I have a 97 explorer 500 with a mukini bst carb. It sat for a while and wouldn"t start,I cleaned it and made sure all the passages were clear. When I put it on it starts and runs good until 1/4 throttle when it comes on the main jet it hoggs up and won't throttle up. Any ideas? Im pulling my hair out.

 

You may want to look at the top diaphrgm for a small crack or split. With the engine off and carb. still installed you can stick your finger in there and raise the slide and you should here or feel air coming out of that little port also.
Since you had it apart ,make sure the slide moves freely and needle is in the middle position, you could try raising the needle one clip also. my book only goes back to '98 , i checked and with the bst carb. the specs. were either position

 

Thanks for yhe ideas I will give them a try, thanks again 4getful2