Riddle of engine falure

"I am not sure what went wrong

"I am not sure what went wrong. The story is: the motor was running pretty good. Occasional stall at low rpms, some times ti would take a few seconds longer to rev down after running at higher speeds but nothing majorly wrong. Against my wife’s opinion(don’t fix what isn’t broken) I decided to put in Boyesen Power reeds to see if I could get a bit more out of the motor. This is where it gets iffy. Before I took the motor apart to do the reeds I ran the Evinrude de-carb engine tuner through it. Having rebuilt the motor myself two years ago I figured I would have the new reeds swaped in quick, and the decarb could do its work in the mean time. Unfortunately I got the motor apart and realized that it had 6 peddle reeds and the ones I had received were 5 peddle. So it took 5 Days to get the new reeds in and all the while the decarb was sitting in the motor. Not sure if that caused anything but just letting you know the whole story. After getting the reeds in I took it to a local shop for a Link and Sync. They ran it for 20 min then said it lost spark and I needed a CDI box, bad luck I guess. Once they put a new one on and had spark, they said that I had an air leak and they wanted to take off the carbs and intake to make sure that I didn’t make a mistake. Also they said that the recirculation hoses were routed wrong and changed them. Which I am not sure of because it ran for two plus years the way they were. After redoing all the gaskets and checking the reeds they said that they still had a lean condition in #3 cylinder. They tried swapping carbs around and still a lean condition on #3. At this point they said that it must be and internal air leak because they tried spraying carb cleaner everywhere to see if they could find a leak around the block or anywhere. I ended up picking up the boat and it was coughing and sneezing badly. I took it over to another mechanic friend of mine who sat there with it in the lake and adjusted the carbs and timing and got it to calm right down. It was purring like a kitten at idle and ran great up and down the lake three times. The next day I ran it on a long trip and after about 30 minutes at 4000 rpm it suddenly lost all power. I took the motor apart and the top left piston when standing behind the boat is trashed. I think its #2 if I am not mistaken. I just cant figure out how replacing the reeds can all of a sudden cause all these issues. And I am not sure how to figure out what caused it. Sorry for the long story but I am at a loss. Any thoughts would be greatly appreciated."

"de carb products were not the

"de carb products were not the cause of the failure,they will only break down carbon deposits
and sitting for five days,its possable that most of it dried up(evaporated).
adding power reeds can change mixture/lean in some cases,jets should be considerded.
cdi box those things can just go when they feel like it,my best guess is you may have had a problem with carbs,(dirty)because just spraying carb cleaner to find an air leak or try to clean them is not a very good way to find an air leak or clean anything other than a little dirt / grease .a little soap and water in a spray bottle will make bubbles.
(externally)
thats my "

should I oversize the jets whe

should I oversize the jets when I put it back together or how will I know that I need to? I thought that sir leaks would be sucking air into the motor so would you even see bubbles wiht soap and water? they said that by spraying carb cleaner if there is an air leak you will hear the motor change rpms when you hit the spot that it is sucking in.

"that would indicate a bad gas

"that would indicate a bad gaskit or engine seal
there are only 7 places on the out side of the engine for this to happen carb to reed case,reed case to block, and case halfs(that would be bad gel seal)doubt that.crank seals upper ,lower,heads. gussing you are doing rebuild,there is no telling what you will need,until its done,do a proper break in /watch plugs for proper color.
do a complete carb rebuild/make note of jet size,
(prob stock)back to the carb cleaner thing,(you say it will change rpm when the spot is sucking in )that would affect the entire engines performance,not one or two cyls,when 2 cycle engines operate they compress and create suction,to create power 2 cycle,a leak in the suction side would cause poor fuel delivery /cause for poor idle (leaner in all cyls),a leak on compression side would cause lower comp and would make it rich(plugs black /wet w fuel)
i really do not think they could spray the crank seals because its impossable.
that is just my understanding of the subject if anyone else cares to jump in on this please feel free "

I would say that you had the c

I would say that you had the condition all along with that piston and it was just bad timing that it let go when it did. The occaisonal stalling is a sign that something was amiss. I got my 200 yami a bit hot by sucking a plastic bag. It ran fine the next few trips except it would stall on occasion when shifting into gear at idle. Never did that prior to the overheat. It should have been a red flag. A week later I melted a piston while running in from a fishing trip. A small amount of water was getting into the cylinder and steamed the piston.

thanks for the help guys I rea

thanks for the help guys I really appreciate it. aAll other cylinders look perfect so I will definatly go through all the carbs and rebuild them. when you put the gaskets for the intake and reed boxes do you ever coat them with any kind of gasket sealer or is thet not recomended?

ues the john/rude sealer compo

ues the john/rude sealer compound as needed.
we have a nick name for it (gorilla snot)
you will find out why

Permatex makes a removable sea

Permatex makes a removable sealer called Hylomar that i've come to like lots better than the traditional stuff (P'tex #1 & 2 and RTV). you can put it on thinner so less chance of clogging something when using around carbs & intake. pricey but good stuff.

"Hi mate dont use anything oth

"Hi mate dont use anything other than the OMC sealer it was made by the manufacture to do that specific job. A tip when applying the gasket sealer is place the gasket on some cardboard and coat the gasket both side and you wont get any excess or anywhere else you dont want. Rebuild the engine, check the timing!!! i would retard the timing slightly befor you run the engine might just save some heart ache until you time the engine on the water"