Problems with OS 40 FX
 

I'am used to the cheaper OS LA 40 engines and took the plunge
and bought a OS 40 FX 109 $ I did not know there was such
a difference in quality and performance ! The problem I'am
having is when I throttle down from full to idle I'am getting
a faster idle it then takes another 7-8 seconds for the idle to settle down to its lowest RPM idle is this normal for the FX ?

Problems with OS 40 FX
 

brudford


Sounds more like you have some drag in the throttle ,maybe dragging on the exit maybe even against the crankcase ,,but check it for the whole length, check all the anchor points if it is nyrod or cable in a sleeve , and the exit to see if there is flex or movement at the exit of the outer sleeve

Highlander

What kind of control linkage are you useing ?

Highlander

Problems with OS 40 FX
 

My FX dosen't do that, but I don't know why yours does.

Sounds Normal
 

This sounds very much like my 40fx ran, especially during break-in, always rich. If you adjust the low-idle adjustment and lean it out a bit, you will find that it will respond much better at the low end, and have a much better transition from low to high and back again. This did wonders for my ability to feel like the engine responded to full throttle when I wanted it to, instead of a good 1/2 second hesitation.

Also remember to re-adjust the high end needle after. Note this all applies if you have a good 10 runs on the engine, as you should run it lean until then, but after that, it is a sweet engine.

oops
 

Duh, not lean when breaking it in, but rich.

Problems with OS 40 FX
 

Your low end needle probably needs some fine tuning.

A little is a lot!
 

When I adjust the low end idle screw on my 46FX I have found that it takes VERY LITTLE movement of the screw head to make a notable change in engine performance. I tell people to just "lean on the screw a bit", even a 1/8th turn seems to jump past the correct adjustment on mine. Good Luck