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2011 450sx-f help, please

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Ok, I've tried to search for answers on here and either nobody's had the same issue as me or I'm an idiot. Either way, I'd appreciate some help. I'm pretty much a 2 stroke guy... have had a couple CRF's and an RMZ's, but I really don't know $#!+ about 4 strokes.

I just picked up a leftover 2011 450sx-f. I babied it around for approx 90 min before racing a hare scrambles on Sunday. I rode on an mx track in anger for the first time yesterday and the bike was great. I rode again today and the temperature dropped a bit and I noticed the bike developed a bog. Off idle seems normal, but then when I go to roll the throttle through the meat of the power the engine chokes. If/when it pulls through, the power is not all there on top.

Is this what 4-strokes feel like when lean? Also, how do I know when there's too much noise coming from the engine. I noticed while riding mx (reving the bike a lot harder) there's noise coming from the engine when I get off the throttle. Just seems weird to my 2 stroke oriented mind.

Any help you guys can provide is greatly appreciated.

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What is your elevation ??

Try turning the FUEL screw out 1/4 turn and see if the bog gets better , keep going until the bog stops , the change in temp will affect the jetting , but if its jetted properly for your elevation the fuel screw should get you close enough , Fuel Screw: Out = Richer , IN = Leaner

If you have to go more than 3+ turns out from all the way in , the jetting is too lean , if you have to go less than 1 turn from all the way in , the jetting is too rich (its opposite of a 2 stroke AIR screw)

The Fuel screw is at the very bottom of the float bowl up in a recess , you might need to loosen the carb clamps (Intake,Airbox) so you can twist the carb as the starter is kinda in the way to get a screwdriver in

and 4 strokes are generally louder than 2 strokes , because of all the moving parts inside , as long as your oil is up and all , and it does not sound a lot louder than it did before , you should be fine !

Dont let it sit there and idle for 5 minutes either , 4 strokes heat up a lot more than 2 strokes because of the lack of oil in the fuel cooling the cylinder down

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