Johnson 3.0 timing trouble.

[Freedumb]

I have an old Johnson 3.0, that I got for free. After a tear down and clean up I got it back together and it had no spark. I cleaned the contacts w/ some sandpaper and Starter fluid. The Carb is cleaned out thoroughly and is delivering fuel to the cylinders. It has good spark now for sure(found out the painful way) and I slipped in some brand new plugs. It ought to have everything she needs. However I don't have the timing right I guess, I cant get her to pop off. I forgot how the flywheel goes on and which plug wire goes to the top cylinder. One of the wires has a metal clamp on it. There are two marks on the flywheel. I need to know what they mean and how they relate to the throttle position any info will help. Thank you.

Aaron aboard Ophelia

[mgoller]

Hey Aaron,
What is the serial number?  Should be on a metal plate stamped and on the motor.  Something like 3R-78?  That would help.
The wire with the metal clamp is the top cylinder.  The flywheel should have a key and only go on only one way.  Don't worry about the marks on the flywheel.  These engines have a fixed timing.
Point setting should be 0.020", that's standard.  With the flywheel off adjust points with the cam lobe at its highest point.  Make sure your feeler gauge is free of any oil.
Spark plugs set at 0.030", probably J6J plugs.

Squirt some fuel into the carb throat and try starting.  Sometimes you're not getting fuel delivery when you think you should be.
That spark has to be a very bright blue crack.  At speed and with compression it is harder for the spark to jump.  If the gap isn't set right it may spark out of engine but not under compression.
Yellow is no good, has to be blue spark.
If not replace the old coils and points/condensors under the flywheel.  They don't cost much and the new coils put out twice as much power as the original.
It only takes three things to fire an engine:  Fuel/Air, Compression and Spark.
One of those is missing or weak.  Missing is easy to find, weak is a little harder.
The timing on these engines isn't very adjustable.  You can adjust the dwell with the point gap, but you should set it accurately, and the carb to timing adjustment and there is some give here. 
With the throttle at the start position the roller or mark on the adjustable armature plate should just be touching the idle arm pickup.  As the throttle is advanced this opens the throttle and advances the spark.  This is called synchronization.
Check compression it should be about 60 psi after four pulls.
Make sure your gas is good and with the choke on you see fuel at the carb throat.
Pull the plugs after trying to start.  They should be wet with fuel.  If not, squirt fuel in the carb and try again.  If it starts or pops and then dies out you have a bad bulb or fuel pump.
Steps to diagnose
1.  Compression check - equal between cylinders more important than reading.  Two 40PSIs better than a 30 and 60.
2.  You have to see wet plugs after a few pulls with choke on
3.  Don't quickly conclude the spark is OK - get a spark tester or make one
4.  Recheck all point gap and spark plug gaps
5.  Have a beer
Good luck, you're close!

[Freedumb]

Thank you I'll get out there and pull on it some more. When my arm gives out I'll have that beer.

[Craig Weis]

What kind of three horse power has two cylinders? My buddy on Wind Rover has a six horse power with two cylinders, and I one cylinder with five horse power on my C-P 19.

Anyway, as a two cycle, the piston is 'home and up' on the compression stroke. The magnet and pick-up for the magneto had best be one on top each other.

The madding thing is, it is usually the spark plug fouled, wet, carbon. and stinky since these engines run a nat's ass off blubbery rich just to function.

It's all in the details. Good Luck. Oh any two cycle needs to have plenty of compression...as said...the only difference between a new engine and a worn out engine is a half an ounce of babbitt....skip..

[Freedumb]

The prob ended up being that the No. 1 plug wasn't delivering the spark. I guess I'm going to have to jump in and replace what's under the flywheel. But no time soon. I've got an oar and three stout buds. We can do it...
Aaron

[mgoller]

Sometimes just a cleaning of the points and resetting will do the trick.  Look at the coil too.  If its blown it will be bloated and cracked usually.  Use a fine 1000 grit wet sandpaper (dry) folded in half the size of a finger nail file and push and pull til the points are clean and flat again.  Then clean with some clean white paper.  Reset to 0.020".

Another thing you can do is hook up a multimeter from ground to the spark plug lead and set on ohms/resistance scale.  This will read back through coil.  You should see anywhere from 4500 (old) to 7200 (new) ohms resistance.  This wont test the condenser but they are usually OK.
Its not that hard to get the flywheel off if you get a puller.

[B.Hart]

I recently repaired a old 5hp merc that had been sittig in storage for many years, and it had a very fine crack in it. I replaced the coil and it runs like a brand new one now. The plastic seems to break down over time due to moisture and heat. Good luck   BILL