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need help with k&b 3.5 outboard

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need help with k&b 3.5 outboard

Old 04-17-2006, 02:06 PM
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ehroof
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Default need help with k&b 3.5 outboard

hi guys, i have a tunnel hull with a 3.5 k&b outboard, it runs fine but the minute i put it in the water it stalls. doesnt matter if the idle is high or low. Any help would be greatly appreciated. i am affraid of overheating the motor so i dont want to fool with it anymore. Does is have a clutch?? the prop spins no matter what the idle speed.

thanks
eddie
Old 04-17-2006, 03:32 PM
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Default RE: need help with k&b 3.5 outboard

If the motor runs well at idle an then stalls immediately, or soon after launching, it's almost always because it's too lean. You want to set it so the engine sounds too rich on shore. Open the needle to somewhere around 4 to 4.5 turns to get it rich enough and try again. Once it will stay running, you can gradually lean it out.

Here's a page where you can find the owners manual: http://www.mecoa.com/kb/marine/marine_outboard.htm
Old 04-17-2006, 03:48 PM
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ehroof
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Default RE: need help with k&b 3.5 outboard

thanks chuck, should the boat be able to idle and not move in the water or must it move?? just trying to get it ready in my pool quick but the minute i put it in the water it runs for like a sec or two and dies, out of the water its fine but dont want it to overheat.
Old 04-17-2006, 04:14 PM
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Default RE: need help with k&b 3.5 outboard

It will and must move when in the water as it is a direct drive. Try the carb setting initially at 3-1/2 turns out from the bottom. You're going to want a slight lag when you blip the throttle while on shore. If it revs quickly, it's too lean.
Old 04-17-2006, 04:37 PM
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ehroof
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Default RE: need help with k&b 3.5 outboard

sorry if this is stupid but if the boat is idling and i put it in the water and hold it in place should it still run or die.
Old 04-17-2006, 04:42 PM
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Default RE: need help with k&b 3.5 outboard

It depends on how high that the idle is set but it might die. I give all of my boats a little underhand toss when I launch them. It got to be a habit especially after getting hosed down a few times from the roostertails.
Old 04-17-2006, 04:47 PM
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Default RE: need help with k&b 3.5 outboard

that may be my problem, i tried to let the boat idle and hold it without moving, even tried a high idle and had the same reaction, will try in a bigger area tomorrow.
Old 04-17-2006, 11:19 PM
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Default RE: need help with k&b 3.5 outboard

I have the larger version .67 on a tunnel and It doesn't idle at all in the water. I think the porting is kind of radical, not sure if the 3.5 is the same as the 11cc but if it is it will not idle very long under a load. I usually have to set my K&B at high idle give it a toss launch and then grab the radio and go WOT. After the boat is on plane its fine, but dies anything below 1/2 throttle even when underway. Toss launching also helps boat to get up on plane faster. This is part of the reason my newest boat is a gas motor (weedwacker motor) with a clutch in a Vhull. Not as fast but a lot easier on the nerves on take off and recovery. I have seen a seup for a clutch for the K&B 3.5cc on Ebay but not sure how great of a product it is. Do a search on this site as I think this is where I saw a post about the clutch setup.

Hope it helps

Old 04-18-2006, 04:05 AM
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Default RE: need help with k&b 3.5 outboard

ORIGINAL: ehroof

that may be my problem, i tried to let the boat idle and hold it without moving, even tried a high idle and had the same reaction, will try in a bigger area tomorrow.
Mine also won't idle in the water. These engines are not setup to run slow enough to allow the boat to sit in the water without moving. Trying to hold them still while the engine is idling will most likely do what you've experienced, kill the engine.
Old 04-18-2006, 07:27 PM
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ehroof
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Default RE: need help with k&b 3.5 outboard

thanks guys, i didnt get a chance to try it out today but will probably try it out tomorrow or thursday, i kinda thought that it needs to move in order idle but wasnt too sure, i am going on ebay now and gonna see if they have the clutch for it, it would make life a hell of alot easier.

thanks
Old 04-18-2006, 07:43 PM
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Ron Olson
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Default RE: need help with k&b 3.5 outboard

I've only seen one on there and that was a long time ago and was a prototype. It needed a lot of cutting to be done on the lower unit.
Old 04-18-2006, 09:16 PM
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ehroof
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Default RE: need help with k&b 3.5 outboard

no clutch anywhere, ebay, google etc. if the boat needs a push, so be it. will give it a try tomorrow. any other suggestions when i take it out, the boat doesnt have any trim tabs on it, can i try it without them? Do i have to keep the rpm's high and the boat going fast? any info would be appreciated, so i know what to expect.
Old 04-19-2006, 04:45 AM
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Default RE: need help with k&b 3.5 outboard

If you've got a tunnel boat that needs trim tabs, it's got issues. The only one that I've seen in years that had what we'd call trim tabs I found out that the owner wsn't using them for that purpose but as to artifically lengthen the hull to change the CG.

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