[John Witt]

Okay so I have a 99 foreman 450s that while giving gas from 1/2 throttle to wot is sputtering as a rev limiter is stopping it. Things I have done. Brand new cylinder new cylinder head adjusted valves to .006 new carb new spark plug new pistons and rings new battery. I have ran the atv and checked plug it is blackened pretty bad it is snorkeled and has aftermarket exhaust it's running all the stock jets any ideas I am really puzzled. ?

 

[fishfiles]

Pull the top off the carb and check the diaphragm for a crack or hole in it ---you don't have to take the carb off to take the 4 screws out the top cover and pull it out

 

[fishfiles]

Welcome to the forums , just noticed it was your first post !!

 

[LedFTed]

Welcome; is your new carb OEM? is it adjusted by the book/manual?

 

[John Witt]

The carb is the cheap ones on ebay and is new it was having the same issue before the new carb

 

[John Witt]

Runs and idles fine anything past 1/2 throttle and it sputters

 

[fishfiles]

I bought a e-bay chinese carb for my 450 back when , never could get it right and had to buy a real one ------ replacing that junk would be the place to start ---- clean , fresh fuel in the tank , you may have put that new carb on and filled it up with the same junk that fowled the first carb --- a new spark plug is something that you should try

 

[John Witt]

I'll have to try take out the petcock filter only issue that bugs me is that it is running really rich even with stock 130 jets

 

[fishfiles]

how do you know the jet size ? you took the e-bay carb apart ? --- I think the biggest problem with the chinese carbs is they are generic and may be made to fit multiple applications , but not really jetted for every one

 

[fishfiles]

Still got you OEM carb ? clean it and put a kit in it ----be sure that diaphragm I mentioned isn't cracked of has a hole as it will do just what you described , fall on it's face after 1/2 throttle

 

[John Witt]

I'm still wondering with the oem is still making it burn super rich I was thinking stator or pickup

 

[LedFTed]

if ya get a kit, use shindy. hope its spelled right. dont rebuild the china carb, but the oem 1. how did your valves look?

 

[fishfiles]

$600+ is enough to make me want to learn something

 

[John Witt]

My valves are new

 

[fishfiles]

$600+ is enough to make me want to learn something

Wow , I posted this on the wrong thread !!!!

 

[misterclean59]

I think your snorkel is choking the engine. Remove whatever is necessary to disable the snorkel and see if it runs better. Removing the lid from the air filter comes to mind. You may need a new spark plug by now so I wouldn't trust the old one. If that doesn't do it then keep replacing the main jet will smaller ones until it clears up.

 

[John Witt]

Yeah I have had lid off with no effect I'll try jetting the carb down

 

[LedFTed]

could the choke be partially stuck? i'm grasping at straws. or even the timing be off?

 

[John Witt]

I made sure the choke is working properly and it did just undergo a rebuild piston rings cylinder and valves but I dont think we touched the timing

 

[fishfiles]

Seems you are all over the place , I would regroup , forget everything that has been done so far , start from the beginning to insure everything that has been done was right or is still ok and nothing changed ----------- do a compression test , then check the timing , adjust the valves , clean the tank , petcock and OEM carb throughly and put a kit in it so that you know you have the right jets , check the diaphragm for cracks or holes , check the manifold boot for cracks or a loose clamp , check the carb vent tubes , new spark plug ----I read where you have a snorkel , that could be your problem , which size and kind of pipe did you use ?