Cold miss....?

[dingbat]

1997 Ocean Pro 200

Starts and idles fine. No problem idling out of the creek. Hit the green buoy and go WOT to get up on plane. Pull the throttle back to 4300 rpm and we're off except there is an ever so slight on/off miss which clears in short order. Once cleared, it runs fine the rest of the day.

Thinking a carb is loading up from the the long idle out of the creek but I would expect the same behavior first time out of the hole after 5-6 hours of trolling (850-1,000 rpm), it doesn't.

Beginning to think it's possibly cold start related since it only happens in the morning. Excess oil from sitting? Stuck float?

Nothing shows up on the plugs. I guess it couldn't hurt to rebuild the carbs... but a lot of time and money into a maybe....

Any ideas....

 

[F_R]

Only an opinion, but I wouldn't mess with the carb since it runs fine except for that minor glitch.

 

[dingbat]

Only an opinion, but I wouldn't mess with the carb since it runs fine except for that minor glitch.

My feeling as well but...... too anal to ignore without a viable explanation

 

[jakedaawg]

Replace spark plugs

 

[dingbat]

Replace spark plugs

They're fairly new..... but something to think about. Had crazier things happen

 

[jakedaawg]

You could try a cold and then a warm compression test. Followed by cold cylinder drop test to isolate hole that's missing.

also might try running at dark to see if a plug wire is arcing.

 

[dingbat]

Turns out #2 plug that wasn’t seated properly. Compression ring not crushed.

compression is good. Changed all plugs since I had them in hand.

All plugs except #2 where a nice brown color though a little wet.

Still have a slight miss coming out of the hole first thing in the morning. Acts like it’s loaded up a bit from the idle out to the marker. Runs fine the rest of the day.

Guessing I have a float valve leaking although nothing shows up pressuring the carbs with the primer bulb

 

[racerone]

Picture of the # 2 plug ?-----Is the motor producing it's rated power on a dynamometer test run ?----That plug may hint at internal issues.

 

[dingbat]

Picture of the # 2 plug ?-----Is the motor producing it's rated power on a dynamometer test run ?----That plug may hint at internal issues.

Ran 216 HP the last time it was on a Dyno.

Thought I had pictures of the plugs.... guess not. I'll take some tonight

All plugs but #2 had probably had 70-80 hours on them. #2 plug has roughly 10-15 hours and wasn't seated, compression ring not crushed.

The thing that stuck me funny about #2 plug was half of the porcelain was starting to turn light shade of brown but the other half looked almost new.

The ground strap was a light brown, almost rust colored, to grey. Pretty consistent back to the base.

My first thought was water, but the condition of the top of the piston is consistent with the other two cylinders I checked.

 

[dingbat]

Picture of the # 2 plug ?-----Is the motor producing it's rated power on a dynamometer test run ?----That plug may hint at internal issues.

From left to right
Old #4 and #2 , New #4 and #2, roughly six hours on the "new" plugs. Five of them trolling @ 900 rpm

Notice the seal on Old #2 old isn't crushed