07 YZ450 bog issue and hot idle

My good friend has an 07 YZ450 that bogs when you twist the throttle to say pick the front end up as you approach and obstacle in front of you. It didn't do this last fall when he bought the bike. We have cleaned the carb, done the o-ring mod as a cheap fix on accelerator pump spring to see if the Merge racing spring would help. Nothing seems to work. Also will not idle when it is hot.

Your slide needs some attention. There is a seal/gasket on the back side that wears out. Sudco has a rebuild kit.

Check your Ac Pump passage.....the one on the bottom of the carb body....with the float bowl off..Its the acc pump passage that goes through the carb body to the nozzle...If that bike sat for any period of time I bet thats clogged.

Have thoroughly cleaned the carb several times. I will check the slide seal.

The fact the engine won't idle hot is a clue in this issue. You need to try and figure out FIRST is the engine getting too much fuel idleing hot or is it starving for fuel ? Don't just go changing carb parts on assumptions from the internet it gets EXPENSIVE when you incorrectly replace a perfectly good part. When the engine is hot pull the sparkplug and see if it's dry or wet with fuel this will give you a clue as to what to check next. Does the bike restart easily after it stalls hot ? Does the bike have consistant power cold to hot running ? Do you see any blackish exhaust smoke on acceleration ? We need more details to accurately help....

Sounds like a rich pilot circuit to me. Does it seem to load up before it dies when it gets hot? What jetting are you running?

If you think its rich push your hotstart and see what happens. Does it clear up? If so its rich.

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