Hello, all! Long time luker first time posting.
To get right to it - I inherited my Grandfathers '95 Polaris Sportsman 400. It's my first ever 2 stroke and second carburetor engine. I'm a Diesel guy and I know next to nothing about the Carburetors. My other Carburetor engine is a '77 C20 that I'm restoring and havent had to mess with that carb at all so far. So this four wheeler is the only one I've ever had to tear apart and troubleshoot.
Here's the story on it; The polaris was my grandfathers until he passed in '04 and it went to my father who never used it, loaned it out to my dead-beat cousin to use as a snow plow until he ran it out of oil until it seized and pawned it 11 years ago. Finally I convinced my dad to give it to me to fix up and use for hunting. I got it home, tore it all apart, knocked the piston loose, didn't find any bad scars on the cylinder walls, cleaned it up with just a dingle-berry hone and cleaned the cylinder head and piston head up, put it back together and fired up on the second pull! That's when I realized the Carb needs some help. It wouldn't idle at all and would die at high RPM. So I took the carb apart, cleaned it up with come brake cleaner, put it back together, same issue. Took it apart a dozen more times doing the same thing until I found more than one jet, cleaned all that up until I could see light through it, put it back together again, and the idle was better, but only if the carb wasn't DUMPING fuel out of the pilot and it would actually start. So I got a rebuild kit for the carb and put it back together for the 100th time and now it fires up and idled better until it would run away after the slightest of throttle input and I had to choke it out with my hand and it would suck all the fuel out and I would have to drain the carb to get it to start again. Found out I put the throttle cable back together incorrectly, fixed that, put it back together, now it idled REALLY low but would still dump fuel out even when the engine is off. I tried playing around with the Float arm and the needle 'n seat and nothing I did changed it. So I figured "well it's running fine. I'll just turn the pep-**** off when it's off so I don't flood it and it's not leaking fuel everywhere." Put it all back together.
Time for the first drive!
Took it out after figuring out a binding issue with reverse and 4x4, Got it on my street and immediately noticed that the throttle isn't returning and have to physically push it back.
Okay, I can deal with that. it's a 24 year old bike and that spring is weak. Fine.
Now time to see how fast it can go!
Started pushing it further and further every pass I make. Now, sometimes, It will sputter and bog if I give it too much throttle too quick and have to back out for it to rev back up. Oddly, If It's in neutral, I can rev it to the moon no issue. But if it's in gear, It acts like it's running out of fuel and dying unless I roll into it easy but still can't go past half throttle when it starts sputtering.
At first - I thought it was fuel sloshing in the tank and starving the carb so I filled the tank and it still does it. Now this doesn't make ANY sense to me. How could it be leaning out if it's constantly leaking fuel out unless I cut fuel. Odd.... So I finished up, pull back into my driveway, turn the key, flip the choke... nothing happens.... Key is completely out at this point and it's still running like nothing happened. Double weird! Sat there for a minute or two just hoping that it would die as it started to rev up more and more like it was slowly running away. So I flip the choke back on and the idle drops back down... I know that most 2 strokes will rev up right before they die, but it wouldn't die AND I cut spark. Why is it Dieseling? So I cut fuel and it finally Dies.
I've got it to the point now that it will fire up and run just fine aside from not being able to rev too high in gear, fuel leaking when engine is off, and Dieseling.

Now to my Long winded question:
Is all of this caused by over fueling? Did I mess up the float plate causing this issue? My uncle has an identical polaris and he told me that his leaks a lot more out of the carb when it's off but doesn't have the other issues and mine has less miles at only 575.
Any help is appreciated. This whole story takes place over 3 weeks of long nights, google searches, and YouTube Videos.

 

Bump?

 

Hi fanman,
Have you had any luck resolving this yet?

 

If you haven’t figured out your run-on issue, You might want to check your wiring, on the Terminal board on left side under fuel tank cover (may have to lift up/remove tank cover to get to top of terminal board.There are two black wires at top of board,one goes to engine kill switch(you will know you have the wrong wire if key switch doesn't shut engine off) Just pull the black wire from the small limiter module