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Discussion Starter #1
I am working on a big bear 350. I believe something like a 99 year.

All of a sudden one day I took it down the toad to go check some pasture fence and made it about a mile, and it shut off on me.I started it back up and the thing would barley run. It acts like it running really lean. So I put a new carb on cause it was never the best to begin with anyway. No change. I’ve tried adjusting it too.

If you have it in neutral and rev it up it revs and then maxes out way lower than it should if that makes any sense, and then started to bog and catch it self repeatedly and every biwif you keep the throttle pinned.

I then checked valve clearance, changed the spark plug, checked the timing, and no change. I replaced the Stator and pickup coil, and sealed with a known good CDI box and no change. I also swapped with a known good ignition coil and no change.

I could only get it to run right if covered 70 percent of the intake up with a piece of cardboard with the air filter out and can get it to rev up like it should.

I am at a loss here on what to do next cause I really like this little 4 wheeler and would like to keep it around, but it’s just not making sense to me as to why it won’t run right and why all of a sudden it would do this.

Any help would be appreciated, and I am new here, thanks in advance.
 

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I would think by covering the carb you are making it suck in more gas like choking it. Sounds like one of the jets are stopped up. Maybe the needle height needs to be changed.
 

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I would think by covering the carb you are making it suck in more gas like choking it. Sounds like one of the jets are stopped up. Maybe the needle height needs to be changed.
I can try adjusting the needle I guess, but all of a sudden it did this. And I would think with a new carb that it would not do exactly the same thing. One would think that the engine would at least run different.
 

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Blocking the intake making it run better shows you have a very lean mixture. Verify the jets in the new carb are correct. Then, with it running, spray around the intake manifold with contact cleaner. Any change in running indicates a vacuum leak. Sometimes the rubber intake boot can develop cracks.

Mad
 

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Discussion Starter #5
So I tried adjusting the needle to maximum fuel and no change. I’ve tried spraying around the intake multiple times and haven’t found any air leak.

What jets and where in the carbeurator? Will I have to pull the bowl off the carb to access them? I could swap the ones from t he old carb in and see if I’m that makes a change as the old carb is the original.
 

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So I tried adjusting the needle to maximum fuel and no change. I’ve tried spraying around the intake multiple times and haven’t found any air leak.

What jets and where in the carbeurator? Will I have to pull the bowl off the carb to access them? I could swap the ones from t he old carb in and see if I’m that makes a change as the old carb is the original.
Take off the petrol pipe at the carb; should flow freely. If not check in-line filter(if fitted) or take petrol cock off tank & check/clean in-tank strainers; also clean petrol cock; good luck!
 

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Discussion Starter #7
Take off the petrol pipe at the carb; should flow freely. If not check in-line filter(if fitted) or take petrol cock off tank & check/clean in-tank strainers; also clean petrol cock; good luck!
I have good gas flow. Checked that too. I’m at a loss on what else to check. Still not sure which jets in the carb might be suspect
 

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The jets are numbered on the side. Compare the ones in the old carb to the new ones. They might be too small. The slow speed jet will start with 0 and the main jet will start with a 1. Both should be 3 digits.
 
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