Mercury KE7 stumped

[mercuryman]

My KE7 will start easy in a barrel but won’t run smooth running rich and surges. You can adjust mixture will smooth out few seconds them surge. Rechecked carb and float same trouble. I wanted the put Phelon mag on this motor did that same trouble. Took the AJ29ax off my KG4 tried it same trouble. Put the AJ19A off KE7 on my KG4 runs perfect so its not the carb. About 1 year ago I changed the crank seals, my notes say starts easy runs. Has 110 compression. What do you think is up with it.

[dave-bernard]

check for carbon build up. and fuel flow in the line.

[billw]

I would try new plugs. If that doesn’t work, take the same new plugs and close the gap down to .010 as a test. See if it runs better. The 20 cube Mercs will find virtually any reason to misfire at low speed. They just cannot take a joke. Everything must be perfect. I have found that closing the gap down below spec will tell a big story.

Long live American manufacturing!

[The Boat House]

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• This reply was modified 3 years, 3 months ago by The Boat House.

[billw]

I have got a KE7 that runs slow very well and it even has the Bendix ignition. But that run quality didn’t come without a fight.

Long live American manufacturing!

[RICK EICHRODT]

Check the in tank fuel filter.

[johng]

Dave and Rick might have solved the Problem. You are dealing with a 72 year old Motor. Unless you have a New internal Tank Filter trash the original and replace it with a filter in the Gas Line to the carb. Also I normally replace the Spark Plug Wires if original. Clean the Carb 100 % running small wire through all the orifices & passages.

[The Boat House]

[mercuryman]

This is embarrassing I think I caused the problem. I recently got a K46 two blade 8.25 X 9.5 prop and installed it on my KE7 , I had ask for ID help and was told its a KE7 racing pro. All the problems have been while running in a barrel . I reinstalled my AM191 3 blade 7.5 x 10 prop also for KE7 and it runs pretty good while in a barrel and will idle better. But thanks for all the suggestions I checked them all on my motor.

[Anonymous]

Motor was/is cavitating when running in barrel. Shows up more the higher pitch the prop has when coupled with a more aggressive the blade profile and the larger the diameter.

[Author]

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