i have tried so many different adjustments on the carb and nothing seems to work. i have NOT tried a carb rebuild kit yet. if i can find one for an 87, do you think this would solve my problem. it cuts out at half throttle and if i dont let off, it will die.

 

i see that you bought the bike as a project, did this problem exist when you bought it or did it just start to happen? what did you adjust with the carb? you have stock exhaust, do you have any other mods? how is your air filter? what position is the needle at? half throttle is needle in the carb, set it to the middle clip position. tell a little more about the quad then we can better determine what the problem could be.

 

The machine is all stock (as far as i know) i'm sure theres no internal mods that i dont know about because it was basically just a rider quad. to be perfectly honest, idont remember if it had that spudder when i first got it running mostly because i was afraid to go past half throttle. i know its sad, but its a big jump from a polaris 90. which screw are you talking about? the internal one? i fooled around with the one in the front of the carb near the intake manifold (turning it in and out) and it didnt really do much. what is the name of that internal screw and what should it be set at. Also, i noticed that a carb rebuild kit will only fit an 87. not any years after that. what was different for that carb then other year? was it like, a failed design that they changed?

 

set the screw by the intake manifold to 2.5 turns out using a stubby flathead or a flathead bit. the internal screw you are talking about, is this a brass flathead screw that hangs upside down in the bowl on the bottom of the carb? if so thats your main jet and it should be tight. if its not tight that could be the problem. let me know how you make out.

 

thanks for the 2.5 tip, i'll try that tommorow. suprisingly, i know what jets are and yes, there tight. its another screw that my dad adjusted internally and i cant remember off the top of my head what it is or what it looks like (other then a screw)

 

one more thing to check, when you have the quad at idle, spray some carb cleaner around the outside of intake manifold and the intake boot. if you hear the rpm's increase, you have an air leak. just trying to eliminate as many problems as i can think of. since the jets are tight, i assume you gave it a good cleaning inside also? let us know how it goes.

 

Thats a good idea, the carb cleaner idea. its probubly the original boot and it could maybe have a crack or tear. and yes, i've done complete cleanings NUMEROUS times on it, theres no blockage anywhere. i did notice that the fuel pump plunger doesnt move to its full potential at half throttle, infact it hardly moves more then maybe an eight of an inch. i was thinking maybe this was the problem, but i dont know how far that plunger has to go down to work its magic. what i mean by this is when the thing that pushes on it is all the way down on the plunger it doesnt push it very far. not to its full potential.

 

are you talking about the white plastic piece under the throttle cable cover pushing on something? thats the accelerator pump, it only serves the purpose of giving some extra fuel when you stab the throttle, its not supposed to move that far. on that subject, though, make sure you have the spring on the accelerator pump (in the bowl). i swapped the stock spring with a spring from a click pen, its alot more heavy duty than the stocker.
have you checked your cylinder compresssion? if you dont have a compression gauge, take the spark plug out of the hole, and put your finger over the hole. now hit the start button, if you have good compression you wont be able to keep your finger on the hole.

 

I'd put my money on having a cracked intake manifold. Happened to me twice.

 

mine had a pen spring in it when i got it. wasnt strong enough to push the plunger back up so i replaced it with a good solid spring from the hardware store. i still havent had time to do that cracked intake test, but it would make sense to me for it to be the cause. what do i do if it is cracked? can i JB weld it?