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