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sc400ex_rider
06-04-2007, 06:08 PM
stock 450r carb has a 118 main jet while the stock 400ex has a 148 main jet. how could this be? the r carb is bigger letting in more air so it needs more fuel right? or is this just for emmissions or to detune the r a bit?
Dill
06-04-2007, 06:23 PM
the 450R probably has a stronger signal (vacuum) which will draw more fuel through a smaller main jet. Every engine is different in this matter.

That being said, it probably is somewhat of an emissions issue as you mentioned as well.
JOEX
06-04-2007, 07:50 PM
These may or may not be helpful...

http://www.exriders.com/vbb/showthread.php?s=&threadid=143853

http://www.exriders.com/vbb/showthread.php?s=&threadid=231507