Sooty plug
 

Ive got a Honda 4 stroke 2HP outboard, needs a service really, but
I want to fix a slight problem myself.

It starts ok, runs at slow speed ok, but misfires from half
throttle plus.

I guess this is fuel starvation , or wrong mixture or blocked
air filter ? The plug was covered in black soot. Can the air
filter be cleaned, and where on earth is it ? Such a small engine.
There's a small screw on the side of the carb, mixture ?


Any ideas please ? Any manuals/diagrams online ?


Howard.


howard.uk at virgin.net

Sooty plug
 

howard wrote:
Ive got a Honda 4 stroke 2HP outboard, needs a service really, but
I want to fix a slight problem myself.

It starts ok, runs at slow speed ok, but misfires from half
throttle plus.

I guess this is fuel starvation , or wrong mixture or blocked
air filter ? The plug was covered in black soot. Can the air
filter be cleaned, and where on earth is it ? Such a small engine.
There's a small screw on the side of the carb, mixture ?


Any ideas please ? Any manuals/diagrams online ?


Howard.


howard.uk at virgin.net




this link might help you out.

http://www.spark-plugs.co.uk/pages/t.../diagnosis.htm

Brian

Sooty plug
 

Brian wrote:

howard wrote:

Ive got a Honda 4 stroke 2HP outboard, needs a service really, but
I want to fix a slight problem myself.

It starts ok, runs at slow speed ok, but misfires from half
throttle plus.

I guess this is fuel starvation , or wrong mixture or blocked
air filter ? The plug was covered in black soot. Can the air
filter be cleaned, and where on earth is it ? Such a small engine.
There's a small screw on the side of the carb, mixture ?


Any ideas please ? Any manuals/diagrams online ?


This is possibly breakdown of a capacitor or condensor in the ignition
system : the voltage increases with speed from the magneto or generator,
and eventually the component fails. As they are often self-healing, all
that happens is the capacitor fails, the spark vanishes, and a part of
the capacitor vapourises, the short circuit then vanishes with the
engine firing properly until the next time the voltage reaches
breakdown as the RPM increases.

So you can get a sort of bang - putt - putt - putt- bang - putt effect
where the engine shakes around and tries to rotate around the shaft,
with the RPM varying periodically.


On my 2 stroke, the capacitor responsible is buried under the flywheel.



Howard.


howard.uk at virgin.net




this link might help you out.

http://www.spark-plugs.co.uk/pages/t.../diagnosis.htm

Brian

Sooty plug
 

"Mike James" wrote in message
...
Brian wrote:

howard wrote:

Ive got a Honda 4 stroke 2HP outboard, needs a service really, but
I want to fix a slight problem myself.

It starts ok, runs at slow speed ok, but misfires from half
throttle plus.

I guess this is fuel starvation , or wrong mixture or blocked
air filter ? The plug was covered in black soot. Can the air
filter be cleaned, and where on earth is it ? Such a small engine.
There's a small screw on the side of the carb, mixture ?


Any ideas please ? Any manuals/diagrams online ?


This is possibly breakdown of a capacitor or condensor in the ignition
system : the voltage increases with speed from the magneto or generator,
and eventually the component fails. As they are often self-healing, all
that happens is the capacitor fails, the spark vanishes, and a part of
the capacitor vapourises, the short circuit then vanishes with the
engine firing properly until the next time the voltage reaches
breakdown as the RPM increases.

So you can get a sort of bang - putt - putt - putt- bang - putt effect
where the engine shakes around and tries to rotate around the shaft,
with the RPM varying periodically.


On my 2 stroke, the capacitor responsible is buried under the flywheel.



Howard.


howard.uk at virgin.net




this link might help you out.

http://www.spark-plugs.co.uk/pages/t.../diagnosis.htm

Brian


Wow! That was good info.

Eisboch

Sooty plug
 

hiya
i doesnt sound like fuel starvation to me either, and a sooty plug is
not really relevent with unleaded as modern petrol is really sooty on a
correctly set up engine.
Just look at car tailpipes you never see grey deposits anymore just
jet black.

fragged

Sooty plug
 

billybob wrote:

hiya
i doesnt sound like fuel starvation to me either, and a sooty plug is
not really relevent with unleaded as modern petrol is really sooty on a
correctly set up engine.
Just look at car tailpipes you never see grey deposits anymore just jet
black.

fragged


Grey car exhausts was due to the lead - the current black is soot from
when they are cold, then nothing when they are warm. Plug colours
haven't changed - sooty plug is too rich, idled too much, too many cold
starts, oil leaking in... or one or two more things I've forgotten.

It sure ain't starvation!

Andy