Skipping 44 cube old Merc

[fastjeff]

This one's got me baffled! Late 60s Merc 50 hp. Motor has new rings and seals, starts great and runs strong, but idles lousy, fouling the lower plug.

So far, I can't shift into gear without it stalling out on me, and even at higher than safe shifting speed. I have to fire it up in gear to go anywhere.

Also, running along at low speed, it blubbers like mad (fouled lower plug?) but this condition clears up when the throttle is opened. it then runs great--until dropping off plane to run at slow speed again.

Here's what I've done: Replaced the fouled lower plug (no improvement), then removed the rubber tube that goes from the lower bearing to the reed valve bolt ("A" to "B" in the photo). I plugged the hose that goes to "B" (the reed valve bolt) and left the other fitting ("A") open. This definitely helped, but the problem still exists.

In a word: HELP!

Jeff

 

[galamb]

Jeff, have you tried re-torqing the powerhead to the exhaust housing - try 20 ft pounds - sounds like she is sucking air, maybe through the base.

The other thing that comes to mind is a leaky lower crank seal. Especially since blocking the lower bearings oil supply (which would also block some air that would come along for the ride from the intake) makes a bit of difference.

 

[fastjeff]

Thanks. I'll look into it.

Jeff

 

[crankbearing]

Jeff,

Were they Brass or AL. Reed Cages. How were the Lambrynth seal on the cages. The bottom seal is a good place to start.

Dave