Greg,

I also believe the one carb you have is suspect. This weekend I fixed my SK-90 by using my TH-75 carb. My SK tuned up perfectly with the TH-75 carb.

Like David's carb, the design of the TH-75 carb I have is not like the one shown in the manual that comes with the engine. How to detect a bad one, that is still a mystery, I guess. In my carb, you never see the LSN because it is inside a tube sleeve that runs all the way across the carb throat. If you see it from the side of the venturi that goes into the crankcase (carb bottom), you see a square hole in the middle of such tube. There, you can see the LSN moving as you come close to WOT.

My problem now is I need a new carb, either for the SK or for the TH engine. David (rainedave) pointed me to the Perry carb. I always have the choice of buying another from TH when parts are available because I am not using the TH-75 engine right now. So, what's the cost of the carb you bought from Just Engines?

Pedro