Rivera Primo Shovel & Iron Xl Evo Big Twin & Twin Cam Models - Manual (Page 7)

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Stock Applications: Shovelhead, Sportsters, Evolution Models
Supplied with kit as standard: .100 Mainjet - Red Spring 4-1/2 oz. - BBT needle.
Stock 900cc Sportster: use BBD needle, 4-1/2 oz.spring, .100 mainjet.
Modified Shovelhead and Evolution engines w/headwork, cams, etc: use BBT needle, .100 Mainjet , silver
spring 8oz., (BBX alternative needle).
For STROKED engines the mainjet should be changed to Rivera Primo Part #RE-1453A(.1015) or RE-1453B(.1024)
All needles for both Eliminator I &II are supplied with collar attached to shank for use as spring-loaded needles.
Needles: LEANEST to RICHEST- BBD, BBT, BBX, BCJ, BBZ, BBT standard.
Spare jetting includes a richer needle (BBX) and a leaner needle (BBD) or substitutes.
The mainjet is adjusted for starting purposes when shipped. If it ever becomes necessary during tuning
procedures to turn the mainjet adjustment screw more than two full turns either way, a different tapered needle
should be installed and the mainjet set to the neutral position for further tuning.
The tapered needle is fixed inside the piston. NEVER loosen the set-screw and raise or lower the needle.
The needle guide which holds the needle should be flush with the bottom of the piston.
Standard installed needle and seats are designed for gravity flow. For racing purposes or large stroker
engines we suggest using our fuel bowl spacer, Part No. RE-680-S. This part will double the float bowl capacity.
Our PRIMER PUMP (Pat.No.4,228,110) is a pressure system.The pump is a press fit inside the body and
SHOULD NOT BE REMOVED. The brass nut can be removed to clean the inside or change the viton cup.
If FUEL should drip or flow from the tickler pump, shut off the fuel immediately. The bottom cover will
have to be removed to visually check the needle and seat or the float level. It is possible dirt will cause the needle
to stick inside the seat. It can be removed for cleaning or lightly blown out with an air hose.
The float level should be checked and adjusted as shown in SETTING THE FLOAT LEVEL illustration.
Piston springs are a tuning asset. Stock carburetors have the weakest spring installed (4-1/2 oz.).
By changing springs we can accommodate a slight mixture change. A stronger spring will richen the mixture over
the entire RPM range.
NEVER use any oil inside the dampner. Oil will slow the rise of the piston causing an overly rich mixture.
Every 30 days unscrew the dome cap and lightly spray around the piston shaft with WD-40. The piston must float
freely at all times to accomplish the constant velocity principle of allowing the engine to determine its position.
Rivera Primo manufactures stroker size manifolds for popular stroker kits. If you require a stroker
manifold please ask when placing carburetor orders.
SU NEEDLE GUIDE
NOTE: The numbers under each needle is the profile dimension of that needle.
Dimensions are taken every 1/8 ” from the top shoulder.
LEANER RICHER
BBD BBT BBX BCJ BCJ
.099 .099 .099 .0995 .098
.095 .096 .095 .0967 .0954
.092 .0932 .0932 .0939 .0924
.090 .0903 .0905 .0909 .0892
.088 .0877 .0875 .0881 .0862
.0862 .0850 .0852 .0848 .0819
.0844 .0827 .0829 .0781 .0780
.0825 .0807 .0806 .0740 .0751
.0818 .0792 .0782 .0703 .0713
.0808 .0778 .0755 .0671 .0673
.0798 .0765 .0730 .0650 .0653
.0788 .0753 .0702 .0630 .0629
.0778 .0740 .0675 .0610 .0605
.0768 .0725 .0650 .0590 .0580
.0758 .0713 .0624 .0570 .0560
.0748 .0700 .0598 .0560 .0540
(Standard)
SPECIFICATIONS & SPECIAL NOTES
SU Instructions 1108-0001_SU Instructions 1108-0001.qxd 10/4/12 10:13 AM Page 7