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Need help - my bike chokes at the bottom!

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Hello,

I recently bougt a brand new crf450r and man was it fun to ride it the first time. It felt like the bike was designed by GOD just for me... I have had 2 x YZ250F and 1 x Crf250 so I was afraid my new bike would kill me on the first day, I just cauldn't believe the "crazy" feeling I got when I drove ahead into the track...

The handling is great, the powerband was great and I'm really thinking of selling my Race Tech suspension set, I just can't see the need for it. We also had Kawasaki kxf250 2005 on the track and we cauldn't even compare the suspension, the difference was so great.

BUT... that was the feeling I got on the SAND-Track, now it was time to go to the HARD-Track. When I started the feeling just got even better, the bike was great. THAN I begun to notice that when launching of a quick jumb (supercross stile) when I had to twist the throttle from 10% - 100% the bike always choked, causing it to drop the front wery hard (like beginners jumps crashes happen)- fortunetely by keeping the throttle wide open I cauld always safe the bike from going the "frontflip" crash - the weather was rather cold (about 2-4°C) and it had the original jetting.

Can anyone PLEASE help me so I can get the FLAWLESS Feeling again like in the sand ? 😢

Best regards

Johannes Mar

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Check your owners manual but on my '03 the stock position is 1 1/2 turns out. Turn it clockwise to lean, counter-clockwise to richen.

There's also a part that discusses jetting under different temperature and altitude conditions.

You may want to get one of the aftermarket pilot screws as it's a bit of a bear to get to the stock one.

When we rode CR500's, we would lean the needle (raise the clip) one position if it blubbered off the bottom. Not sure if anyone is playing with the needle position on the CRF's or if they're finding the pilot screw sufficient to clean it up.

Also, I'm not sure what you mean by it "chokes". Generally speaking, in cold weather, you want to richen the mixture.

Best of luck. 😢

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In the owners manual is a section on carb adjustment. I had the same problem. Bike would stutter when cold at the throttle stop and didn't idle smoothly. There are two screws....one is the throttle stop screw and is used to adjust the idle. It's the bigger one facing you as you look at the carb. The pilot screw is underneath the carb....It sticks downwards from the front bottom of the carb and is very small. You should adjust the pilot screw for temperature conditions first before you mess with the jetting needles. To adjust the pilot screw....turn it clockwise until it is lightly seated in. Record the number of turns......it should be 1 1/2. (That is the stock position) In general.....you want to go richer in winter and leaner in summer. To go richer you would turn it out 2 turns.....to go leaner you would turn it only 1 turn. As mentioned in another post.....1/8 turns will fine tune...but the screw is difficult to get to. Do NOT go more than 2 1/2 turns out....if you need to do this....you need to jet differently.... There is a chart in the owners manual that shows stock settings and different settings for temperature altitude. Good luck....I had to richen mine (2 turns out) to get it to idle better in the colder weather.

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