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Old 04-18-2013, 07:40 PM   #76060
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Joined: Feb 2006
Oddometer: 2,858
Originally Posted by mill View Post
No, the orings that seal the float to the carb body were dried out and cracked.
The only o-ring on a BST40 carburetor that can cause overflowing when it fails is the float needle seat o-ring.
Significant time restraints.
Perhaps this might help next time:
Yep, my DR650 is utilizing the the stock BST40.
BST40 carbs have cold start enrichment circuits instead of chokes. A choke is closed when an engine is cold and opened when it is warm, whereas a fuel enrichment circuit is opened when the engine is cold and closed when it is warm. A choke works by restricting the air flow, whereas an enrichment circuit works by adding extra fuel. A choke requires a fast idle cam or something akin to it (or you have to hold the throttle open manually), whereas an enrichment circuit adds a little extra air simultaneously with the extra fuel, so the fast idle is already built in.


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