Air/Fuel Screw ( Happy Day )

[LdiBiTi300EX]

Hi ExRiDarZ!

I got a 300EX and i checked my spark plug and im running lean but I neverhad problems because of that. My Air/Fuel Screw was turned to 2 turns .Do i Need to Turn it out or turn it in ? The 300EX is ALL stock

In : Richer?
Out : More lean?

Thx Guys!

[mascman]

On my 450r, in is lean...out is richer.

[cals400ex]

IN leans the bike

OUT richens the bike


by the way, this is for our carbs. many of the other carbs don't have fuel skrews like ours and have air skrews. these you do the opposite on.

[haywire4130]

spark plug reading isn't very accurate any more. the blends of fuels nowadays almost always make the plug look lean. this is more or less to get a ballpark, not to fine tune the machine. if it runs good and doesn't miss or backfire, go with it. also, if you want to experiment with the pilot screw just as a learning thing, try turning so it's at a half turn out. with the bike running. blip the throttle once and listen for it to come back to idle. it will hang up and slowly fall back to idle (too lean). now put it at 3.5 turns out and rev it. it will dip below idle and then come back up. this is too rich. you want to set it so it revs quick and comes right back to idle. this is more accurate then checking your plug, plus it will give you some experience hearing how rich and lean effect the motor (at least at idle). the pilot circuit only affects idle and low speed operation. this is how i tune street bike carbs. good luck