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K&B 7.5 inboard carb

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K&B 7.5 inboard carb

Old 08-13-2007, 10:15 PM
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rb110103
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Default K&B 7.5 inboard carb

I have a K&B 7.5 inbd that runs really well, the problem is that it wont shut off using the remote. I have to put my thumb over the carb to shut it down. The carb has only one needle for adjustment. I guess what I need to know is how old this motor is and If there are still carb's available for it. The engin number is A0001012. Take a look at the pics and please tell me what you think.
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Old 08-13-2007, 10:33 PM
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Dan S
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Default RE: K&B 7.5 inboard carb

rb,

before you spend money on a new carb, when you try shutting off check the barrel in your carb to see if your servo is closing it all the way.

make sure your servo has enough travel to do it.

Check it by hand also, rotate the barrel to the close position, if you can't close it adjust it with your barrel stop screw ( the one with the spring ).

Dan.
Old 08-13-2007, 10:46 PM
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Default RE: K&B 7.5 inboard carb

Thanks for the reply Dan, I bid every thing that you suggested and it still runs even with the barrel is rolled closed. I tried adjusting the screw with the sping on it almost all the the way out and back again rolling the barrel and it still ran. The servo was working like it is suppost to. You would think that if you cut the air to the engin by closing the barrel it would stop. It dose not have a low speed needle would that have anything to do with it?
Old 08-13-2007, 11:02 PM
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Default RE: K&B 7.5 inboard carb

make sure when you close the barrel that it doesn't go too far, if it does, it will start opening again at the bottom, giving it air supply and not shutting off.

There could be a leak somewhere, I'm doing a search right now on that engine.
Old 08-13-2007, 11:23 PM
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Default RE: K&B 7.5 inboard carb

I have been looking for this engine for the past hour with no luck I hope you have better luck.
Old 08-13-2007, 11:26 PM
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Default RE: K&B 7.5 inboard carb

your engine is an early model 9181.
they came with a black, gold, or red carb. I can't find anything about a purple carb but the carb could have been anodized purple.

Check these links:

http://www.mecoa.com/kb/87/9181-exp.pdf

and

http://www.mecoa.com/kb/carbs/carb35.pdf

and

http://www.mecoa.com/kb/parts.htm

ensure the barrel stop screw is working, you don't want to be able to spin the barrel all the way around. ensure your servo closes it clockwise.

Dan.
Old 08-13-2007, 11:38 PM
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rb110103
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Default RE: K&B 7.5 inboard carb

Thanks alot Dan!! I really appreciate your help
Old 08-14-2007, 12:03 AM
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Default RE: K&B 7.5 inboard carb

The purple carbs are very rare, they where the first run than after that the color changed to red, we don't know why.

The specs are the same as the red carb.

Dan.
Old 08-14-2007, 12:59 AM
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ob nut
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Default RE: K&B 7.5 inboard carb

There is a small hole used for the low end. Cover that up (tape) and it should help stop the motor.
Old 08-14-2007, 10:26 AM
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Default RE: K&B 7.5 inboard carb

ob nut is right,

I just found that out this morning, no LSN, its an air bleed system.

if covering the hole doesn't work try to find a more recent K&B Red or Gold carb with the disc system for the LSN.
Also the earlier carb were a bit sloppy and did not always make a good fit when bolted in, sealing it should also help.

Dan.
Old 08-15-2007, 10:05 AM
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Default RE: K&B 7.5 inboard carb

Believe those motors only came with either the purple or red. Purple is rare, as Dan S points out. You'll normally find them with red carbs. Don't think they ever came with the black carb, which was only on the 3.5 OB's. Yes, they do interchange.

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