Slow Speed System - Honda GX160 Tech Manual

Air Jet
Jet must be stock unaltered. As of 4-1-10 any jet pin goes in and sticks will be a DQ.
1. Main nozzle bore 0.0732" maximum #47 (0.078") no go.
2. Main nozzle will be checked with a No/Go Gauge ( 0.424") If gauge goes over dump tube –
carb is illegal.. This is best measured using a 0.452" rod type gauge with a 0.424" flat area
to be used as a go gauge.
3. Air vent holes on the side of the main nozzle must not be plugged.
4. Main nozzle must not be fastened into the carburetor body by anything other than the main
jet. It must not be epoxied or positioned by any other means.

Slow speed system:

1. Pilot jet: 0.0135" maximum #79 (0.0145") no go.
2. Pilot air jet: 0.0478" maximum #55 (0.052") no go.
3. Pilot screw: no spec
4. Pilot seat diameter: 0.0365" maximum #61 (0.039") no go.
5. Tip of pilot screw: 0.020" minimum.
H. Float bowl vent : 0.118" maximum #31 (0.1200") no go.
I. Needle valve seat: 0.0685" maximum #50 (0.070") no go.
J. The butterfly screw, the butterfly, and the throttle shaft must not be removed from the carburetor.
Any evidence of tampering will be a disqualification and suspension.
K. Decimal equivalents of numbered size drills chart on page 20.
Main jet size: maximum #82 - 0.033 no/go.
Main air jet: 0.0587" maximum #53 (0.0595") no go - at back of hole.
Main jet access passage: 0.0942" maximum #41 (0.096") no go.
Main nozzle:
6