97 Merc 200 carb, slow to plane out and no top end

Blake_F

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Aug 24, 2023
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I have a 1997 mercury 2 stroke V6 200 carbureted on my 18ft fisher bass boat. It’s ran great over the last couple years I’ve owned it. Put lots of miles and hours with not many issues. Recently I had a carburetor blowing out air and fuel so I inspected the reed valves and a few of them were chipped or broken. I’m sure they have never been replaced. I replaced the broken ones and put back together and she idled and started like a dream. Once I came out of the no wake zone and opened her up, it was very slow to get on plane, and would only top out at 40-45, I’m usually running 60-70. Brought it back and went back to the diagnostics. Checked throttle thinking maybe something got accidentally adjusted in the reed process, all carbs looks to be sinked and opening all the way. Checked compression and all turned out ok. Went to spark, all plugs firing. But when I did a drop test, top 2 cylinders have spark but no change in idle. This confused the hell out of me. I’ve heard of those bigger outboards with carbs idle on 4 cylinders then the other 2 kick in on high output, not sure if this is true or not?? Fuel seems to have no restrictions and is very fresh/clean. Took a flashlight to the reeds to check if something went wrong and those were all good as well. And ideas? I’ve missed most of the spawn and it’s really pissing me off lmao before the reed indecent, she ran fast, loud, and smooth like an old 2 stroke should
 

Chris1956

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Mar 25, 2004
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28,170
V6 Mercs do not have the 2+2 feature. Every cylinder on your motor runs continuously.

Reed valves almost never wear out. I doubt yours's needed to be replaced.

You might check timing at idle pickup and max spark advance. Maybe you messed something up when changing the reed valves.

Do all carbs get fuel? What do the spark plugs look like?
 

Blake_F

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Aug 24, 2023
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11
V6 Mercs do not have the 2+2 feature. Every cylinder on your motor runs continuously.

Reed valves almost never wear out. I doubt yours's needed to be replaced.

You might check timing at idle pickup and max spark advance. Maybe you messed something up when changing the reed valves.

Do all carbs get fuel? What do the spark plugs look like?
The reeds definitely needed to be replaced, about 5 were chipped or broken. Carbs are all getting fuel. Spark plugs are new, took it out again today and it doesn’t sound like it’s either not running on all cylinders or flooding. Really struggling when getting on plan that starts a heavy shake when I come off the throttle. But it won’t die
 

Blake_F

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Aug 24, 2023
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11
When I
The reeds definitely needed to be replaced, about 5 were chipped or broken. Carbs are all getting fuel. Spark plugs are new, took it out again today and it doesn’t sound like it’s either not running on all cylinders or flooding. Really struggling when getting on plan that starts a heavy shake when I come off the throttle. But it won’t die
did the reeds I put all new gaskets on made sure everything was put back the way it was. Not saying I did everything perfect but followed pictures accordingly that I took before hand
 

Chris1956

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Mar 25, 2004
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28,170
Reeds were stainless steel?

If timing is good, and spark on all cylinders, carbs are next possibility.
 

jimmbo

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May 24, 2004
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13,725
What were the Compression Numbers?
By Good Spark, can it jump a 3/8" Gap on all Cylinders?
 
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