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mummer12

Fuel Screw

6 posts in this topic

I bought a MSR HP fuel screw last year and lost the directions on adjusting it. I know that there are numbers on it but do I have to go in all the way and then back out 1 full rotation for one turn? numbers mean quarter turns? What is everyone running on 06 YZ 2/14 turns?? Thanks

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Warm the bike up FULLY

Turn the IDLE screw in, to make a faster than normal idle

Begin turning in the fuel screw until the engine begins sputtering (you're leaning it out)

Slowly unscrew the FUEL screw, until you hear maximum RPM. STOP turning it.

Try riding the bike, and experiment turning the fuel screw in or out in 1/4 turn increments until you get the best response.

A handy hint.....When you acheive maximum RPM, you also want to listen for hearing the crispest throttle response. IF it sounds kinda Dull, and flat sounding, than you are still too rich.

oh, I forgot, set the idle back to normal when riding.

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Assuming the elevation stays the same and the only big change is a drop in air temp. minor humidity change, would a 1/4 turn out in my fuel screw correct the sputtering on decel. or in? Never messed with my fuel screw yet. Just wondering where to start. Also, don't have a small enough screw driver. Is it a flat head or Phillips?

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on my 03 yz 450 the fuel screw is out 2 n 1/2 turns. stock pilot jet. on my 04 wr 450 its out 3 turns on stock fuel screw. I need to go up at least 1 size on pilot screw on the wr .

Jay

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Like flintlock28s response above. Just to add, I just received a Zip-Ty fuel screw from JD Jetting. Same concept as your MSR. JD recommends to seat it (screw it in all the way), then back out 1 1/2 turns. Then start it up and fine tune with 1/4 turns in one direction, blipping the throttle at each setting.

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