative to Stock Heads 1992 - 2006 Models

Valves

Pistons

CP pistons is who makes the pistons for both NRHS and Hammer. 1)
But they are not the same pistons as they each have them made to their own specs.
CP is a custom piston manufacturer like Ross and others. 2)
They have a standard line but they also make pistons to their customers' specs.

CP piston from Hammerperf.com. Two wrist pin oilers
per side, plus a groove to spread it around. 3)

Wrist Pins

CP / Carrillo Wrist Pin (3H-1C)
Supplied with the 1250 kit from NRHS Performance. 4)

Wrist Pin Retainers

These keep the wrist pin from coming out of the piston and scraping the cylinder walls.

Pins coming out of pistons is an enormously rare event. 5)
However, if the retainers are not installed properly, they will come out.
CP, in previous years, had some issues with the manufacturing of the pistons.
Wiseco had an issue many years ago also. They weren't putting the appropriate chamfer on the wrist pins for the circlips.
Bottom line, if the clip is installed right, and none of the parts are defective, the clip is a stone reliable solution.

Below is a cylinder that had a wrist pin retainer come loose.
6)

Wrist Pin Lock Rings

These circlips are used with wrist pins that have a chamfer on the ends.
The theory is that the chamfered edge on the wrist pin should push the round circlip into its groove when pushing on it. 7)

Wrist Pin Buttons

Teflon or nylon buttons can be used instead of circlip retainers.
However, the pistons have to be designed for their use.

Nylon buttons take the place of the retainer rings. 8)They can be ordered along with the pistons. 9)

Rings

Pushrods

Alternative to Stock Pushrods

Screaming Eagle Pushrods for Sportsters

  • SE “Perfect Fit Pushrods” for Stock Heads 1991-2006 - (18421-06) stock SE length.
  • SE “Perfect Fit Pushrods” (18424-06) for Single Plug SE Pro Heads (16677-05) 1992-2006
    (published as - 0.050“ under stock). However, it appears they may be 0.050” under their stock “Perfect Pushrod” inventory since they are definitely shorter than 50 thou that for 'factory stock pushrods'.

The pic below is a comparison between the suggested 'Perfect Fit Pushrods' and standard rigid Evo 1200 pushrods. The SE pushrods are tapered with a beefier bottom end at 0.434“ OD tapering to the standard 0.375” OD at the top. Even though the heads have been shaved 0.050“, the intake pushrod was shortened by 0.071” and the exhaust one shortened by 0.065“. Length measurements were taken with a 12” Starrett vernier caliper.

SE "Perfect Fit Pushrods" for Dual Plug SE Pro Heads - (16457-96B or 16458-96B) 1992-2003

  • Kit # 18421-06 (stock SE length)

Pushrod Tubes

Hammer Performance Billet Base Kit

Fits 1991-2003 Sportster and 1991-2002 Buell (except Blast).
The stock lower pushrod tube retainer on a 1991-2003 Sportster is a cheapo piece of pot metal that bends and distorts, causing leaks. 10)

These pushrod tube bases are stronger than the stock parts replace the cheap stock pushrod bases using your stock pushrod tubes.
They are CNC machined by Hammer Performance out of T6061 billet aluminum.
Each kit comes with two bases, the upper o-rings, the lower seals, and four stainless steel screws.

11) 12)

Aftermarket Rocker Arms

Roller rockers can't do anything but help the valve train. 13)
They can help extend the life of your valve guides and seals.
Take side to side pressure that a normal rocker tip can put on the push rod away.
They may also make your top end more quiet also.

If you look at it the end if the stock rocker arm, it's like the tip of your finger. 14)
As the rocker is pushed down on your valve since it has a curve like your finger tip.
It is also putting some sideways pressure on the valve.
It really gets exasperated when you have high lift cams which put more pressure on the whole valve train.
(especiallly if you use heavy duty springs)
Most use the beehive springs now so that's not as much of an issue.

S&S Roller Rocker Arms 15)


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