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Starting my K&B 7.5

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Starting my K&B 7.5

Old 08-28-2005, 06:24 PM
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gatedude1
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Default Starting my K&B 7.5

I have purchased a used Prather lll Tunnel Hull . Have been into nitro for a few yrs with r/c offroad buggies so and have no problem starting my buggy engines but I guess things must be different with marine engines. Today I set everything up to get ready to take it to the local pond. When I recieved the boat the carb linkage was not hooked up because the cable was frayed so I put a new one on and proceeded to connect it up with the idle cup to the top of the carb. When I hit the throttle it opens counterclockwise. Is this correct for when I cranked it wouldn't start. Checked the glow plug and it was dry as a bone. It will start when I put fuel manually into the carb. Would one of you experienced fellows come to my rescue!!!!! Thanks, newcomer to r/c boating
Old 08-28-2005, 07:09 PM
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Ron Olson
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Default RE: Starting my K&B 7.5

Seeing how you are new with outboards, one thing always come to mind to me. Do you have your starter leads reversed? Even us that have a lot of time have done this one especially if we have both inboards and outboards. Outboards (Except for Thunder Tigers) run backwards. Check your fuel lines for leaks and to make sure that the pressure line is working.
Old 08-29-2005, 07:26 PM
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Default RE: Starting my K&B 7.5

Thanks for the help Ron. I took the plug out ,set the throttle open and cranked it with my thumb over the carb,no fuel came out of the head. I did this several times and each time I opened the high speed needle until I finally got a little fuel to come out the head. Put the plug back in and it started up and died again. Took the needle completely out and and blue blew into the pressure line. Fuel came out the top so I put it back in and blew again and there is hardly any fuel getting to the carb. Pinched the fuel line and blew and there were no leaks that I could see. I did check to see if I had the battery contacts on right and I did. The motor has good compression so I don't think it is an internal problem and by the way I have a brand new plug in it. Could it be some dirt or something has plugged up the needle valve assembly? Tommorrow I am going to replace all the fuel lines . Don't know where to go next. Thanks Doug
Old 08-29-2005, 08:45 PM
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Ron Olson
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Default RE: Starting my K&B 7.5

Check the fuel pressure nipple also for any clogs from oil, I've had that happen to me. That one drove me nuts trying to figure out.
Old 08-30-2005, 08:47 PM
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Default RE: Starting my K&B 7.5

Thanks Ron. Took the needle valve out and now it wont go all the way back in. Next Im going to repace the high speed needle assy.
Old 08-30-2005, 10:32 PM
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Default RE: Starting my K&B 7.5

Shoot some WD-40, carb cleaner or the sprays made for cleaning nitro engines. You might have something clogging up in there. The spray should go through with no trouble if it is clear.
Old 09-11-2005, 06:51 PM
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Default RE: Starting my K&B 7.5

I have had several 7.5 outboards. I have found that the carbs get things in them frequently and need to taken apart and cleaned thoroughly. just keep track of how many turns out the needle valve is set at. This seems to work on mine whenever I have had a problem. Also try lower percent nitro as this seems to make it easier to tune the motor.

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