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how to tune a k&b 3.5

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how to tune a k&b 3.5

Old 10-29-2004, 06:59 PM
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savageman22
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Default how to tune a k&b 3.5

how do you tune a k.b 3.5. I just got a boat and it came with a k&b 3.5 and i can not get it to start for me. its got alot of compression.i just can not get this thing to start or run. Also does the carb got a low speed needle. thanks[&o]
Old 10-29-2004, 10:39 PM
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Ron Olson
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Default RE: how to tune a k&b 3.5

It has just a high-speed needle only on most of them. K&B says to start it with the needle 4-1/2 turns out. Mine wouldn't fire until I went in to 3-1/2 turns then fine tuned it from there. It doesn't matter much but is it an inboard or outboard motor? New or used? A used one may have old fuel around the needle making it hard to fire. Is it getting any fuel? Is the plug good? Are you cranking the motor the right way? I ask a lot of questions but it's hard to tell a lot of things on the internet.
Old 10-30-2004, 07:08 AM
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Default RE: how to tune a k&b 3.5

It is used. it is an outboard. when i trying to start it fuel goes flys out of the carb and some to the starter can not turn it over because all the fuel it is get. the needle looks good. the glow plug looks good to me. thank you for your time trying to help me
Old 10-30-2004, 08:20 AM
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TERBObob
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Default RE: how to tune a k&b 3.5

First you need to make SURE that your glow plug is good . Bad plug and you'll never get her fired off . ( same is true if the plug is too cold of a plug for the engine and fuel )
Second .... if your shooting that much fuel out the carb's venturi , then either your exhaust line is plugged which is caused it to be primed , OR , you simply have the needle setting WAY too far open .
Good starting position is between 2 1/2 to 3 turns out .
Old 10-31-2004, 09:38 AM
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savageman22
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Default RE: how to tune a k&b 3.5

The glow plug is good. and it is not geting to much fuel. the exhaust is not pluged
Old 10-31-2004, 09:57 AM
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Ron Olson
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Default RE: how to tune a k&b 3.5

OK, I don't know how much experience that you have with OB's or R/C for that matter so don't feel insulted with any of mine or other responses. the K&B OB's turn opposite of other motors so make sure that your starter leads are reversed, black to red, etc.
Do you have a pressure line hooked up to the tank and is it to the right line? I ask this because someone I know (me) has done some really dumb things before by accident. Those are just 2 of many.
Old 10-31-2004, 10:18 AM
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TERBObob
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Default RE: how to tune a k&b 3.5

Ok , besides the things Ron stated ..... I would like to back track on something I said and also , what you said .

You :

I just got a boat and it came with a k&b 3.5 and i can not get it to start for me. its got alot of compression.i just can not get this thing to start or run

It is used. it is an outboard. when i trying to start it fuel goes flys out of the carb
me :

Second .... if your shooting that much fuel out the carb's venturi , then either your exhaust line is plugged which is caused it to be primed , OR , you simply have the needle setting WAY too far open .
Just curious , but if you never had it started , then how do you know that it is not getting too much fuel ?
It still sounds like either what I said , or what Ron has said .
have you tried removing the needle and making sure that it is the correct one ( meaning that is seats when all the all closed ) ?
I , myself , have picked up a used plane engine where the seller must have snapped off the original needle and replaced it with one that fit ( threaded area wise ) , but was not long enough to seat properly to close , so basically , it was ALWAYS getting too much fuel and flooding out )
Try removing the pressure line , closing the needle all the way closed , blowing into the pressure line , and see if your carb floods out ( it will come out the top )
Let us know the outcome ....
Old 10-31-2004, 02:36 PM
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savageman22
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Default RE: how to tune a k&b 3.5

I did not know you had to turn starter over back wards. the needle was bent alittle so when i turned it in it broke is if it was the wrong one when i get the new one i'll know. i did try to start it with the started going back wards and it still did not start. i got 4 nitro cars and trucks so my tuning is pretty good but i have never have had a boat engine so it must be a big differences in car and boat engines. thank you for your guys time
Old 12-07-2004, 10:14 PM
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Default RE: how to tune a k&b 3.5

This may be way too simple...Is the starter going the right way?
Old 12-10-2004, 04:55 PM
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Default RE: how to tune a k&b 3.5

yes it is

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