Jet Keihin Pilot #42 (FCR-MX) (4/Pkt)

The Keihin Pilot Jet #42 is a replacement pilot (slow) jet designed for use in Keihin FCR-MX flat-slide carburettors. Pilot jets govern fuel delivery at idle and low throttle openings, making correct sizing essential for clean off-idle response and reliable starting.

Sold as a pack of four, this kit suits riders who are dialling in their carburettor jetting or want to keep spares on hand for track days and trail riding. As a genuine Keihin component, it meets the same manufacturing tolerances as the original equipment jet.

• Genuine Keihin pilot jet sized #42
• Designed for Keihin FCR-MX flat-slide carburettors
• Controls fuel delivery at idle and low throttle positions
• Pack of 4 jets — suitable for jetting experiments or stock replacement
• OEM-equivalent manufacturing tolerances

• 4 x Keihin Pilot Jet #42 (FCR-MX)

When changing pilot jets, drain the float bowl fully and allow fuel vapour to dissipate before working near an ignition source.
Never use wire, drill bits or abrasives to clean jet orifices — these alter the calibrated size and will affect mixture.
Clean jets by soaking in carburettor cleaner and clearing passages with compressed air only.
Inspect each jet for corrosion, burring or thread damage before installation and discard any that show wear.
Apply only light hand-pressure when seating jets; over-tightening will damage the soft brass thread and the carburettor body.
When jetting, change one variable at a time and test-ride at the relevant throttle position before moving to a different jet size.
Store unused jets in a sealed, labelled container to prevent contamination and corrosion.
Consult your motorcycle's jetting chart or the FCR-MX needle/jet selection guide to confirm that #42 is the appropriate size for your altitude, temperature and engine modifications.