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  1. R

    1990 Force 120HP #2 Cyl zero compression and upon opening piston shows damage

    Recheck your measurement at the bottom.----Piston might be out of round.-----When it left the factory it would have been 3.371 / 3.372?
  2. R

    Compression testing, hot or cold?

    You have a bad gauge or a motor that needs an overhaul.------You can do what you like , but I would remove bypass covers ( transfer covers ) and have a look at the pistons / rings.-----And before you ask there is no head gasket on that motor.
  3. R

    1990 Force 120HP #2 Cyl zero compression and upon opening piston shows damage

    They will be 3.365 or less at the rings ----They will be 3.368 / 3.367 at the bottom.-----Piston clearance is determined with the measurement at the bottom!
  4. R

    1972 Evinrude 50hp selectric

    See post #9-----I started working on outboards BEFORE your motor was made.-----But it is your motor to work on and learn as you go.
  5. R

    1972 Evinrude 50hp selectric

    Remove sparkplugs.-----Turn key on.-----Put control in forward.------Turn flywheel with socket and ratchet.----Should shift to neutral after about one turn.----Put control in reverse.-----Should be in reverse after about 2 turns.----Yes a good unit shift that easy !
  6. R

    Force 70 HP - Full throttle in reverse but underpowered in forward

    But the spark test does not involve the sparkplug.----It is a MAXIMUM OUTPUT test of the ignition system.----A good ignition can jump a gap of 3/8" or more!----Check the reed valves as well.
  7. R

    1972 Evinrude 50hp selectric

    Does the gearcase shift for you ?
  8. R

    1973 Mercury 115 2 stroke engine questions

    A number SAE 30 oil was used in those early units.-----Good enuff for a test.
  9. R

    1973 Mercury 115 2 stroke engine questions

    Some old time Mercury dealer might have a key, on hand.------Inspect wiring on motor and inside control box.-----Key switch might have a number on it.----Is there a knob under the pump reservoir ?---Do a spark check as well.---Do a compression test before spending any beer tokens.----If motor is...
  10. R

    Johnson 90 ELUA 1997 water pump

    How old was the old impeller ? ----Did vanes have a " set " on them and were they curved ?
  11. R

    Johnson 90 ELUA 1997 water pump

    Agreed it takes a lot more effort with a new impeller.----Did you use factory parts or something else ?
  12. R

    Lowest compression you’d buy

    Depends on how you want it to run !-----Had a 30 Johnson here a few years ago.------Showed owner the scored piston.-----Did not want it fixed.-----Had no idea how serious it was.-----Says his motor runs great.-----Most folks think that if a motor " can run " there cannot be anything wrong with it !!
  13. R

    1990 Force 120HP #2 Cyl zero compression and upon opening piston shows damage

    Measured a brand new piston for a Mercury.-----It has 0.008" taper.------If a piston is way too loose in the bore than crankcase compression can be lost right out the exhaust ports.-----Fitting new piston rings in old worn out grooves is a mistake as well.----This whole concept of a 2 stroke...
  14. R

    Force 70 HP - Full throttle in reverse but underpowered in forward

    Sounds like the motor is running on 2 of 3 cylinders.------Sounds great on a hose to the untrained ear.-----Will rev up running on 2 of 3 cylinders.-----Step #1 is compression test.---Post the numbers.-----Then check for strong spark on the 3 leads.----Must jump a gap of 5/16" or more.-----Revs...
  15. R

    1990 Force 120HP #2 Cyl zero compression and upon opening piston shows damage

    New piston might be 3.365 /3.367 " at the rings.-----3.372"at the skirt.-----Aluminum pistons expand at around 0.000012"/ inch / degree F ------New pistons are tapered and sized with clearance when cold.------When engines run clearances change.
  16. R

    40hp shearing flywheel keys?

    Do not use loctite on the tapers.----Often the hardware store key sticks out too much.----Then the flywheel cannot be pushed down on the tapers.----Remember , the key locates the flywheel for timing.----The locking tapers drive the flywheel.----The locking tapers eliminate any motion between...
  17. R

    How to take out rounded drain plug on force 85? Is there a way to drain without taking it out? Like pumping out the fluid maybe?

    I do not like those.----But use a pointy punch and hammer and you can get it to turn.
  18. R

    Yamaha 25hp outboard

    Hard to comprehend 4 1/2 hrs to clear a tell tale.-----Sounds like a tall tale to me.
  19. R

    1990 Force 120HP #2 Cyl zero compression and upon opening piston shows damage

    Well----In post #1 you state that you " have the tools and the know how " -----I believe you need to study some more ---Sorry.
  20. R

    1972 Evinrude 50hp selectric

    If I picked up a 1972 outboard motor for cheap ??----I would tear it down and do a complete evaluation before spending any beer tokens for parts.----First post the actual compression values here.-------Is your battery top notch / load tested?----Is the starter in top condition ??----Does the...
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