87 Johnson 40 2 stroke. Upper cylinder boging down

[TylerToo]

My engine was running good this season until it started losing power. Top cylinder is is running poorly. Changed plugs, Coils, Wires. Cleaned carbs and swapped them. No change. Getting good fuel. Compression 150 on both. Any thoughts. Tkx

 

[racerone]

What fuel pump ?----If a conventional pump the diaphragm might be ruptured.----Easy to install a new diaphragm.

 

[TylerToo]

I dont think it's a fuel issue.
1 - Plug is wet
2 - See plenty of fuel coming out of the main jet
3 - Shoot fuel directly into carb and it floods
4 - Lower cylinder working fine
ThankThanks for the reply

 

[racerone]

Some simple trouble shooting is needed I guess.