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post #1 of 7 Old 01-10-2017, 09:55 PM Thread Starter
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95 Big Bear 350 Carb Questions

I have a 95 big bear with a mikuni carburetor and unfortunately the previous owner tightened the fuel mixture screw down to the most lean setting and I ended up stripping the head off of the screw trying to free it up. Is there any way to play with the mixture by raising the main jet, I'm not sure if you can raise and lower the main jet on these carbs. When going from an idle to a pin, the quad begins to die and if I stay on it the quad eventually just quits, not 100% sure but that normally points toward lean. If anyone can help me out here I would greatly appreciate it. Thanks!
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post #2 of 7 Old 01-11-2017, 07:16 AM
 
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You need to get that pilot needle screw moving. Without this adjusted properly, the engine will never idle or excellerate correctly, no matter what you do to the main jet or main needle.
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post #3 of 7 Old 01-11-2017, 02:19 PM Thread Starter
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The quad doesn't idle bad but isn't consistent as it heats up and cools down, sometimes idles down or idles up. I have yet to check the spark plug to see the colour and see if it's lean or rich. I'll have to try again to get that screw moving but when I get it out it might have wrecked the seat being tightened down like crazy. If I get that screw out is it replacebale because it's pretty screwed up on the head. The quad is rideable and I've used it a while and I just have to ease on the gas instead of goosing it and after that I'm good to go. Maybe I'll have to buy a new carb if I can't get that screw moving
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post #4 of 7 Old 01-11-2017, 04:22 PM
 
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That screw is called the pilot needle, and it's replaceable. It will have a spring and O-ring on it, so be careful not to lose those parts if you take it out.
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post #5 of 7 Old 01-11-2017, 04:26 PM
 
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Might be worth a try to have the carb soaked in a carb cleaner like Hydroseal 2. It may allow that pilot needle to break free.
If you do this, make sure every peice of rubber or plastic is removed from the carb. You will need a new O-ring for the pilot needle after.
The Hydroseal cleans carbs very well, but can destroy some rubbers and plastics.
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post #6 of 7 Old 01-11-2017, 04:30 PM
 
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Something else to try as well. Use a fairly new or unworn screwdriver, and tap it into the pilot screw with a hammer. Do not drive on it, but hammering it a little might break it free. Additionally, those parts are brass, so the light hammering can sometimes drive the tool into it and give you a better grip to remove it.
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post #7 of 7 Old 01-11-2017, 11:54 PM Thread Starter
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I'll try that and hopefully it works I'll keep the thread updated as I go. Thanks!
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