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03 300mxc, motor falls on it's face after half throttle

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So I got this bike with a blown motor. Rebuilt the top end and the rest of the bike. Started it up for the first time today. Second kick, fired right up like I rode it yesterday. Let it warm up and ran it through a couple of heat cycles. Took it down the driveway and it won't rev past half throttle. I know the power valve is timed right and the actuator arm is working. Air filter has no effect. It has new reeds. Had a new plug in it. Tried another one(br7es). My silencer is not stopped up and the pipe came from a friends bike that ran fine when he took it off. The slide is lifting all the way. Main is a 175 and pilot is a 45, for 79-100 F according to book. Book says 180 main and 48 pilot for todays temp. (50 F). it runs fine and comes on smooth down low. Starts up in gear no problem. After half throttle, it just falls on it's face. Going to pull carb and clean again. Possible electrical or crank seals? Any help greatly appreciated! Thanks JLow.

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Check gas cap vent, clogged vent can restrict flow at higher demand.

check all electrical system.

Check crank seals

Check needle position, too low too high?

good start let us know

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Checked gas cap and vent, fine. Needle in 3rd position. Not sure on the proper checks of electrical system and crank seals.

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What is the proper float level and what is the best way to check it? Checked the crank seals, no gas smell in clutch side. Removed stator cover and sprayed with contact cleaner while running, had no effect. Thanks JLow

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Put a 160 main in it today, screams on top end! Put a 165 main and tried again, still great. Going to stay on the richer side of things. Still had a mid range blubber unless I really clean it out, then it is okay for a few but loads up quickly on bottom. Has great throttle response and lift the front tire easily in fourth. Dropped the needle one position. Not much effect. Now just want it to run cleaner in the middle. Any input on needles anyone? Thanks JLow.

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It has the stock NOZH needle. In the 2nd pos. right now. Going to try Suzuki NECW and NEDW needle's per the guys on Ktm talk. What MJ is in your 300? They think my 165 is to lean. But it wouldn't clean out on the 170. Thanks JLow

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