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fuel screw question

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The screw has a small tapered pin on the end... the further out you turn the screw, the more fuel is allowed through the orifice, thus, out makes richer.

General wisdom is to turn your fuel screw in until the motor starts to idle roughly and turn the screw out about a quarter turn. If you need to run your fuel screw out more than 3 turns, you run the risk of the screw falling out due to too little spring tension, so you should go up one size on the pilot (slow) jet. If you are less than one turn out, you might need to go one size down. This fuel screw and pilot jetting circuit is critical to starting and idle. Many CRFs are hard to start because they are too lean on the pilot jet. A note to the wary: There is a small spring, a tiny washer and an O-ring on the tip of the fuel screw. Keep track of all the parts! I had an O-ring get wedged into the slow circuit and couldn't get the bike to start at all, until I dug out the O-ring and replaced it.

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The screw has a small tapered pin on the end... the further out you turn the screw, the more fuel is allowed through the orifice, thus, out makes richer.

General wisdom is to turn your fuel screw in until the motor starts to idle roughly and turn the screw out about a quarter turn. If you need to run your fuel screw out more than 3 turns, you run the risk of the screw falling out due to too little spring tension, so you should go up one size on the pilot (slow) jet. If you are less than one turn out, you might need to go one size down. This fuel screw and pilot jetting circuit is critical to starting and idle. Many CRFs are hard to start because they are too lean on the pilot jet. A note to the wary: There is a small spring, a tiny washer and an O-ring on the tip of the fuel screw. Keep track of all the parts! I had an O-ring get wedged into the slow circuit and couldn't get the bike to start at all, until I dug out the O-ring and replaced it.

So do suggest something larger than a. 42?

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If you're more than 3 turn out, you can take it up to a 45. 44 would be perfect, but they don't make them.

Just to add to the thread by Grinstead_77G, you can't purchase the o-ring, spring and washer by themselves. You have to get the whole assembly with the mixture screw. It's about $20 but that's pretty expensive for the 50 cents worth of little parts you need.

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