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Discussion Starter · #1 ·
I am new to this forum and would appreciate any advice. I bought a 2007 rancher brand new. I've had nothing but carburetor problems. Honda replaced the carburetor in 2011. More recently it would not idle. I had to adjust the idle screw constantly to keep it going. I had a broken valve seat. I got the head fixed , it still had trouble starting and wouldn't idle. Cleaned the carb. Same problem. Replaced the carb. Still same problem. It will idle too high one minute and die the next. Not sure what I am missing
 

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Is the carb genuine OEM or a Chinese copy? If Chinese, throw it away and start fresh with OEM.
If it is OEM, strip carb completely and buy an OEM repair/rebuild kit, follow the factory service manual for rebuild and setup procedure.
Also, was the timing set correctly after you valves had been repaired/replaced? Definitely worth a look. Check valve clearances whilst your at it too.
Does sound like a dirty carb to me though, possibly a bunged up emulsion tube, that can cause irratic idle and difficulties with starting. Do you have a photo of your spark plug at all? A lot can be told by the colour of your plug too.
 
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Discussion Starter · #3 ·
I have both a Chinese and original carb same exact problem with both. Although this is my first time tearing down this particular carburetor I became very efficient at it with the original one that came in it before Honda replaced it. The machine runs and sounds good. I have driven it at least 10 miles since replacing the head. It just won't idle
 

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Plug looks the same as mine did.. I had to ask the others here.. The diagnosis was running lean believe it or not.
I’d start a fresh with your OEM carb, get some small pipe cleaners and nozzle/jet cleaners and give that carb a real good going over. My betting is you have crud somewhere within the emulsion tube (the jet/tube with lots of cross drilled holes in it), ideally you need to blow through all the jets and passages with compressed air.
I even went to the extent of using wire wool and removing the corroded areas in the float bowl. I went to town on it, I got so annoyed with cleaning carbs lol!
Remember to fit a NEW inline fuel filter before refitting your carb again.

Refit with a new plug, or clean your existing plug, set the mixture to 2 1/2 turns OUT, be sure not to tighten the mixture screw in to much, lightly seated is just enough.
Tickover on a 300 is around 1200 rpm, I don’t know off hand for a 400 but it won’t be far off that I wouldn’t have thought.

Edit: I’d still be very tempted to check your cam timing and valve clearances.

Keep us posted.
 

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Discussion Starter · #5 ·
Got a carb rebuild kit and tommorow I will finally have time to rebuild and go through the original carb again thanks for the advice. I won't be able to check timing and valves but if this doesn't work that's my next project. I do have one question though, I couldn't get that little cover off so I just got my piston to tdc. If the timing was 180° off would it still run? I got the cover busted loose now and should be able to check it the right way
 
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