I have an 02 450 Foreman S. It just failed to start one day. I changed the plug and checked for spark, and it was good. It had sat for a few months, and the fuel smelled stale, so I drained it, pulled the carb, and put a kit in it. Now it starts and idles fine, but won't take fuel. If I bring it up gradually it will rev up, but if I mash on it, it will spit, sputter, and sometimes backfire. Have I got something out of adjustment? I set the valves, and the only adjustment that I see on the carb is for air. I might mention that I have the airbox and airfilter off, would it make a difference if I put that back on ? I need help quick!!!!! Hunting season is here!!! Thanks

 

Welcome to the forum. Taking the airbox and air filter off can cause it to run lean, and run poorly.

Also, it might not be getting fuel into the carb fast enough to keep up when at high throttle settings. I believe this model has a fuel screen, and you remove the petcock from the tank to get to it for cleaning.

 

Thanks for the input. I had the tank and drained it also. The screen didn't seem too bad. I'm going to try putting the airbox and filter back on it, and see if that helps. It seems to run better if I set the choke on just a tiny bit, so that would indicate starving for fuel I guess, but I have had the carb off of it about 3 times now, and like I said earlier, put a re-build in it, I thought maybe there was something I was missing, I'll keep working at it though !! Thanks again

 

Yeah, I'd for sure put the air cleaner back on and see how it goes.

If it is still running lean, I'd look for an air leak between the carb and head. Squirt a little spray oil around there while it is running, and look for smoke and a change in how it runs.

 

Ok ..... Thanks for all the help. Hopefully I'll be able to return the favor sometime.

 

Don't know if I was any help yet...

Stick the air box back on, and let us know how it goes.

 

Still no luck guy's !!! This thing has me baffled. I checked th valves again, they were fine. I had someone tell me that the vacuum slide sometimes will crack, and cause this to happen, so I installed a new slide,attached the airfilter, and box.......same thing !! idles great, and will take fuel gradually, but if I try and mash the throttle quick, it won't take it. I removed the choke, and it seems to run better. When the choke is installed, if I move just a tiny bit, it will take fuel, then other times all I have to do is barely move the choke lever, and it chokes out and stalls. Could all this be in the choke??? I don't have much knowledge on these carbs, so if someone does....please help!!!!!!!! Thanx

 

I would guess then that you have something clogged or messed up in the carb.

When you say you put a kit in it, did you install an aftermarket jet kit, or just a rebuild kit?

 

For a couple bucks, change the plug again.

 

Hey Jeff ! I have that carb apart about 5 or 6 times, if something is clogged, I wouldn't have a clue whwere it could be. I put a re-build in it, new o-rings, new jets, new needle and seat, new slide. I have soaked it in carb cleaner, and cleaned it the best I can. I am leaning towards the choke now. Something just doesn't seem right with it. I don't know much about these vacuum operated carbs. I'm old school..... the throttle cable did it all!!!!