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Discussion Starter #1
I have a 2000 trx300fw it appears my spark is not conistant. It will start and idle at first but then started to surge. Anytime u try to give it any throttle it will burp through the carb and shut off. I'm at a loss. Have checked timing and replaced the pulse charger beside the stator. Any help would be amazing. Thanks
 

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You first need to determine if it's a fuel or spark issue. Surging usually indicates a lean condition in the carb, but a weak spark will cause many similar symptoms of carb issues.

Take the spark plug out and close the gap to about .015 or .020" - if it runs right, then the problem is definitely spark related. If it runs the same, dump the fuel into your car or truck and try a fresh fill of 91 octane (or higher) non-ethanol fuel. If that doesn't change it, have the carb thoroughly cleaned. It's kind of a witch hunt when you have this type of problem.
 

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Discussion Starter #3
Ok so I tried closing my gap and nothing really changed I just soaked and cleaned the carb yesterday and already have non ethanol 91 in it. When u adjust the screw on the bottom of the carb nothing really changes either
 

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If adjusting the screw does not affect idle, you either have an air leak or the carb is not completely clean. Did you remove the pilot jet and fuel screw when you cleaned it?
 

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Discussion Starter #5
Yes I had all screws and all jets out. I soaked it for 24 hours or better and then sprayed wit cleaner and blew it out real well.
 

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Usually, if it will start, but not accelerate, the problem ultimately comes down to bad gas or a carb problem - most ignition problems result in no spark or breaking up at the upper RPM's

Try choking it when you accelerate or spray fuel into the intake as you accelerate - if it seems to accelerate normally even just temporarily - it's probably a carb (or fuel) issue.
 

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Discussion Starter #7
So I have tried everything suggested however when I accelerate nothing really happens except a lil backfire thru the tailpipe. I've tried spraying carb cleaner while accelerating and no change any ideas?
 

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Spray carb cleaner can damage the slide vacuum diaphragm - check the diaphragm and if it's OK, try spraying something other than carb cleaner while trying to accelerate - a real fuel substitute like ether would be good. Carb cleaner is not usually highly volatile.
 

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Discussion Starter #9
Ok so I have also tried that. I am almost leaning more towards some sort of spark issue. The fourwheeler does start and idle for the most part but is not smooth. I have tried two different carbs and no change. I have tried two cdi boxes and a new little black box beside the stator. I'm at aloose. Usually pretty good wit these motors but this one has got me
 

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Discussion Starter #12
I have put a spark tester on it and seems the spark is very erratic. What could be causing this. Checked all wires and fuses all appear to be good
 
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