Reed Valve Sound Question

[Pleasure Boat Junction]

Hi,
I am working on a 1970 Evinrude 60HP. This is the same engine from previous posts that has a bad compression reading on the #1 cylinder, 135, #2 165, #3 160.
I can't get it to idle smoothly. It always seems like one clylinder is cutting in and out.
Yesterday I disassembled and cleaned the carbs. They were dirty, but are now cleaned (removed jets, soaked, cleaned jet in bottom of bowl with wire, blew out with compressed air, etc.) It runs a little better but idle is still rough and it seems to sputter at all speed ranges. Adjusting the idle jets don't seem to have an affect on the whichever cylinder is cutting in and out.
I checked the plug wires for continuity. They are ok.
I was rotating the flywheel by hand with the plugs out and noticed the top carb has a nice clean hiss sound on the intake. The #3 carb has a hiss, but is not as pronounced and has a wet oily sound. No sound is detected from the #2 carb. Could this indicate a reed valve problem with the #2 cylinder?

 

[F_R]

Re: Reed Valve Sound Question

That compression should be a clue. Consider the possibility that water may be getting in the cylinder. That could be from the exhaust cover or the head gasket. If it is water intrusion, it certainly would cause misfiring, and powerhead destruction (beginning with weakened compression).

Also, what spark plugs are you running? If you aren't running L77JC4 or QL77JC4, you should be. Even when new, those motors wouldn't run right on the useless surface gap plugs that it came with.

 

[Pleasure Boat Junction]

Re: Reed Valve Sound Question

Plugs are new QL77JC4 which "ezeke" recommended I use in a previous post.

 

[Benny1963]

Re: Reed Valve Sound Question

you may want to remove head as fr said there may be some damage on the low cylinder ,look for scuffing broke ring it will be easy to find after head removal

 

[Pleasure Boat Junction]

Re: Reed Valve Sound Question

Will do, but I'm also still concerned about no reed sound through the #2 carb?

 

[emdsapmgr]

Re: Reed Valve Sound Question

Weak reeds will contribute to low crankcase compression, and can lower head compression readings. You have a high (goog) reading on #2, so it's hard to point to a reed fault at this point. I'd run the engine without the airbox cover. If you get fuel/air blowback out of #2, the reeds are suspect. Water intrusion into the cylinders tends to be visible on the plugs. Water will wash them clean. Do all 3 of your plugs look the same after running?

 

[F_R]

Re: Reed Valve Sound Question

True reed problems are fairly rare. I'd go so far as to say that the reeds are probably one of the most reliable parts of the motor.

Disclaimer: If something got sucked in through the carburetor and stuck under a reed, that's a different story.

 

[Pleasure Boat Junction]

Re: Reed Valve Sound Question

I checked the old plugs and they are all about the same. There isn't one cleaner than the others. The new plugs have only been running in the driveway in a tank. It isn't on a boat right now. I am in the process of checking it out to see if it can be salvaged or if it should be junked.
I will check for blowback from the #2 carb.
It is very possible that something was sucked through the carb. When the #3carb was removed I found the broken off head from one of the airbox screws sitting behind it on what I believe is one of the reed valves.

 

[Pleasure Boat Junction]

Re: Reed Valve Sound Question

OK, Here is an update.
I just went to check for blowback from the #2 carb. The motor is cold. It has been sitting since yesterday. I hand cranked it just as before, but today there is reed valve sound from all the carbs! I'll try it again the next time it's warmed up to see if the sound from #2 goes away again.