08 kx450f only runs while choked

I have an 08 kx450f that will only start and idle with the choke on. I have never had any problems with it and it ran great when put away last year. When i got it out of storage for the first ride this year it ran fine for about 5 minutes then it started to act like the plug was slowly fouling. I limped it back home to change the plug and after i did it will only start with the choke on. As soon as I turn the choke off or twist the throttle it dies instantly. I have torn apart and thoroughly cleaned the carburetor twice. I have checked the float level and messed around the fuel/air mixture screw. After the last time I cleaned the carb I started it (with choke on) and after about 1 minute the exhaust pipe got so red hot that it melted the front fender.:thumbsup: Any ideas?

thanks,

Hayden

Sounds like a Jet problem to me, have you noticed if it's running hot at all? If so its likely running lean and needs the carb cleaned and or jets replaced. I'm not a mech but thats my 2 cents, good luck.

Greg

You have varnished you jets by leaving gas in the float bowl.

You need to remove the pilot jet and replace it, and inspect the main jet.

If it is all grungy in side the carb, you'll need to do a more complete cleaning.

just pull the carb and clean your pilot jet... simple as that... no reason to replace them... soak them in some b12 chemtool , small wire thru the jet and blow out with air... (i use welding time cleaners from LOWES) :thumbsup:

if ya dont sit there and saw back and forth with the welding tip cleaners youre not making the hole any bigger :busted:.......

work smarter not harder and save your cash.... :worthy:

also unless you put STABIL in that year old fuel CHANGE IT OUT ASAP .. that will make the bike run like crap just like a plugged carb.. (just went thru this with a customers VULCAN that had year old gas in it, carb was spotless and pilot was clear :confused:)

Clean carb. more thorough.

kx450f63, yeah waht he said

just pull the carb and clean your pilot jet... simple as that... no reason to replace them... soak them in some b12 chemtool , small wire thru the jet and blow out with air... (i use welding time cleaners from LOWES) :thumbsup:

if ya dont sit there and saw back and forth with the welding tip cleaners youre not making the hole any bigger :busted:.......

work smarter not harder and save your cash.... :worthy:

also unless you put STABIL in that year old fuel CHANGE IT OUT ASAP .. that will make the bike run like crap just like a plugged carb.. (just went thru this with a customers VULCAN that had year old gas in it, carb was spotless and pilot was clear :confused:)

You could do that. BUT the bevels built into each of the (8) holes are there to improve atomizing. If you damage one, you've got a dribble glass of a jet.

ok so I tore it apart again, took out all the rubber gaskets and o rings, replaced the pilot jet, main jet, and needle jet. Soaked the carb overnight in carb cleaner blew it out with compressed air the next morning and put everything back together then checked the float level. I then cleaned and oiled the air filter and put in fresh 91 octane fuel. No change. Any other ideas?

check/ adjust your idle adjustment on the carb.

Also check all your rubber fittings: from the airbox to the carb and carb to the intake.... If for some reason this fittings are loose you will be leaking air into the engine and your bike will only run when choked. this is a really common issue when guys pull their carb off their bike.

ok so I tore it apart again, took out all the rubber gaskets and o rings, replaced the pilot jet, main jet, and needle jet. Soaked the carb overnight in carb cleaner blew it out with compressed air the next morning and put everything back together then checked the float level. I then cleaned and oiled the air filter and put in fresh 91 octane fuel. No change. Any other ideas?

Hopefully, you did not use automotive carb cleaner. It destroys all the rubber parts.

You have not mentioned your hot start. Since you are in a lean condition (choke must be on to enrichen), I would look there first. The plunger gets corroded and can get stuck open.

Hopefully, you did not use automotive carb cleaner. It destroys all the rubber parts.

You have not mentioned your hot start. Since you are in a lean condition (choke must be on to enrichen), I would look there first. The plunger gets corroded and can get stuck open.

Usually when there is a hot start problem they start out by saying: "I went to clean my carb. and couldn't remove that cable thingy near the top of the carb."

Since he didn't mention anything to that effect I didn't think about it. At this point with the given info. he needs to double check all possible air leaks, including the hot start! Look through the idle circuit with a magnifying glass.

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