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zack250

2008 yz450f stall

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hey guys, i recently rode my buddies 08 yz450f and its the first time i rode a 450 and man does it pull hard! but when i slow down and come nearly to a stop it will stall on me and i have no idea why. its already warmed up and running fine. it also only has between 5-10 on it total

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Such is the nature of a modern 450 MX bike.

A light crank & flywheel plus a tall first gear makes them very high-strung.

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yea it stalls when i have the clutch in, i did turn the idle up a hair but not much and it still occured. might have to turn it up more. and are all 450s that sluggish in low rpm? my 250f took it off the line

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haha yea i have a 250f now and when i pay this off i was planning on getting a 450 but now, i think im gonna go back to a 250 2-stroke after this bike!

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yea it stalls when i have the clutch in, i did turn the idle up a hair but not much and it still occured. might have to turn it up more. and are all 450s that sluggish in low rpm? my 250f took it off the line

Something doesn't sound right if it stalls when the clutch is pulled IN.

450's aren't usually sluggish off the bottom.

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Does it still have the stock exhaust? They are very restrictive. I'd also check the main jet and pilot jet. If the bike has sat very long it's possible the gas gummed up and partially plugged the jets. The '08 YZ450 does require that your keep the rpm's up to work well just like a 250f. If you let the rpm's drop too much and in too high of a gear it likes to cough and die.

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He needs to change the pilot jet and add the accelerator pump cover. Had the same thing on the 06 and that fixed it.

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yea i was thinking a jetting issue also, ill tell him to check that out. and yes he still has the stock exhaust for it.

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