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Old 05-24-2013, 07:58 PM   #1
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Gummed Up Carb Rotor

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I have an OS Max 4 stroke with a gummed carb rotor. Looking for the best solution to try and free it up. Any suggestions?

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Old 05-24-2013, 08:18 PM   #2
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Re: Gummed Up Carb Rotor

I got an OS .60 once as an Ebay purchase, supposedly had only a few flights then was stored for several years. Rotor was stuck solid. I thought for sure I had been taken. I gave a shot of WD-40 down the throat of the carb and left it for about 15 minutes, and lo and behold, it moved! It was just castor gumming it up and it has been a great engine.
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Old 05-24-2013, 08:31 PM   #3
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Re: Gummed Up Carb Rotor


Whenever I get a gummed up engine I suspect it was run with Castor oil. This is a good thing it leaves a slight coating of oil throughout the engine, but becomes gummy.

I just soak the engine in new fuel and very quickly it will free up. If it is just the carb, put some fresh fuel in the throat of the carb, put your finger over the carb opening, turn the engine up side down so the fuel comes back to the carb barrel, and very carefully move the throttle arm just a little at a time to work the fuel between the carb barrel and the carb body. It should free up.

WD 40 usually works as well, but typically does something to the glow plug and sometimes they give a problem after.

I hope this helps, let us know how you make out.


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Old 05-25-2013, 04:06 AM   #4
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Re: Gummed Up Carb Rotor

I use WD=40 until it loosens and then I remove the barrell and clean off all the tarnish and check the spring etc.and fuel inlet port.Also I normally have a wooden toothpick that I carefully use in some areas.
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Old 05-26-2013, 06:57 AM   #5
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Re: Gummed Up Carb Rotor

Thanks guys, soaked the carb over night in some glow fuel and now it's as slick as goose poop.

I do have one more question if I may. How do you get the varnish and crap off the muffler and cooling fins of the motor.

Thanks again
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Old 05-26-2013, 09:25 AM   #6
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Re: Gummed Up Carb Rotor

Just a little caution here, WD40 dries and turns gummy just like castor oil. The common after run oil is automatic transmission oil.

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Old 05-30-2013, 04:52 PM   #7
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Re: Gummed Up Carb Rotor

I inherited several 2c 4c glow models which did not run fro 4 years. I used Carburetor doctor ( CARQUEST or similar) to gently soak the carb throat, needle valve housing, valve train, camshaft housing (4s) for 20 min...runs like a charm. May need to gently break loose the carb barrel with pliers to get the cleaner into the patient, it will work. Disassemble as much as possible, soak in Carb Doctor and gently manipulate. Carb barrel will really gum up...don't force it.
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Old 05-30-2013, 09:57 PM   #8
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Re: Gummed Up Carb Rotor

For getting the varnish off the fins and muffler, I like the Dawn Power Dissolver. Very hard to find. Mail order may be the best in Canada. Second best I would say would be to disassemble most of the motor and use the dedicated Crock Pot with a straight antifreeze on low heat. Either way, a toothbrushing and they come out like new. They are still worn out, but look great. Don't leave them in the crock pot too long, too hot, or they go grey.
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