Fmf jetting

Blaster-420

New Member
Dec 11, 2017
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So I just bought a fmf fatty gold series and I'll just trying to figure out the jetting it's bone stock besides the pipe and silencer I live in upstate NY right near Canada so right now it's cold out and right around 200ft above sea level I've seen people on here say 280 main but on fmf they say 260 main 32.5 pilot needle position 3rd and air screw at 1.5 and they say they created those specs at 32:1 ratio 0-1500 ft elevation and 50/50 mix of race fuel and super unleaded and remove air box lid and that's at 70 degrees outside temp but i won't be using race fuel just super unleaded any help would be great please and thank you
 
I wouldn't worry so much about the fuel , if concerned just run premium.

Depending on how cold of weather you are willing to ride in , I would say 300 and plug chop , keeping track of the temp so you can adjust for changes in temps.

Be aware you can cold seize if real cold and you're running WFO on the ice , etc. A piece of cardboard in front of the engine will protect it from wind chill factor.

FYI , my son cold seized WFO on the ice in 0/-10 temps
 
Although FMF says the air screw at 1 1/2 turns out , it is just a starting point.

You do need to set the idle speed and provide good transition onto the needle..

Idle adjusting.
Set float level, make sure that all jets are clean and fuel flows freely from the float bowl drain
when the screw is cracked open.
Start with air screw 1.5 turns out.
Set idle screw so that it has some sort of idle. With TORS it is the big screw under seat on top of
unit. With no TORS is is the brass screw midway down carb body.
Warm up motor and then set idle screw for a faster idle, 2000rpm+
Adjust air screw either way to get the fastest idle.
Adjust air screw a little at a time leaving 10 secs or until the motor responds.
Re adjust idle screw for desired idle .
if the air screw ends up being more than 2 1/2 turns out the pi;]lot is too big.
if the air screw is less than 1/2 a turn out the pilot is too small