carb jet question

[njkx]

Can the main and/or pilot jet from an 05 yz250f be used on an 08 yz450f? I know it is a different carb but the jets look to be the same to the naked eye. thanks.

 

[sharky243]

They should fit if they are both Keihin carbs, but I don't recomend it because they are calibrated differently. Try this jetting, #160 main jet and a #50 pilot jet. Turn the mixture screw out 2 1\2 turns to start, then fine tune after the engine is at normal operating temperature. This jetting works great in my 03 yz450f. Keep in mind that air temperature, humidity levels, and altidude will all affect the jetting. So adjust your jetting as required for your riding conditions.

 

[Matt90GT]

Both are the same FCR carbs. Different size but they all use the same jets, needles and diagaphrams in them (but different sizes).

 

[njkx]

thanks. got it. really difficult to get at....the carb wont turn to the side like the old 05.

 

[Matt90GT]

nope. You have to remove the subframe, rear shock and upper motor mounts, then pull the carb straight up the back of the head to get access to it.