I I have the YS .61 longstroke rear exhaust engine in my Tiporare, and there doesn't seem to be a low speed needle. It loads up pretty bad when idling, so I'm thinking it needs some sort of adjustment. Anyone know where the low end is?

Look on the bottom of the crankcase and you'll see a brass regulator screw just below the carb. This should initially be set so that the brass screw is even with the top of the housing it sits in. This screw applies pressure to a spring which adjusts the regulator which returns fuel to the tank. Adjust it in very tiny increments. Find the lowest rpm where the engine idles reliably (try for 30 seconds and then open it up - you don't want any hesitation). Then adjust the needle for proper mixture at high rpm. Then repeat. You will have to screw the brass screw in or out to get a lower idle without loading (2000 rpm or less - it will depend on the prop). Don't forget to readjust the high end after each regulator adjustment. And adjust the regulator screw in very tiny increments - 1/8 turn or less.

Jeff
Skylane N9214G
SPA 243

What Skylane says is right on. Just to clarify one minor point of possible confusion in his explanation, where he says "This should initially be set so that the brass screw is even with the top of the housing it sits in." Another way of saying this is that the screw should be flush with the lower engine case. I have a couple of these engines and when the screw is flush, the engine runs fine.

So there is no seperate needle for the low end, it's only regulator pressure that drives that? If I'm running rich (bogging after idling) I'm guessing the regulator needs to come out 1/8 turn?

Correct, the screw in the bottom of the engine case is treated similar to a low idle adjustment screw. And like most of those, IN is leaner and OUT is richer.