Stock 400ex won't idle & bogs out..........
 

......when 1/2 to full throttle is applied. It ran fine then just started running like this. I put in a new plug and tore the carb apart and cleaned all the jets, needle and diaphram. Checked the clearance on the intake (.004) and exhaust (.005) valves and all four seemed to have the proper clearance. The bike also spits smoke and sputters when the throttle is applied. When it gets dark you can also see flames shooting out of the pipe. Any help would be appreciated. Need to get this thing running right in the next week or so. Thanks.

Stock 400ex won't idle & bogs out..........
 

sounds like Ignition timing is off. Could be the advance part of it. check it with a timing light and see what you find. If the timing is off then you need a new ignition module.

Stock 400ex won't idle & bogs out..........
 

maybe stretched timing chain?

Stock 400ex won't idle & bogs out..........
 

it could be losing compression

Stock 400ex won't idle & bogs out..........
 

sorry about the bad luck............


hope it works out

Stock 400ex won't idle & bogs out..........
 

oh also check your battery connections, my positive wire got loose and caused it to not idle and when it was on the lights would dim really bad when i revved it.

Stock 400ex won't idle & bogs out..........
 

My wifes 400ex went threw the same thing. Hers was a small piece of sand in the fuel air screw. I just turned it out all the way then screwed it in back to were it was set before and it runs like a top now.

Stock 400ex won't idle & bogs out..........
 

check your headgasket my head gasket had a leak and did the same thang yours is doing i kept messing with it till i finlly took it all the way apart to find out my piston , rings ,and cylender were trashed so i would advise you to make sure your headgasket is not leaking befor it is to last hope for your sake it not the samething mine was if it is get a je 416 piston and bore it out not hard to rebuild honda motor...goodluck