I've got a older used OS 46 sf that I'm trying to get running. Doesnt run too bad, but when I go to wide open throttle it falls on its face or sputters or both. I've moved the air needle so many times, I'm know even it if close now. So, could somebody tell me what the factory setting is for the 46 sf for the low end needle? It will give me a good starting point. Thanks ,JT

You either have a bad glow plug or your idle screw is in too far.

Good luck,

Jim

I tired another glow plug. I need to know where to set the idle screw. As in 2 turns out or 3 turns out etc. Then I'll go from there. Thanks ,JT

That engine should be a gem. When warmed up and at idle, simply pinch off the fuel line to the carb. If the engine speeds up quite a bit, then lean out the low speed needle some more. Keep doing this until it speeds up very little when you pinch it off. You will have to reset the top end needle each time too. It has a twin needle carb, not an air bleed carb I think, so turning the low speed needle "in" will lean out the low end. Other than that, check all gaskets including the o-ring on the carb mount and check for piston, ring, or cylinder wear.

OS SF owners now have an option if they need a new piston and liner..... The Leo ABC piston and liner is a drop in fit! See the article at Just Engines. They sell them also....:-)

Ernie ([email protected])

I have an OS 46SF that runs great now that I got it tuned properly. I don't know what the factory settings were but my low needle is set at just a hair less than 4 turns out from fully closed and my high needle is set at about 2 turns out from fully closed. This gives me 12000 rpm with an APC 11/6 and smooth transition from idle to full.

Hope this helps.

Thanks gvetter thats what i need to know. JT