Reply To: Timing a 6HP Johnson 1989

[Don]

That small pointer #42 is the idle timing stop adjustment, this has nothing to do with pointing out TDC. The little pointer on the recoil is where TDC on the flywheel should be pointing to…
http://www.marineengine.com/parts/johnson-evinrude-parts.php?year=1989&hp=6&model=E6RCEC&manufacturer=Evinrude&section=Rewind+Starter
#21 in this diagram is the pointer where TDC on the flywheel should be pointing to…
Unfortunately, what you describe does not sound like a sync issue. I can’t remember which cylinder the fuel pump is plumbed into, kinda thinking it is plumbed into the top cylinder…Bypassing the fuel pump to check for diaphragm leakage was a great idea anyway…. The compression seems good, but compression numbers can be deceiving on two strokes. Sounds like the engine won’t run worth a darn at low speeds, how about at WOT? I’m guessing you are running it in a barrel so judging WOT power is kind of tough.
How about the darn primer? Those things are a royal pain, remember it has three positions…Off/warm up/prime. Oftentimes these things don’t get pushed in all the way and make the engine run rich/stall at low speeds. But, this would affect both cylinders, so it doesn’t seem like it is your issue. Easy enough to check though, just pinch off the little primer hose connected to the manifold while it is running.
Any signs of overheating on this engine? These have the lousy grommets, so surely suspect if the engine has been running hot. If it has been overheated, perhaps there is water leaking into the lower cylinder…Any signs of water on the bottom plug? Water droplets should separate out from the fuel on the plug when inspected, tapped in the palm of your hand. I suppose it is possible the lower seal is bad, but there are actually two seals in that housing…One seals the crankcase, the other seals the driveshaft splines…So, let’s just say the crankcase seal had failed, usually the driveshaft seal kind of takes over and keeps the crankcase sealed…So, this issue doesn’t seem likely, unless someone has been in there and really made a mess…
Could have a bad reed, or junk caught in one of the reeds…Popping the intake off isn’t too hard, but the darn recoil does need to be removed first. Keep in mind, that this engine really needs the airbox properly installed to run properly…It will probably bog/stall at high speeds if run without the air box. OMC over engineering at its/our best… I suppose there could be an ignition issue causing the bottom cylinder to misfire, but that isn’t real likely, but possible. Please don’t start replacing ignition components on a hunch, this just adds to confusion and expense. This engine does have the dreaded “UFI”, powerpack under the flywheel…You should certainly inspect the grounds and look for a damaged or melted ignition wiring harness. This engine has the coils with the push on primary leads…These connections oftentimes get corroded/loose, so that is something to look for. Disconnect the single plug stop switch lead from the ignition harness as well, these darn things can cause some real headaches. There aren’t alot of resistance tests to do on this engine, can only really test the coils. How about the plug leads? Those little spring terminals get rusted and cause open connections also…. Finally, what kind of plugs are you using? This engines require the champion “Q” plugs, or there may be misfire due to RFI interference.
Trying to think of everything basic and easy to check…Again, just doesn’t seem like a sync issue, especially if you haven’t really messed with any of the adjustments. You can simply pop the flywheel off if you are worried about the key being sheared…But again, a sheared key wouldn’t affect just one cylinder. Is this engine new to you? If not, when was the last time it ran OK?