i just bought a 96 magnum 425 and the guy i bought it from had it sitting up for a few years so when i test drove it this prob didn't bother me so much i figured it just needed a tuneup anyway it starts right up and idles just fine it even takes off real well but when i get up to 25-30 mph or 3/4 throttle it starts sputtering and cutting out so after two dayz of calling shops and trying almost everything i know im still stuck i've changed the spark plug, oil , oil filter , air filter , cleaned the carb out, and the put fresh gas in the tank which did help a little but not much the only thing i haven't tried is taking the muffler off and seein if its clogged but ima do that later on today i really dont think that is the prob so thats why im here i need help guys any feedback or suggestions would be great

 

Two more things to check would be the valve clearance and cam wear along with taking the rear clutch apart and checking the ramp buttons

 

CAM!!! I agree my buddy F here, exhaust lobe. Good luck keep us up to date. Doc

 

having the same problem, but shops keep telling me its going to be my main jet in the carb and not the small jet, i can turn the key on and just hit the start button and it cranks are 1 pull with the pull rope and it cranks, but when i get down on it are put any stress on it boggs down, are u sure u cleaned the main jet out real good

 

yes im positive

 

if u cleaned the carb i guess u cleaned the choke also, just taked to another guy and he said it sounds like the choke is sticking in the carb. here is what mine is doing, cranks very easy and then after it warms up just a little, i get down on it and it cuts out and just boggs down, then it start smelling rich. cant believe i didnt think about the choke. but i do have the same bike with a very similar problem.

 

well mine isn't smelling like it is running rich and it boggs and spits when it is cold or hot

 

I had the same problem with my '96 Magnum. The jet needle and the needle jet were worn. You could actually see the difference in size between the old one and the new one. They had a vibration issue that caused them to wear. Does yours have a brace from the rear of the carb to the frame? They came up with the brace to fix the vibration problem. I'd give that a try after you check your cam for wear. The difference on mine was night and day.

 

yea mine does have the brace . OK now for an update i was reading other topics on here and i saw where someone was having the same prob with his polaris and he said when he removed breather hose from the back of the carb his quad ran perfect well i tried the same thing and got the same results my new toy came to life and started flying i must admit i am very impressed with the get up and go this polaris has anyway........ back to the prob i just installed a brand new air fliter and there is nothing blocking ither airway in the breather box so now its back to square 1 somebody HELP ME ! ! !

 

hey there, i have read all of your posts, and i am having exactly the same problem, have you found a solution to it yet? I purchased mine thinking the exact same thing and when i took the breather off it came to life, just the same, but i cannot put it back on without it bogging back down, id love to hear a solution if you have found one!!!