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Fuel/Air Mix Screw on 200 Honda Rebel CMX250C

424 Views 10 Replies 3 Participants Last post by  Bear_Lady
Why on earth did the design it with a tab so that it hits the float bowl?
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to prevent tampering with AF mixture which was set at factory to comply with exhaust emission standards yet allow for slight adjustment.
heating with soldering iron will weaken adhesive enabling tab to be removed from screw head..
It's not an actual tab that can be removed without grinding it off. Here is a picture.


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aluminum tab attached to top of brass AF screw..
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Here are two damaged AF screws with tabs removed
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After carb rebuild Honda even insists limiter cap be reinstalled after adjusting idle AF
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I didn't realize that was a cap.
The limiter cap also keeps the screw from vibrating loose and falling out. Not sure how or why it would happen but at least one member indicated it had happened to them.
With the cap it can't unscrew because of the tab hitting that fin on the float bowl.
Long before emission controls were required millions of Hondas were sold without anti-tamper limiter cap and AF screws didn't fall out..
Between the spring tension and o-ring resistance there is little chance of screw working its way out.

I remember the report of AF screw loss from forum member and questioned it's accuracy.
Often posters don't relay the whole story or realize the significance of one small part not reinstalled like the o-ring or metal washer..

My 87 never had a anti-tamper tab.. It is simply a screw without a large enough head to attach anything.
In all the years of riding it's stayed in place..
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I agree with questioning the AF Screw falling out and not expecting the washer or O ring not being installed. Those are small pieces easily missed during a rebuild.
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