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Air mixture screw back its way out!!!


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got an 06 525 xc.

Riding a poker run today my after mkt mixture screw backed its way out to the point where it was hanging out and butted up against the engine. Thankfully it was long enough to go anywhere. Of course the bike sputtered completely out. Waited forever too cool off. Screwed it back in and it was good to go. Ran just fine afterwards so I assume the orrings are all in there that it needs. Is there some kind of greese or teflon tape I should use on it to screw it back in permanantly or should I just buy a new mixture screw?

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I would certainly check to ensure the spring, washer, and o-ring are in place. The spring does a good job a keeping tension on the threads keeping it in place. DO NOT USE Teflon tape grease or thread-lock or any quick fixes here. The fuel screw itself may be crap- threads are worn. The best fuel screws are brass- not aluminum- aluminum ones have been known to have their tips break off. Usually the reason why fuel screws fall out is because they are not screwed in far enough to hold in the threads and not enough tension from the spring. If your pilot screw is too small- you end up with this problem- if it is too big you end up bottoming it out on a cold day. the goal would be to have a pilot jet that allows for about 2.5 turns out from bottoming and running best.

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Two things to add:

1) On a 4-stroke its a fuel screw, not an air screw. Just thought I'd throw that in so you aren't thinking backwards when making adjustments.

2) Ideally you would want to be between 1 1/2 and 2 turns out, and usually no less that 3/4 turn or more than 2 1/2 turns.

If you are outside of that range you should probably change the pilot jet.

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it is highly possible you are missing the washer and the spring is not holding it tight enough.

i speak from experience on this one. i took my stock one out and put the spring on the new one. i was careful when i took out the fuel screw so all of the parts came with it...so i thought...the washer stayed up inside the carb, before i put the new needle in the washer had fallen out onto the motor. i put it all in and the oring seemed to hold it ok. so i adjust and go for a ride seems fine until about 30 min on the bike it starts bogging and sputtering and wont idle. i get off and look and same thing as you the needle is sitting on the starter totally unscrewed.

to get back home i screwed the needle back in and put a zip tie on it to the vent hoses to keep some tension on it so it wont turn out. i take it out latter and after chcking the book i realize it was missing the washer, problem solved... im a dumbass

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it is highly possible you are missing the washer and the spring is not holding it tight enough.

i speak from experience on this one. i took my stock one out and put the spring on the new one. i was careful when i took out the fuel screw so all of the parts came with it...so i thought...the washer stayed up inside the carb, before i put the new needle in the washer had fallen out onto the motor. i put it all in and the oring seemed to hold it ok. so i adjust and go for a ride seems fine until about 30 min on the bike it starts bogging and sputtering and wont idle. i get off and look and same thing as you the needle is sitting on the starter totally unscrewed.

to get back home i screwed the needle back in and put a zip tie on it to the vent hoses to keep some tension on it so it wont turn out. i take it out latter and after chcking the book i realize it was missing the washer, problem solved... im a dumbass

Yeah i recently cleaned my float bowl out. I must have been rushed and lost the spring as its way more loose than i ever remeber it being.

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