I have an SPE 43 that runs very well from just a little under half to full throttle, from idle to just under half it runs pretty rough and does not sound very good. I have adjusted the low end needle a small bit about an 1/8 turn and it seems to help some.
How do you know how far you can safely go on adjustments?
The motor has about 2 gallons thru it, it just started running poorly today.

Thanks

If you get the low speed needle too far in, the engine will quit when you try to give it the throttle.

Just open up the low speed needle enough to where the engine will accelerate when you advance the throttle.

If you can adjust the low speed mixture while running...turn the screw leaner(clockwise) until the engine starts to slow down, then turn the needle counter clockwiseuntil it speeds up and keep turning until engine begins to slow down. Notice the position of each point and set at a point 1/2 way between. That should be close. If when you open the throttle the engine has a big hesitation...turn the needle out to richen it again until the engine revs up without hesitation. Do this after the engine is warmed up. Capt,n

I think the carb idle circuit controls the fuel flow through much of the lower RPMs. Since the problem has just recently started, I would check the idle paths for dirt, including the idle needle jet. Look at the flow diagram for the particular carb you have and you can see the fuel flow at different butterfly openings.

Regards,
Richard

I did a little last minute drilling on the motor box today so I could adjust the needles with the motor running, I ran the motor for a couple of minutes at various throttle settings to let it warm up and then started leaning out the low end. After i was happy with the way it ran and sounded I had turned the needle about half a turn.
My idle is right at 1950 and my top end is only 6450 but it hauls my 11 lb yak around very well.. I am turning a 20x10 xoar prop, the top end seems low just looking at the numbers but performs very well..

Thanks for the tips guys..

Hmmm....if it ran ok, and it just started running poorly, why would you go after the needles?