x30 jUNIOR (26/29/31 header)

HIGH SPEED NEEDLE : 1 1/2 TURNS OUT (1 HOUR 30 MIN) (see this note regarding X30 needles)
LOW SPEED NEEDLE : 1 TURN OUT (1 HOUR)
EXHAUST TEMP (EGT): High reading: 1,100 F TO 1,175 F (593 C TO 635 C) Low reading: 800 F to 850 F (427 C TO 454 C)

CARB POP-OFF PRESSURE: 9 - 10 PSI,  GAUGE SHOULD HOLD BETWEEN 6 - 8 PSI

-standard inlet spring: 37 gram (part#: 24B-299) click to purchase

-alternate spring (slightly higher pop-off): 42 gram (part#: 24C-298) click to purchase

FUEL / OIL RATIO: 16:1 (8 OZ / GALLON) OR (63 ML / L)

EXHAUST LENGTH: CLICK HERE FOR MEASUREMENT INSTRUCTIONS AND NOTES

17” minimum per SKUSA starting 01/01/2019

18.25 in (463 MM) for 26 HEADER

17.75 IN (451 MM) FOR 29 HEADER

17.5 IN (444.5 MM) FOR 31 HEADER

OPTIMAL WATER TEMP: 125 F / 51.7 C
SPARK PLUG:

NGK BPR9EIX (IF PERMITTED)
NGK R6252K-105 (FOR USE AT SKUSA, WKA, USPKS)

SPARK PLUG GAP: 0.03 IN OR .762 MM

GEARING/RPM: Gear to achieve a top rpm of:

26 HEADER: 15,000**
29 HEADER: 15,500
31 HEADER: 15,800

**The rpm range for the 26 header is much more varied than the 29mm or 31mm. Some tracks you will find you don’t even need to get to 14,000 rpm to be in the optimal power window. Basically, the more you restrict an engine, the more difficult it is to predict how it will respond to gearing and tuning. Your best bet with any gearing choice (regardless of header size) is to tune for the best bottom end performance and let the top end sort itself out. Ideally, you want the low rpm to be above 7,000 on the slowest part of the track.