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Posted

Bought a new carb for my 2001 Lakota sport 300, after about 3-4 weeks it started to choke down when giving it throttle. I find out that the diaphragm vacuum valve won’t open when I give it throttle, causing it to stay shut and choke out the motor. After opening it up to try and fix it, I can’t see what the hell happend! Does anybody know how to fix this or ever had this problem? Any input would be awesome! Thanks

Posted

There are only a few reasons for that diaphragm to not open.  One being there is a small hole in the actual diaphragm or it’s not seated properly. Two the air flow into the carburetor is restricted at the air filter intake. Three the neede at the bottom of the diaphragm is bent or not sliding in and out of the main jet properly. Four is the carburetor has gotten something inside the main vacuum port or oraface that allows vaccume to pull that diaphragm open “up”. 

The carburetor works on a vaccume system. When you hit the throttle it’s connected to a butterfly damper. The butterfly opens allowing air to be sucked into the carburetor which in turn has a small vacuum port that goes to the top of the carburetor that sucks the diaphragm up hence lifting the needle up allowing more fuel and air to mix and enter the engine. If that vaccume system is blocked or any one of the above listed items are compromised you will have a problem. I would bet the diaphragm is not seated right or has a hole in it. 

I attached a link for your use to see how this works. It’s worth a watch. You will have a clear understanding of how it works. 

Good luck. 

 

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