simpkinslarry
Cadet
- Joined
- Aug 1, 2007
- Messages
- 6
I own a 1973 Evinrude 65hp "Triumph" 3 cylinder that overall runs very
well. The motor is properly installed (correct height and trim
position) on a 15' deep-vee runabout/ski boat. I have a small problem
on initial throttle opening. When opening the throttle under load (in
gear on the boat)from idle there is always a misfire kind of burble
just before the revs start to pick up. It would appear that this
takes place just as the throttle butterflies pass the three
progression holes drilled in the carb throttle bore. After passing
through this misfire the engine revs up normally and runs very
smoothly. This problem is particularly annoying when trying to pull
out a beginning skier (I teach a lot of kids to water ski)as it means
there is a hesitation on the tow rope just as the boat starts moving
which often dumps the beginner skier. I have a official OMC manual for
the engine and I have overhauled the carbs, set up float levels, set
the throttle sync linkage and set the timing all per the manual. I
have installed a new water pump & thermostat and the engine is running
at the correct temperatures per the manual. I use the correct oil and
ratio(50:1)and use 97 gas. I have tried to set the idle exactly per
the manual(in gear on the water). I'm still not real happy with the
idle though it is rather rough and some times the motor dies when
moving from idle in gear. This happens usually when the engine has
been idling out of gear for a while and my technique is to rev the
engine in neutral first, let it slow down to the 1000rpm idle speed
and then put it in gear.(I still get the misfire/burble when opening
the throttle in gear though).
My questions are: Should I be setting the mixture differently to what
the OMC manual says? I start at the mixture screw 5/8 open and work
from there which seems to end up around 1 whole turn open on all carbs.
Should I set the timing differently than the OMC manual says? How
critical is the idle timing? Is it better to set it "by ear" rather
than rely on using a strobe?
Any ideas from all you OMC 3 cylinder "looper" enthusiasts out there?
Larry Simpkins
well. The motor is properly installed (correct height and trim
position) on a 15' deep-vee runabout/ski boat. I have a small problem
on initial throttle opening. When opening the throttle under load (in
gear on the boat)from idle there is always a misfire kind of burble
just before the revs start to pick up. It would appear that this
takes place just as the throttle butterflies pass the three
progression holes drilled in the carb throttle bore. After passing
through this misfire the engine revs up normally and runs very
smoothly. This problem is particularly annoying when trying to pull
out a beginning skier (I teach a lot of kids to water ski)as it means
there is a hesitation on the tow rope just as the boat starts moving
which often dumps the beginner skier. I have a official OMC manual for
the engine and I have overhauled the carbs, set up float levels, set
the throttle sync linkage and set the timing all per the manual. I
have installed a new water pump & thermostat and the engine is running
at the correct temperatures per the manual. I use the correct oil and
ratio(50:1)and use 97 gas. I have tried to set the idle exactly per
the manual(in gear on the water). I'm still not real happy with the
idle though it is rather rough and some times the motor dies when
moving from idle in gear. This happens usually when the engine has
been idling out of gear for a while and my technique is to rev the
engine in neutral first, let it slow down to the 1000rpm idle speed
and then put it in gear.(I still get the misfire/burble when opening
the throttle in gear though).
My questions are: Should I be setting the mixture differently to what
the OMC manual says? I start at the mixture screw 5/8 open and work
from there which seems to end up around 1 whole turn open on all carbs.
Should I set the timing differently than the OMC manual says? How
critical is the idle timing? Is it better to set it "by ear" rather
than rely on using a strobe?
Any ideas from all you OMC 3 cylinder "looper" enthusiasts out there?
Larry Simpkins
