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<blockquote data-quote="SRAD97750" data-source="post: 232225" data-attributes="member: 425">For the carburetor you have, the idle mixture screw will be an air screw. Turning it in will make the idle mix richer, out to lean the idle mix.Mid throttle position is handled by the needle shape or needle jet ports, and anything beyond half throttle is controlled by the Main jet size.I'd clean the carburetor again really well, jets and all passages blown out with compressed air.&nbsp;If you're more than 3 turns out from lightly seated on the idle mixture screw, and still not lean, I'd step down on the pilot jet. And start again from 1.5 turns from lightly seated. You will eventually get surging or a hanging idle from revved up. That's too lean.If the dimensions of the inlet and outlet are correct, the 38MM Keihin could be a good swap. I have looked a the 39.5mm air striker as well for a mod on my bike. Fuel line and choke location may vary.Remember, if you do the carburetor swap, you'll have to go through the process of tuning it correctly, as above, anyway.-BIG DAN<img src="https://www.dirtbikeaddicts.com/static/images/smilies/thumb.gif"&nbsp; class="smilie" loading="lazy" alt=":thumb:" title="Thumb&nbsp; &nbsp; :thumb:" data-shortname=":thumb:" /></blockquote>

[QUOTE="SRAD97750, post: 232225, member: 425"] For the carburetor you have, the idle mixture screw will be an air screw. Turning it in will make the idle mix richer, out to lean the idle mix. Mid throttle position is handled by the needle shape or needle jet ports, and anything beyond half throttle is controlled by the Main jet size. I'd clean the carburetor again really well, jets and all passages blown out with compressed air. If you're more than 3 turns out from lightly seated on the idle mixture screw, and still not lean, I'd step down on the pilot jet. And start again from 1.5 turns from lightly seated. You will eventually get surging or a hanging idle from revved up. That's too lean. If the dimensions of the inlet and outlet are correct, the 38MM Keihin could be a good swap. I have looked a the 39.5mm air striker as well for a mod on my bike. Fuel line and choke location may vary. Remember, if you do the carburetor swap, you'll have to go through the process of tuning it correctly, as above, anyway. -BIG DAN:thumb: [/QUOTE]

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