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Discussion Starter #1
My 335 surges, I have cleaned the carb, replaced the fuel filter and fuel line. The only thing left is the fuel pump. What is considered good flow rate on these motors?
 

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The manual says its 2.2oz in 15 seconds running at fast idle.

You mentioned cleaning the carb, I assumed that you adjusted it as well.

Surging could be a vacuum leak as well.
 

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There are so many articles about the Mikuni carbs and how they will surge if they are partially blocked. Stop and think about how a carb works. The bowl fills up and then the float shuts off any new fuel from entering. The pressure from the pump along with vacuum keeps the fuel moving through the throat of the carb. If the bowl drops too low then the engine will shut off or if there is a partial blockage in the carb it will get a lot of fuel and then not enough. Then you have a surge. I've had several carbs that I could not fix and just bought new ones. That has solved the issue every time. Not saying you can't clean the carb but it isn't easy and maybe not be worth the effort. Many here, including me, have taken all of the jets out and run small wires through the ports. Sometimes that works other times it doesn't. If time is not a concern give it a shot by completely taking it all apart and see if that will help. It definitely is a carb problem.
 

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Discussion Starter #5
I figured it is a carb issue, just checking all boxes. As far as I know this carb is not adjustable.
 

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O.K. now this is strange, I am now seeing what appears to be water in the throat of the carb coming from what I believe is the crankcase breather.
 

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Discussion Starter #9
Just a follow up, when I started this journey the vent on the fuel pump was caked up with crud and I thought blowing it off would be good. Took the pump apart and blew the vent out from the inside and now it runs like a champ.
 
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