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Starting point for an old 7.5 KB outboard

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Starting point for an old 7.5 KB outboard

Old 06-15-2016, 08:40 AM
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wholehog
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Default Starting point for an old 7.5 KB outboard

Hope all is well with everyone. Just finished up a complete restore on a tunnel. It's got a good but old KB 7.5 for it. The carb is square and silver, there is the high needle on the fuel inlet side, there is a idle speed needle on the opposite side (bottom) and where the cable ties in on the barrel there is a idle mid range needle. What is a good starting point for this needle? Thanks
Old 06-15-2016, 11:09 AM
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Hydro Junkie
 
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That sounds like a question for Jerry Dunlap or Mark Scott
Old 06-17-2016, 12:41 PM
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wholehog
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Originally Posted by Hydro Junkie View Post
That sounds like a question for Jerry Dunlap or Mark Scott
Can't seem to find them here HJ. Does Jerry have a call sign he uses? Thanks
Old 06-18-2016, 07:36 PM
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Ron Olson
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Jerry Dunlap pops in here once in a while and Mark "ob_nut" Scott also stops in here but not a regular. Search using last names in the tool bar above.
The screw by the barrel is an idle speed screw, usually you leave that one and the low-speed needle alone. Try the high-speed at 4-1/2 turns out and go from there. It's always a rough setting depending on the percentage of nitro you're using and weather conditions.
Old 06-21-2016, 03:00 PM
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That is a good question. Sorry to state, but I didn't get into 7.5 until the Red Head came out. At that point, the low end needle was converted to the round slide. All my current 7.5 carbs are all mod'd in some way. Basically, the low end needle is gone. Don't need it since racing is normally done at full open. I can post pics tomorrow when I'm at home. Sorry, but I can't help on this question.
Old 06-22-2016, 11:49 AM
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Had to go thru the junk pile to find the old style carbs. Two had been mod'd by the previous owners as the low end were sealed off. The other two carbs had the low needle at 3.5 turns out.

The carbs I'm using now are mod'd as such:

Old 06-27-2016, 08:02 AM
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wholehog
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Thanks a bunch, sorry for the late reply, just got back to a computer.
Old 06-28-2016, 09:03 PM
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Go to Mecoa they have a good page on carb settings I run old 7.5 s all the time I start with the low needle set flush with the carb arm and the high needle set a four turns out and tune from there I usually run 20% nitro and 16% oil back yard basher mix I just play so I'm not ringing every last bit out so I'm usually on the fat side

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