1985 250sx throttle/carb problems

[85_250_SX]

First off hello i am new to the forum, this is my third trike, a 1985 250SX it idles excellent nice and quiet but soon as i apply throttle the engine loads up, i changed the NGK plug that came with the trike, i started the bike let it warm up it still loaded up but the odd thing is that reverse gear does not load up i can wind the engine out in reverse soon as i catch a forward moving gear it loads up i feather the throttle until i can get it up to speed and it runs fine but soon as i pin the throttle it begins to cough and load up until i back it off to about 75%. im not sure if it matters but first gear is trashed it kicks and jumps so i use 2-5 it starts fine, idles fine just have to feather the throttle, possibly old gas it came with 3/4 tank i topped it off with fresh 89 and put some SeaFoam that helped my dirt bike out a 2005 CR450F that sat for a year im open to any experienced mech's suggestions possibly just yank the carb and do a thorough cleaning?

[mohadib]

What do you mean by load up?

[Thorpe]

if its like my BR carb (which it is) the float, and needle where way out of spec... Cant get a new float anymore, but you can have a beer and shim it with the aluminum can... (if its out of spec, I will explain later)

[85_250_SX]

By loading up i mean coughing and sputtering acting like the engine is getting to much gas and choking out when i apply throttle it slows down then finally with feathering the throttle will get up to speed but never will allow 100% throttle to wind up the rpm's it has me puzzled as Ive never had to work on my previous trikes a Honda 200s (stolen) Yamaha 200 i sold, both ran great i miss my 200s topped out on asphalt at 60mph but i did confirm a purchase of 2 200x's one running one needs a head for a cool $500, the one that needs the head the owner tells me the previous owner shaved it too much and it made a tapping sound he shut off the trike and never ran it again