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fuel screw question

Posted: Sat Feb 23, 2008 2:50 pm
by xridgerider
Just curious how often people have lost their aftermarket one and if you have suggestions on how to NOT let it vibrate out. I bought the Kouba CRF's only one. But I am a little hesitant to install it. I have heard a lot of people losing them. Also heard to stretch the spring out a little to help it. Any advice would be great. Thanks

Posted: Sat Feb 23, 2008 3:17 pm
by Asmith
I have never heard of anyone losing a Kouba fuel screw, most lose the lousy aluminum ones.

Make sure it's not backed out more than 2 1/2 turns. If it is, change the pilot to the next larger size and start the fuel screw at 1 1/4 turns.

Some of the racers will adjust the fuel screw, then put a dab of silicone sealant on it. It will still allow you to move it when needed but will provide resistance to it vibrating out.

Posted: Sun Feb 24, 2008 12:54 am
by xridgerider
It is the brass one that I have. Thanks AS! I will give that a shot.

Posted: Wed Feb 27, 2008 8:24 am
by xridgerider
Hey AS, so I installed the fuel screw, but got another question. When I install the screw do I rotate it until it is completely seated and can't turn it any more? then back it out for my jet precision! I started it and it got tighter to turn so I stopped and backed it out alittle. Whats the procedure? Your help is appreciated. Thanks!

Posted: Wed Feb 27, 2008 8:28 am
by Asmith
xridgerider wrote:Hey AS, so I installed the fuel screw, but got another question. When I install the screw do I rotate it until it is completely seated and can't turn it any more? then back it out for my jet precision! I started it and it got tighter to turn so I stopped and backed it out alittle. Whats the procedure? Your help is appreciated. Thanks!


Make sure that it is not cross threaded. It should thread easily for 5 or 6 full turns.

Once you are sure it's not cross threaded, screw down all the way.

Then back it off the required number of turns for adjustment.

The CRF 250X with a 42 pilot jet should be around 2 turns out.

Posted: Wed Feb 27, 2008 1:53 pm
by xridgerider
Worked out perfectly. I also added a little silcone around the base of it. I have heard too many stories about fuel screws falling out, 50 miles into a ride. Norm Kouba makes nice products, I have met him before, he lives here in Idaho. Great guy. I suspect I will have good success with this. Thanks for the tips Agent. :D