Dirt Bike Jetting            Trails home page

Jetting for altitude
 
Recommendations only.  Manufacturing tolerances may
vary from one bike to another.
Temperature affects jetting.
Colder air is denser and will
make your engine run leaner.

 You must learn to recognize
that your bike is running rich
or lean or you could seize your
engine or foul your spark plug.
The last number to the right associated with the needle is the position
of the clip in the groove counting down from the top of the needle
Bike Setup Altitude Main jet Needle Pilot jet
2005 Yamaha WR450 PowerNow wing, FMF
PowerBomb pipe, FMF Q2 SA		 8,500 - 11,000 ft 165 JD Red-5 45
2005 Yamaha YZ250 intake blade, V-Force reed,
FMF Gnarly pipe, FMF Q SA		 3,350 - 3,550 ft 170 N3CJ-2 45
2005 Yamaha YZ250 V-Force reed,
FMF SST pipe, FMF Q SA		 8,500 - 12,000 ft 170 N3CJ-2 45
2005 Yamaha YZ250 intake blade, V-Force reed,
FMF Gnarly pipe, FMF Q SA		 9,000 - 13,000 ft 168 N3EK-2 45
1999 Honda CR250 stock 7,500 - 10,000 ft 178 stock-2 42
1998 KTM 200 stock 3,350 - 3,550 ft 165 N1EH-1 45
1998 KTM 200 stock 8,500 - 13,000 ft 155 NOZH-2 38
1996 Honda CR250 stock 3,350 - 3,550 ft 185 stock-3 stock
1996 Kaw KDX 200 stock 8,500 - 13,000 ft 148 R1174K-2 40